Search

Background: Genome-wide association studies (GWAS) have revealed numerous loci for kidney function (estimated glomerular filtration rate, eGFR). The relationship of polygenic predictors of eGFR, risk of incident adverse kidney outcomes, and the plasma proteome is not known. Methods: We developed a genome-wide polygenic risk score (PRS) for eGFR by applying the LDpred algorithm to summary statistics generated from a multiethnic meta-analysis of CKDGen Consortium GWAS (N=765,348) and UK Biobank GWAS (90% of the cohort; N=451,508), followed by best parameter selection using the remaining 10% of UK Biobank (N=45,158). We then tested the association of the PRS in the Atherosclerosis Risk in Communities (ARIC) study (N=8,866) with incident chronic kidney disease, kidney failure, and acute kidney injury. We also examined associations between the PRS and 4,877 plasma proteins measured at at middle age and older adulthood and evaluated mediation of PRS associations by eGFR. Results: The developed PRS showed significant associations with all outcomes with hazard ratios (95% CI) per 1 SD lower PRS ranged from 1.06 (1.01, 1.11) to 1.33 (1.28, 1.37). The PRS was significantly associated with 132 proteins at both time points. The strongest associations were with cystatin-C, collagen alpha-1(XV) chain, and desmocollin-2. Most proteins were higher at lower kidney function, except for 5 proteins including testican-2. Most correlations of the genetic PRS with proteins were mediated by eGFR. Conclusions: A PRS for eGFR is now sufficiently strong to capture risk for a spectrum of incident kidney diseases and broadly influences the plasma proteome, primarily mediated by eGFR.

Many Mendelian randomization (MR) studies have recently been published, with inferences on the causal relationships between risk factors and diseases that have potential implications for clinical research. In nephrology, MR methods have been applied to investigate potential causal relationships of traditional risk factors, lifestyle factors, and biomarkers from omics technologies with kidney function or chronic kidney disease. This primer summarizes the basic concepts of MR studies, highlighting methods employed in recent applications, and emphasizes key elements in conducting and reporting of MR studies that are important for interpreting the results.

Background Polypharamacy is common among patients with chronic kidney disease (CKD), but little is known about urinary excretion of many drugs and their metabolites among CKD patients. Methods To evaluate self-reported medication use in relation to urine drug metabolite levels in a large cohort of CKD patients, the Germany Chronic Kidney Disease study, we ascertained self-reported use of 158 substances and 41 medication groups and coded active ingredients according to the Anatomical Therapeutic Chemical classification system. We used a nontargeted mass spectrometry-based approach to quantify metabolites in urine; calculated specificity, sensitivity, and accuracy of medication use and corresponding metabolite measurements; and used multivariable regression models to evaluate associations and prescription patterns. Results Among 4885 participants, there were 108 medication-drug metabolite pairs based on reported medication use and 78 drug metabolites. Accuracy was excellent for measurements of 36 individual substances in which the unchanged drug was measured in urine (median, 98.5%; range 61.1%-100%). For 66 pairs of substances and their related drug metabolites, median measurement-based specificity and sensitivity were 99.2% (range 84.0%-100%) and 71.7% (range 1.2%-100%), respectively. Commonly prescribed medications for hypertension and cardiovascular risk reduction-including angiotensin-II receptor blockers, calcium channel blockers, and metoprolol-showed high sensitivity and specificity. Although self-reported use of prescribed analgesics (acetaminophen, ibuprofen) was

The genome-wide association study (GWAS) is a powerful means to study genetic determinants of disease traits and generate insights into disease pathophysiology. To date, few GWAS of circulating metabolite levels have been performed in African Americans with chronic kidney disease. Hypothesizing that novel genetic-metabolite associations may be identified in a unique population of African Americans with a lower glomerular filtration rate (GFR), we conducted a GWAS of 652 serum metabolites in 619 participants (mean measured glomerular filtration rate 45 mL/min/1.73m(2)) in the African American Study of Kidney Disease and Hypertension, a clinical trial of blood pressure lowering and antihypertensive medication in African Americans with chronic kidney disease. We identified 42 significant variant metabolite associations. Twenty associations had been previously identified in published GWAS, and eleven novel associations were replicated in a separate cohort of 818 African Americans with genetic and metabolomic data from the Atherosclerosis Risk in Communities Study. The replicated novel variant-metabolite associations comprised eight metabolites and eleven distinct genomic loci. Nine of the replicated associations represented clear enzyme-metabolite interactions, with high expression in the kidneys as well as the liver. Three loci (ACY1, ACY3, and NAT8) were associated with a common pool of metabolites, acetylated amino acids, but with different individual affinities. Thus, extensive metabolite profiling in an African American population with chronic kidney disease aided identification of novel genome-wide metabolite associations, providing clues about substrate specificity and the key roles of enzymes in modulating systemic levels of metabolites.

BACKGROUND AND OBJECTIVES: Genetic variants in NAT8, a liver- and kidney-specific acetyltransferase encoding gene, have been associated with eGFR and CKD in European populations. Higher circulating levels of two NAT8-associated metabolites, N-δ-acetylornithine and N-acetyl-1-methylhistidine, have been linked to lower eGFR and higher risk of incident CKD in the Black population. We aimed to expand upon prior studies to investigate associations between rs13538, a missense variant in NAT8, N-acetylated amino acids, and kidney failure in multiple, well-characterized cohorts. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted analyses among participants with genetic and/or serum metabolomic data in the African American Study of Kidney Disease and Hypertension (AASK; n=962), the Atherosclerosis Risk in Communities (ARIC) study (n=1050), and BioMe, an electronic health record–linked biorepository (n=680). Separately, we evaluated associations between rs13538, urinary N-acetylated amino acids, and kidney failure in participants in the German CKD (GCKD) study (n=1624). RESULTS: Of 31 N-acetylated amino acids evaluated, the circulating and urinary levels of 14 were associated with rs13538 (P

Blood pressure and kidney function have a bidirectional relation. Hypertension has long been considered as a risk factor for kidney function decline. However, whether intensive blood pressure control could promote kidney health has been uncertain. The kidney is known to have a major role in affecting blood pressure through sodium extraction and regulating electrolyte balance. This bidirectional relation makes causal inference between these two traits difficult. Therefore, to examine the causal relations between these two traits, we performed two-sample Mendelian randomization analyses using summary statistics of large-scale genome-wide association studies. We selected genetic instruments more likely to be specific for kidney function using meta-analyses of complementary kidney function biomarkers (glomerular filtration rate estimated from serum creatinine [eGFRcr], and blood urea nitrogen from the CKDGen Consortium). Systolic and diastolic blood pressure summary statistics were from the International Consortium for Blood Pressure and UK Biobank. Significant evidence supported the causal effects of higher kidney function on lower blood pressure. Based on the mode-based Mendelian randomization method, the effect estimates for one standard deviation (SD) higher in log-transformed eGFRcr was -0.17 SD unit (95 % confidence interval: -0.09 to -0.24) in systolic blood pressure and -0.15 SD unit (95% confidence interval: -0.07 to -0.22) in diastolic blood pressure. In contrast, the causal effects of blood pressure on kidney function were not statistically significant. Thus, our results support causal effects of higher kidney function on lower blood pressure and suggest preventing kidney function decline can reduce the public health burden of hypertension.

Background Hypothyroidism and low free triiodothyronine (FT3) syndrome [low FT3 levels with normal thyroid-stimulating hormone (TSH)] have been associated with reduced kidney function cross-sectionally in chronic kidney disease (CKD) patients with severely reduced estimated glomerular filtration rate (eGFR) or end-stage kidney disease (ESKD). Results on the prospective effects of impaired thyroid function on renal events and mortality for patients with severely reduced eGFR or from population-based cohorts are conflicting. Here we evaluated the association between thyroid and kidney function with eGFR (cross-sectionally) as well as renal events and mortality (prospectively) in a large, prospective cohort of CKD patients with mild to moderately reduced kidney function. Methods Thyroid markers were measured among CKD patients from the German Chronic Kidney Disease study. Incident renal endpoints (combined ESKD, acute kidney injury and renal death) and all-cause mortality were abstracted from hospital records and death certificates. Time to first event analysis of complete data from baseline to the 4-year follow-up (median follow-up time 4.04 years) of 4600 patients was conducted. Multivariable linear regression and Cox proportional hazards models were fitted for single and combined continuous thyroid markers [TSH, free thyroxine (FT4), FT3] and thyroid status. Results Cross-sectionally, the presence of low-FT3 syndrome showed a significant inverse association with eGFR and continuous FT3 levels alone showed a significant positive association with eGFR; in combination with FT4 and TSH, FT3 levels also showed a positive association and FT4 levels showed a negative association with eGFR. Prospectively, higher FT4 and lower FT3 levels were significantly associated with a higher risk of all-cause mortality (Nevents = 297). Per picomole per litre higher FT3 levels the risk of reaching the composite renal endpoint was 0.73-fold lower (95% confidence interval 0.65–0.82; Nevents = 615). Compared with euthyroid patients, patients with low-FT3 syndrome had a 2.2-fold higher risk and patients with hypothyroidism had a 1.6-fold higher risk of experiencing the composite renal endpoint. Conclusions Patients with mild to moderate CKD suffering from thyroid function abnormalities are at an increased risk of adverse renal events and all-cause mortality over time.

The past few years have seen major advances in genome-wide association studies (GWAS) of CKD and kidney function–related traits in several areas: increases in sample size from >100,000 to >1 million, enabling the discovery of >250 associated genetic loci that are highly reproducible; the inclusion of participants not only of European but also of non-European ancestries; and the use of advanced computational methods to integrate additional genomic and other unbiased, high-dimensional data to characterize the underlying genetic architecture and prioritize potentially causal genes and variants. Together with other large-scale biobank and genetic association studies of complex traits, these GWAS of kidney function–related traits have also provided novel insight into the relationship of kidney function to other diseases with respect to their genetic associations, genetic correlation, and directional relationships. A number of studies also included functional experiments using model organisms or cell lines to validate prioritized potentially causal genes and/or variants. In this review article, we will summarize these recent GWAS of CKD and kidney function–related traits, explain approaches for downstream characterization of associated genetic loci and the value of such computational follow-up analyses, and discuss related challenges along with potential solutions to ultimately enable improved treatment and prevention of kidney diseases through genetics.

Funder: Government Department of Business, Funder: Energy and Industrial Strategy (BEIS), Funder: Vice-Chancellor Fellowship from the University of Bristol, Funder: Shanghai Thousand Talents Program, Funder: Academy of Medical Sciences (AMS) Springboard Award, Funder: BBSRC Innovation fellowship, Funder: NIHR Biomedical Research Centre at University Hospitals Bristol NHS Foundation Trust and the University of Bristol, BACKGROUND: This study was to systematically test whether previously reported risk factors for chronic kidney disease (CKD) are causally related to CKD in European and East Asian ancestries using Mendelian randomization. METHODS: A total of 45 risk factors with genetic data in European ancestry and 17 risk factors in East Asian participants were identified as exposures from PubMed. We defined the CKD by clinical diagnosis or by estimated glomerular filtration rate of 25 kg/m2. CONCLUSIONS: Eight cardiometabolic risk factors showed causal effects on CKD in Europeans and three of them showed causality in East Asians, providing insights into the design of future interventions to reduce the burden of CKD.

Simple Summary Clear cell renal cell carcinoma is a common malignancy that represents 80% of all kidney tumors. Most tumors harbor an inactivation of the VHL gene, leading to the accumulation of HIF-1α and HIF-2α. Promising clinical results of specific HIF-2α inhibitors will soon lead to new treatment options for advanced cancer patients, although primary and acquired resistance to these agents are common. We here show that Acriflavine, which inhibits both HIF-1α and HIF-2α, and Fingolimod (FTY720), which inhibits sphingosine-1-phosphate signaling, show therapeutic activities in several experimental ccRCC models that are resistant to HIF-2α-inhibitor treatment. Additionally, we show that specific HIF-2α-inhibition suppresses the tumor immune microenvironment, which will be important to consider for future combination studies with immune checkpoint inhibitors. Abstract Specific inhibitors of HIF-2α have recently been approved for the treatment of ccRCC in VHL disease patients and have shown encouraging results in clinical trials for metastatic sporadic ccRCC. However, not all patients respond to therapy and pre-clinical and clinical studies indicate that intrinsic as well as acquired resistance mechanisms to HIF-2α inhibitors are likely to represent upcoming clinical challenges. It would be desirable to have additional therapeutic options for the treatment of HIF-2α inhibitor resistant ccRCCs. Here we investigated the effects on tumor growth and on the tumor microenvironment of three different direct and indirect HIF-α inhibitors, namely the HIF-2α-specific inhibitor PT2399, the dual HIF-1α/HIF-2α inhibitor Acriflavine, and the S1P signaling pathway inhibitor FTY720, in the autochthonous Vhl/Trp53/Rb1 mutant ccRCC mouse model and validated these findings in human ccRCC cell culture models. We show that FTY720 and Acriflavine exhibit therapeutic activity in several different settings of HIF-2α inhibitor resistance. We also identify that HIF-2α inhibition strongly suppresses T cell activation in ccRCC. These findings suggest prioritization of sphingosine pathway inhibitors for clinical testing in ccRCC patients and also suggest that HIF-2α inhibitors may inhibit anti-tumor immunity and might therefore be contraindicated for combination therapies with immune checkpoint inhibitors.

Background GSTM1 encodes glutathione S-transferase μ-1 (GSTM1), which belongs to a superfamily of phase 2 antioxidant enzymes. The highly prevalent GSTM1 deletion variant is associated with kidney disease progression in human cohorts: the African American Study of Kidney Disease and Hypertension and the Atherosclerosis Risk in Communities (ARIC) Study. Methods We generated a Gstm1 knockout mouse line to study its role in a CKD model (involving subtotal nephrectomy) and a hypertension model (induced by angiotensin II). We examined the effect of intake of cruciferous vegetables and GSTM1 genotypes on kidney disease in mice as well as in human ARIC study participants. We also examined the importance of superoxide in the mediating pathways and of hematopoietic GSTM1 on renal inflammation. Results Gstm1 knockout mice displayed increased oxidative stress, kidney injury, and inflammation in both models. The central mechanism for kidney injury is likely mediated by oxidative stress, because treatment with Tempol, an superoxide dismutase mimetic, rescued kidney injury in knockout mice without lowering BP. Bone marrow crosstransplantation revealed that Gstm1 deletion in the parenchyma, and not in bone marrow-derived cells, drives renal inflammation. Furthermore, supplementation with cruciferous broccoli powder rich in the precursor to antioxidant-activating sulforaphane significantly ameliorated kidney injury in Gstm1 knockout, but not wild-type mice. Similarly, among humans (ARIC study participants), high consumption of cruciferous vegetables was associated with fewer kidney failure events compared with low consumption, but this association was observed primarily in participants homozygous for the GSTM1 deletion variant. Conclusions Our data support a role for the GSTM1 enzyme in the modulation of oxidative stress, inflammation, and protective metabolites in CKD.

Prevalence estimates and evidence informing treatment targets for thyroid dysfunction largely come from studies of middle-aged adults. We conducted a cross-sectional analysis to determine the prevalence of thyroid dysfunction and risk factors for abnormal thyroid tests in participants aged ≥65 in the Atherosclerosis Risk in Communities (ARIC) study (N = 5,392). We measured serum concentrations of triiodothyronine (T3), free thyroxine (FT4), thyroid peroxidase antibody (Anti-TPO), and thyroid stimulating hormone (TSH). In this population (58% women, 22% black), 17% reported medication use for thyroid dysfunction. Among those not on treatment, the prevalence of overt and subclinical hypothyroidism was 0.82% and 6.06%, respectively. Overt and subclinical hyperthyroidism affected 0.26% and 0.78%, respectively. Multivariable adjusted TSH, FT4 and T3 levels were 25%, 1.3% and 3.9% lower in blacks compared to whites, respectively. Men were less likely to be anti-TPO positive compared to women (p

Clinical kidney journal : CKJ 12(5), 663-672 (2019). doi:10.1093/ckj/sfz046, Published by Oxford Univ. Press, Oxford

Background and Aims Chronic kidney disease (CKD) affects >10% of the adult population worldwide and is associated with increased risk of kidney failure (KF) and mortality. Mechanisms underlying the variable course of disease progression are incompletely understood. This study aimed at identifying novel metabolite biomarkers of adverse kidney outcomes and overall mortality, which may offer insights into pathophysiological mechanisms. Method Using measurements of 1,487 metabolites in urine of 5,087 CKD patients enrolled in the German Chronic Kidney Disease study, we evaluated the association of urine metabolite levels with adverse events. Main endpoints include KF, a combined endpoint of KF and acute kidney injury (KF+AKI), and overall mortality. Statistical analysis was based on a discovery-replication design (ratio 2:1) and multivariable adjusted Cox regression models. We performed cause-specific hazard regression as well as subdistribution hazard analyses with death of other causes as a competing event for the endpoints KF and KF+AKI. Statistical significance was defined using a Bonferroni correction for the number of tested metabolites per stage. An association was considered replicated if effect estimates from both stages were significant and direction-consistent. Results Median follow-up time was 4 years. At time of analysis, 362 patients died, 241 experienced KF, and 382 KF+AKI. Overall, we identified 55 urine metabolites whose levels were significantly and reproducibly associated with adverse kidney outcomes and/or mortality. Cause-specific and subdistribution hazard analyses showed almost identical results. Higher levels of the amino acid C-glycosyltryptophan in urine were associated with higher risk for all three endpoints (KF: hazard ratio 1.43, 95% confidence interval [1.27;1.61], KF+AKI: 1.40 [1.27;1.55], mortality: 1.47 [1.33;1.63]). The cumulative incidence function of KF was higher for each quartile of urine C-glycosyltryptophan levels and the effect were most pronounced in the highest quartile (see Figure). The replicated metabolites belong to different biochemical classes, and those belonging to the phosphatidylcholines pathway showed enrichment. Members of this pathway contributed to the improvement of the prediction performance for KF observed when multiple metabolites were added to the well-established kidney failure risk equation by Tangri. Conclusion This comprehensive screen of the association between urine metabolite levels and adverse kidney outcomes and mortality identified and replicated 55 urine metabolites associated with adverse kidney events, potentially providing new insights into the mechanisms of kidney disease progression. The study represents a valuable resource for future experimental studies of biomarkers of CKD progression.

Background and Aims Osteopontin (OPN) is synthesized in the thick ascending limb of Henle’s loop and in the distal tubule. Numerous studies have shown that OPN mRNA and protein expression is increased in animal models of many different renal diseases, especially glomerular diseases as well as diabetic nephropathy. Here, high OPN expression correlated with proteinuria, reduction of creatinine clearance, fibrosis as well as macrophage and T-cell infiltration. OPN has therefore been suggested to be a promising biomarker for various kidney diseases. Further studies are needed to fully understand its role in kidney (patho-)physiology and its potential as a marker of kidney disease progression and adverse renal events. We therefore evaluated the association of OPN with kidney events and all-cause mortality in a cohort of CKD patients, the German Chronic Kidney Disease (GCKD) study. Method OPN was measured from baseline serum samples using the Quantikine Human OPN Immunoassay. Coefficients of variation were Results Over 6.5 years of follow-up, 473 kidney events and 582 deaths occurred among 4,950 GCKD patients. Hundred-and-forty-eight deaths and 62 kidney events occurred in 1,143 hypertensive nephropathy patients, 49 deaths and 118 kidney events occurred in 935 primary glomerular nephropathy patients, and 170 deaths and 99 kidney events in diabetic nephropathy patients (Table 1). Overall mean age was 60.1 years (±12.0), with 60.3% men. Median OPN levels were 29.2 ng/mL (IQR 21.2). Cross-sectionally a 10% change in OPN was associated with 0.5% lower eGFR on average (p Conclusion Higher OPN levels were associated with lower eGFR and higher UACR cross-sectionally and significantly associated with a higher risk of renal events and all-cause mortality especially for diabetic nephropathy patients even after adjustment for baseline eGFR, UACR and other confounding factors. These results are supportive of OPN being a potential marker of CKD progression and mortality.

Background and Aims Chronic kidney disease (CKD) patients are prone to prescription of multiple medications. Medication adherence is a well-recognized problem in the management of patients with chronic diseases requiring polypharmacy. This study aimed to evaluate the connection between self-reported medication use and urine drug metabolite levels in a large cohort of CKD patients, the GCKD study, as a basis for future pharmacometabolomics studies. Method Self-reported medication use of 160 substances and 41 medication groups was ascertained at study baseline and coded according to the Anatomical Therapeutic Chemical classification system. A non-targeted mass spectrometry-based approach (Metabolon HD4™) was used for concomitant metabolite quantification in urine. Specificity, sensitivity and accuracy of medication use and the corresponding urine metabolite measurements were calculated. Multivariable regression models (adjusted to age, sex, eGFR, log(UACR), systolic blood pressure, LDL, log(triglycerides), log(HBA1c) were used to establish associations in prescription patterns. Results Among 4,885 participants, 78 drug metabolites were detected in urine (frequency range: 0.4-58%) and assigned into 110 medication – drug metabolite pairs (MMPs) based on reported individual substances and medication groups. For all 68 MMPs of individual substances, accuracy of medication use and the corresponding drug metabolite measurement was excellent (median 97.0%, range 43%-100%), as was measurement-based specificity (median 99.3%, range 73.3%-100%; Fig. 1). Median measurement-based sensitivity was 72.1% (range 1.1%-100%, Fig. 1). Sensitivity and specificity were especially high for angiotensin-II receptor blockers (92%-96%; 99-100%), calcium channel blockers (85-100%; 91-100%), and metoprolol (90%; 98% respectively) commonly prescribed and important medications for blood pressure control and cardiovascular risk reduction in CKD patients. MMPs showing sensitivity Conclusion This study provides a comprehensive screen of the associations between urine drug metabolite levels and self-reported medication use. It supports the usefulness of pharmacometabolomics to assess medication use, frequency of OTC analgesics use, and prescription patterns in persons with CKD.

IMPORTANCE Early identification of individuals at elevated risk of developing chronic kidney disease (CKD) could improve clinical care through enhanced surveillance and better management of underlying health conditions.OBJECTIVE To develop assessment tools to identify individuals at increased risk of CKD, defined by reduced estimated glomerular filtration rate (eGFR).DESIGN, SETTING, AND PARTICIPANTS Individual-level data analysis of 34 multinational cohorts from the CKD Prognosis Consortium including 5 222 711 individuals from 28 countries. Data were collected from April 1970 through January 2017. A 2-stage analysis was performed, with each study first analyzed individually and summarized overall using a weighted average. Because clinical variables were often differentially available by diabetes status, models were developed separately for participants with diabetes and without diabetes. Discrimination and calibration were also tested in 9 external cohorts (n = 2 253 540).EXPOSURES Demographic and clinical factors.MAIN OUTCOMES AND MEASURES Incident eGFR of less than 60 mL/min/1.73 m(2).RESULTS Among 4 441 084 participants without diabetes (mean age, 54 years, 38% women), 660 856 incident cases (14.9%) of reduced eGFR occurred during a mean follow-up of 4.2 years. Of 781 627 participants with diabetes (mean age, 62 years, 13% women), 313 646 incident cases (40%) occurred during a mean follow-up of 3.9 years. Equations for the 5-year risk of reduced eGFR included age, sex, race/ethnicity, eGFR, history of cardiovascular disease, ever smoker, hypertension, body mass index, and albuminuria concentration. For participants with diabetes, the models also included diabetes medications, hemoglobin A(1c), and the interaction between the 2. The risk equations had a median C statistic for the 5-year predicted probability of 0.845 (interquartile range [IQR], 0.789-0.890) in the cohorts without diabetes and 0.801 (IQR, 0.750-0.819) in the cohorts with diabetes. Calibration analysis showed that 9 of 13 study populations (69%) had a slope of observed to predicted risk between 0.80 and 1.25. Discrimination was similar in 18 study populations in 9 external validation cohorts; calibration showed that 16 of 18 (89%) had a slope of observed to predicted risk between 0.80 and 1.25.CONCLUSIONS AND RELEVANCE Equations for predicting risk of incident chronic kidney disease developed from more than 5 million individuals from 34 multinational cohorts demonstrated high discrimination and variable calibration in diverse populations. Further study is needed to determine whether use of these equations to identify individuals at risk of developing chronic kidney disease will improve clinical care and patient outcomes.

Vogt, Bruno/0000-0002-1548-6387; Dufek, Stephanie/0000-0002-6323-6673; Liu, Lili/0000-0002-2622-9669; Paczek, Leszek/0000-0003-0160-3009; Cui, Zhao/0000-0002-5837-1926; amoroso, antonio/0000-0002-9437-9407; Rosen, Raphael/0000-0003-1025-1965; Loos, Ruth/0000-0002-8532-5087; coenen, marieke/0000-0001-8796-2031; zanoni, francesca/0000-0001-9567-6713; CUCCA, Francesco/0000-0002-7414-1995; Ars, Elisabet/0000-0002-4118-4358; Hamilton, Patrick/0000-0001-6703-3745 WOS:000563559600001 PubMed ID: 32231244 Membranous Nephropathy (MN) is a rare autoimmune cause of kidney failure. Here we report a genome-wide association study (GWAS) for primary MN in 3,782 cases and 9,038 controls of East Asian and European ancestries. We discover two previously unreported loci, NFKB1 (rs230540, OR = 1.25, P = 3.4 x 10(-12)) and IRF4 (rs9405192, OR = 1.29, P = 1.4 x 10(-14)), fine-map the PLA2R1 locus (rs17831251, OR = 2.25, P = 4.7 x 10(-103)) and report ancestry-specific effects of three classical HLA alleles: DRB1*1501 in East Asians (OR = 3.81, P = 2.0 x 10(-49)), DQA1*0501 in Europeans (OR = 2.88, P = 5.7 x 10(-93)), and DRB1*0301 in both ethnicities (OR = 3.50, P = 9.2 x 10(-23) and OR = 3.39, P = 5.2 x 10(-82), respectively). GWAS loci explain 32% of disease risk in East Asians and 25% in Europeans, and correctly re-classify 20-37% of the cases in validation cohorts that are antibody-negative by the serum anti-PLA2R ELISA diagnostic test. Our findings highlight an unusual genetic architecture of MN, with four loci and their interactions accounting for nearly one-third of the disease risk. National Institute for Diabetes and Digestive Kidney Diseases (NIDDK) [RC2-DK116690, R01-DK105124, R01-DK097053, R01-DK108805]; National Institute on Minority Health and Health Disparities (NIMHD)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute on Minority Health & Health Disparities (NIMHD) [R01-MD009223]; Charles Woodson Clinical Research Fund; Nephrotic Syndrome Study Network Consortium (NEPTUNE) [U54-DK-083912]; Columbia University, Columbia Glomerular Center; Office of Rare Diseases Research, National Center for Advancing Translational Sciences (NCATS); National Institute of Diabetes, Digestive, and Kidney Diseases (NIDDK)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK); University of MichiganUniversity of Michigan System; NephCure Kidney International; Halpin Foundation; National Key Research and Development Program of China [2016YFC0904100]; Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [81621092]; National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [81870460, 81570598]; Science and Technology Innovation Action Plan of Shanghai Science and Technology Committee [17441902200]; Shanghai Municipal Education Commission, Gaofeng, Clinical Medicine Grant [20152207]; Shanghai Jiao Tong University School of Medicine, Multi-Center Clinical Research Project [DLY201510]; International Cooperation and Exchange Projects of Shanghai Science and Technology Committee [14430721000]; Outstanding Young Scholar Award [81622009]; Shanghai Health and Family Planning Committee Hundred Talents Program [2018BR37]; Seoul National University Hospital Human Biobank, a member of the National Biobank of Korea - Ministry of Health and Welfare, Republic of Korea; MRCMedical Research Council UK (MRC) [MR/J010847/1]; Manchester Academic Health Science Centre [MAHSC 186/200]; Greater Manchester Local Clinical Research Network; Kidneys for Life Charity; David and Elaine Potter Charitable Foundation; St Peter's Trust for Kidney, Bladder and Prostate Research; Kids Kidney Research UKKidney Research UK (KRUK); Kidney Research UKKidney Research UK (KRUK); Italian Ministry of Health grantMinistry of Health, Italy [GR-2011-02350438]; Department of Excellence Grant 2018-2022 - Italian Ministry of Education for the Department of Medical Sciences of the University of Turin; Columbia University; Poznan University of Medical Sciences, Poland; German Ministry of Education and Research (BMBF)Federal Ministry of Education & Research (BMBF) [01ER0804]; KfH Foundation for Preventive Medicine; Bayer Pharma AG; German Research FoundationGerman Research Foundation (DFG) [CRC 1140, KO 3598/3-1, CRC 992]; European Research CouncilEuropean Research Council (ERC) [ERC-2012ADG_2012-0314, 322947]; 7th Framework Programme of the European Community contract [2012-305608]; National Research Agency grant MNaims [ANR-17-CE17-0012-01]; Dutch Kidney Foundation [OW08, KJPB11.021]; National Human Genome Research Institute (NHGRI)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Human Genome Research Institute (NHGRI); NIMHD We are grateful to all study participants across multiple nephrology centres worldwide for their contributions to this work. This work was supported by the following institutions, grants and funding agencies in the US: Columbia University, Columbia Glomerular Center, National Institute for Diabetes and Digestive Kidney Diseases (NIDDK) grants RC2-DK116690 (K.K., M.K.), R01-DK105124 (K.K.), R01-DK097053 (L.H.B., M.K.), R01-DK108805 (M.G.S.), and National Institute on Minority Health and Health Disparities (NIMHD) grant R01-MD009223 (K.K., A.G.G., A.B.). M.G.S. is additionally supported by the Charles Woodson Clinical Research Fund. The Nephrotic Syndrome Study Network Consortium (NEPTUNE), U54-DK-083912, is a part of the National Institutes of Health (NIH) Rare Disease Clinical Research Network (RDCRN), supported through a collaboration between the Office of Rare Diseases Research, National Center for Advancing Translational Sciences (NCATS) and the National Institute of Diabetes, Digestive, and Kidney Diseases (NIDDK). Additional funding and/or programmatic support for this project has also been provided by the University of Michigan, the NephCure Kidney International and the Halpin Foundation. The recruitment and analysis of the Chinese cohorts were supported by the National Key Research and Development Program of China (2016YFC0904100), Natural Science Foundation of China to the Innovation Research Group (81621092), National Natural Science Foundation of China (No. 81870460, 81570598), Science and Technology Innovation Action Plan of Shanghai Science and Technology Committee (No.17441902200), Shanghai Municipal Education Commission, Gaofeng, Clinical Medicine Grant (No.20152207), Shanghai Jiao Tong University School of Medicine, Multi-Center Clinical Research Project (No.DLY201510), International Cooperation and Exchange Projects of Shanghai Science and Technology Committee (No.14430721000), the Outstanding Young Scholar Award for Zhao Cui (No.81622009), and Shanghai Health and Family Planning Committee Hundred Talents Program for Jingyuan Xie (No.2018BR37). The recruitment of the Korean cohort was supported by the Seoul National University Hospital Human Biobank, a member of the National Biobank of Korea, financed by the Ministry of Health and Welfare, Republic of Korea. P.B. and P.H. acknowledge financial support from MRC project "Autoimmunity in Membranous Nephropathy", grant MR/J010847/1 which funded the sample collection from MN patients across the UK. P.B., P.H. and S.H. acknowledge support from Manchester Academic Health Science Centre (MAHSC 186/200), the Greater Manchester Local Clinical Research Network and Kidneys for Life Charity for supporting research in MN in Manchester. We are grateful to the MENTOR study (clinical trials no. NCT01180036), for contributing blood samples of trial participants. The UK cohort was supported in part by grants from the David and Elaine Potter Charitable Foundation (to S.H.P. and R.K.), St Peter's Trust for Kidney, Bladder and Prostate Research (to D.B., H.C.S., S.H.P. and R.K.), Kids Kidney Research UK and Kidney Research UK (to D.B. and R.K.). The Italian cohorts were supported by the Italian Ministry of Health grant GR-2011-02350438 (G.Z., S.G.) and the Department of Excellence Grant 2018-2022 funded by the Italian Ministry of Education for the Department of Medical Sciences of the University of Turin (A.A.).; The recruitment of Polish cases was sponsored by the Polish Kidney Genetics Network (POLYGENES), a collaborative effort between Columbia University and Poznan University of Medical Sciences, Poland. The full list of POLYGENES collaborators can be found in the Supplementary Materials. The GCKD (German Chronic Kidney Disease) study was funded by grants from the German Ministry of Education and Research (BMBF, No. 01ER0804) and the KfH Foundation for Preventive Medicine, with genotyping supported by Bayer Pharma AG. The list of GCKD investigators can be found in the Supplementary Materials. The work of M.W. and A.K. was funded by the CRC 1140 Initiative and by KO 3598/3-1 and CRC 992 (A.K.) of the German Research Foundation. The work of E.H. and R.A.K.S. was funded by the CRC 1192 from the German Research Foundation (Projects B1 and C1). P.R. is a recipient of European Research Council ERC-2012ADG_2012-0314 grant 322947, 7th Framework Programme of the European Community contract 2012-305608 (European Consortium for High-Throughput Research in Rare Kidney Diseases), and the National Research Agency grant MNaims (ANR-17-CE17-0012-01). The Dutch studies were supported by grants from the Dutch Kidney Foundation to JMH and JFW (Nierstichting Nederland grant OW08 and grant KJPB11.021). We would like to thank the Population Architecture Using Genomics and Epidemiology (PAGE) consortium, funded by the National Human Genome Research Institute (NHGRI) with co-funding from the NIMHD, for providing population controls for this study. For full acknowledgment of the PAGE consortium, please see Supplementary Materials. The funding sources were not involved in the study design, collection, analysis, and interpretation of data, writing of the report, or in the decision to submit the paper for publication.

Background/Introduction Abnormal thyroid hormone concentrations have been associated with adverse cardiovascular outcomes, but the relationship between thyroid dysfunction and specific heart failure phenotypes is less clear. Purpose To examine the association of thyroid dysfunction with the risk of incident HF in older adults without pre-existing HF. Methods We analyzed participants enrolled in the Atherosclerosis Risk in Communities (ARIC) study who attended the visit 5 examination (2011–2013). Participants with previous HF history, and participants treated with amiodarone, levothyroxine, and antithyroid medication were excluded. We used Cox regression models to assess the associations between serum thyroid indices (free thyroxine [FT4], total triiodothyronine [TT3], or thyroid stimulating hormone [TSH]) and incident adjudicated HF with reduced (HFrEF) and preserved (HFpEF) left ventricular ejection fraction. Continuous associations between TT3 and outcome were further assessed via Cox model using restricted cubic spline. Results Among 3349 participants (mean age 75±5 years, 56% women, 20% black), subclinical hypothyroidism was prevalent in 12% of participants and low T3 syndrome in 3%. Those with overt hypothyroidism ( Conclusions In a contemporary biracial cohort of older adults, serum T3 level was inversely associated with incident HFpEF hospitalization. T3 administration could be considered as a potential target in future clinical trials preventing HFpEF hospitalization. Figure 1 Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): The Atherosclerosis Risk in Communities Study is performed as a collaborative study supported by National Heart, Lung, and Blood Institute contracts

Genome-wide association studies (GWAS) have revealed numerous loci for kidney function (estimated glomerular filtration rate, eGFR). The relationship of polygenic predictors of eGFR, risk of incident adverse kidney outcomes, and the plasma proteome is not known. We developed a genome-wide polygenic risk score (PRS) using a weighted average of 1.2 million SNPs for eGFR using the LDpred algorithm, summary statistics generated by a European-ancestry (EA) meta-analysis of the CKDGen Consortium (N=558,423) and UK Biobank GWAS for eGFR (90% of the cohort; N=289,432), followed by best parameter selection using data from the remaining 10% of the UK Biobank (N=32,159). We then tested the association of the PRS among 8,886 EA participants in the Atherosclerosis Risk in Communities (ARIC) study (mean age: 54±6 years, 53% female) with incident chronic kidney disease (CKD), end stage kidney disease (ESKD), kidney failure (KF), and acute kidney injury (AKI). We also examined 4,877 plasma proteins measured at two time points (visit 3 (1993-95) and visit 5 (2011-13)) in relation to the PRS and compared associations between the proteome and eGFR itself. All models were adjusted for age, sex, center, and the first 10 principal components of ancestry. The developed PRS had an R2for eGFR of 0.07 in ARIC. Over 30 years of follow up, the number of incident CKD, ESKD, KF, and AKI were 2,959, 137, 470, and 1,723, respectively. The PRS showed significant associations with all outcomes: hazard ratios (95% CI) per 1 SD lower PRS were 1.33 (1.28, 1.39), 1.20 (1.00, 1.42), 1.17 (1.06, 1.28), and 1.07 (1.02, 1.12) for incident CKD, ESKD, KF, and AKI respectively. The PRS was significantly associated (Bonferroni threshold P−5) with 108 proteins at both time points. The strongest associations were with cystatin-C (a marker of kidney function used in clinical practice), collagen alpha-1 (XV) chain, and desmocollin-2. All significant correlations with the PRS were negative, except those of testican-2 and angiostatin. Correlations of proteins with eGFR were much stronger than those with the PRS. Overall, we demonstrated that the PRS for eGFR is now sufficiently strong to capture risk for a spectrum of incident kidney diseases as well as broadly influence the plasma proteome.

BACKGROUNDThe chronic kidney disease (CKD) public health burden is substantial and has not declined as expected with current interventions on disease treatments. A large number of clinical, biological, and behavioural risk factors have been associated with CKD. However, it is unclear which of them are causal.OBJECTIVETo systematically test whether previously reported risk factors for CKD are causally related to the disease in European and East Asian ancestries.DESIGNTwo-sample Mendelian randomization (MR) and non-linear MR analyses.PARTICIPANTS53,703 CKD cases and 960,624 controls of European ancestry from CKDGen, UK Biobank and HUNT, and 13,480 CKD cases and 238,118 controls of East Asian ancestry from Biobank Japan, China Kadoorie Biobank and Japan-Kidney-Biobank/ToMMo.MEASURESSystematic literature mining of PubMed studies identified 45 clinical risk factors and biomarkers with robustly associated genetic variants, including phenotypes related to blood pressure, diabetes, glucose, insulin, lipids, obesity, smoking, sleep disorders, nephrolithiasis, uric acid, coronary artery disease, bone mineral density, homocysteine, C-reactive protein, micro-nutrients and thyroid function, which were selected as exposures. The outcome was CKD (defined by clinical diagnosis or by estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73m2).RESULTSEight risk factors showed evidence of causal effects on CKD in European ancestry, including body mass index (BMI), hypertension, systolic blood pressure, high density lipoprotein cholesterol, apolipoprotein A-I, lipoprotein A, type 2 diabetes (T2D) and nephrolithiasis. In East Asian ancestry, BMI, T2D and nephrolithiasis showed evidence of causal effects on CKD. Hypertension showed reliable evidence of a strong causal effect on CKD in Europeans but in contrast appeared to show a null effect in East Asians, suggesting the possibility of different causal risk factors in Europeans and East Asians. Although liability to T2D showed consistent effects on CKD, the effect of glycemic traits on CKD was weak, suggesting T2D may have glucose-independent mechanisms to influence CKD. Nonlinear MR indicated a threshold relationship between genetically predicted BMI and CKD, with increased risk at BMI above 25 kg/m2.LIMITATIONDue to the unbalanced distribution of data between ancestries, we could only test 17 of the 45 risk factors in East Asian participants.CONCLUSIONSEight CKD-associated risk factors showed evidence of causal effects on the disease in over 1.2 million European and East Asian ancestries. These risk factors were predominantly related to cardio-metabolic health, which supports the shared causal link between cardio-metabolic health and kidney function. This study provides evidence of potential intervention targets for primary prevention of CKD, which could help reduce the global burden of CKD and its cardio-metabolic co-morbidities.Research in contextEvidence before this studyChronic kidney disease (CKD) has a major effect on global health, both as a direct cause of morbidity and mortality, and as an important complication for cardio-metabolic diseases. However, even with the existing interventions, the burden of CKD has not declined as expected over the last 30 years. Existing epidemiological studies of CKD have mainly focused on disease treatment in patients from specific populations and estimated association rather than causality. A systematic assessment of the causal determinants of CKD in different populations is urgently needed, to help promote a shift from treatment of CKD patients to prevention of the disease in high-risk groups. The use of genetic data and the latest Mendelian randomization (MR) methodologies offers a cost-effective way to evaluate the potential intervention targets for prevention of CKD in high-risk groups.Added value of this studyIn this study, we systematically constructed a causal atlas of 45 risk factors on CKD in European and East Asian ancestries using MR. To maximise power of these analyses and accuracy of the findings, we collected and harmonised CKD genetic association data from six large-scale biobanks (in over 1.1 million Europeans and 250,000 East Asians). By applying a comprehensive MR framework, including linear two-sample MR, bidirectional MR, multivariable MR and non-linear MR approaches, we identified eight risk factors with reliable evidence of causal effects on CKD in European ancestry studies, including body mass index (BMI), hypertension, systolic blood pressure, high density lipoprotein cholesterol, apolipoprotein A-I, lipoprotein A, type 2 diabetes (T2D) and nephrolithiasis. In East Asian studies, BMI, T2D and nephrolithiasis also showed causal effects on CKD. Among other factors, hypertension showed reliable evidence of a strong causal effect on CKD in Europeans but in contrast appeared to show a null effect in East Asians. This MR finding together with previous literature evidence opens up the possibility that hypertension could play different causal roles on CKD across ancestries. For diabetes and glycemic phenotypes, our MR and sensitivity analyses suggested the causal role of liability of T2D on CKD but suggested weak effects of glycemic phenotypes on CKD. This aligns with the recent trial of SGLT2 inhibitors on kidney disease, which implies T2D may have glucose-independent mechanisms to influence CKD. For lipids phenotypes, we found good evidence to support the role of high-density lipoprotein cholesterol on CKD and further suggested the effects of two lipids targets: circulating CETP level and lipoprotein A concentration. For body weight, our study quantified a threshold relationship between BMI and CKD, with increased risk at BMI above 25 kg/m2. The causal relationship between nephrolithiasis and CKD were reported in previous studies, but our study confirmed the causal links between the two for the first time.Implication of all the available evidenceThis study makes a significant advance in comprehensively prioritising intervention targets for CKD in over 1.2 million participants. Our study presents causal evidence from both European and East Asian population samples, widening the generalisability of the causal atlas. Importantly, the prioritised risk factors are predominantly related to cardio-metabolic health, which supports the shared causal link between cardio-metabolic health and kidney function. Clinically, the high-quality evidence from this study highlights the value of exploring these causal factors in the general population and prioritizes drug targets and life-style interventions for CKD primary prevention, which could help reduce the global burden of CKD and its cardio-metabolic co-morbidities.

Rationale & Objective Mechanisms underlying the variable course of disease progression in patients with chronic kidney disease (CKD) are incompletely understood. The aim of this study was to identify novel biomarkers of adverse kidney outcomes and overall mortality, which may offer insights into pathophysiologic mechanisms. Study Design Metabolome-wide association study. Setting & Participants 5,087 patients with CKD enrolled in the observational German Chronic Kidney Disease Study. Exposures Measurements of 1,487 metabolites in urine. Outcomes End points of interest were time to kidney failure (KF), a combined end point of KF and acute kidney injury (KF+AKI), and overall mortality. Analytical Approach Statistical analysis was based on a discovery-replication design (ratio 2:1) and multivariable-adjusted Cox regression models. Results After a median follow-up of 4 years, 362 patients died, 241 experienced KF, and 382 experienced KF+AKI. Overall, we identified 55 urine metabolites whose levels were significantly associated with adverse kidney outcomes and/or mortality. Higher levels of C-glycosyltryptophan were consistently associated with all 3 main end points (hazard ratios of 1.43 [95% CI, 1.27-1.61] for KF, 1.40 [95% CI, 1.27-1.55] for KF+AKI, and 1.47 [95% CI, 1.33-1.63] for death). Metabolites belonging to the phosphatidylcholine pathway showed significant enrichment. Members of this pathway contributed to the improvement of the prediction performance for KF observed when multiple metabolites were added to the well-established Kidney Failure Risk Equation. Limitations Findings among patients of European ancestry with CKD may not be generalizable to the general population. Conclusions Our comprehensive screen of the association between urine metabolite levels and adverse kidney outcomes and mortality identifies metabolites that predict KF and represents a valuable resource for future studies of biomarkers of CKD progression.

Blood metabolites of the tryptophan pathway were found to be associated with kidney function and disease in observational studies. In order to evaluate causal relationship and direction, we designed a study using a bidirectional Mendelian randomization approach. The analyses were based on published summary statistics with study sizes ranging from 1,960 to 133,413. After correction for multiple testing, results provided no evidence of an effect of metabolites of the tryptophan pathway on estimated glomerular filtration rate (eGFR). Conversely, lower eGFR was related to higher levels of four metabolites: C-glycosyltryptophan (effect estimate = − 0.16, 95% confidence interval [CI] (− 0.22; − 0.1); p = 9.2e−08), kynurenine (effect estimate = − 0.18, 95% CI (− 0.25; − 0.11); p = 1.1e−06), 3-indoxyl sulfate (effect estimate = − 0.25, 95% CI (− 0.4; − 0.11); p = 6.3e−04) and indole-3-lactate (effect estimate = − 0.26, 95% CI (− 0.38; − 0.13); p = 5.4e−05). Our study supports that lower eGFR causes higher blood metabolite levels of the tryptophan pathway including kynurenine, C-glycosyltryptophan, 3-indoxyl sulfate, and indole-3-lactate. These findings aid the notion that metabolites of the tryptophan pathway are a consequence rather than a cause of reduced eGFR. Further research is needed to specifically examine relationships with respect to chronic kidney disease (CKD) progression among patients with existing CKD.

Background and Aims Neck circumference (NC) is an approximator of upper body subcutaneous fat tissue and a marker of obesity. It has been shown to be associated with cardiovascular risk factors and incident chronic kidney disease (CKD). In CKD patients, the impact on cardiovascular events and all cause death has not been fully elucidated yet. The prognostic impact on these outcomes in a representative cohort of adult patients with moderate CKD of Caucasian origin was investigated here. Method We used data from the GCKD study, a German multi-centric prospective observational cohort study of 5217 adults with moderate chronic kidney disease, defined as eGFR 30–60 mL/min/1.73 m2 or eGFR >60 mL/min/1.73 m2 and significant proteinuria (albuminuria >300 mg/g creatinine or proteinuria >500 mg/g creatinine). Exclusion criteria were active malignancy, heart failure NYHA class IV, organ transplantation, and non-Caucasian origin. NC was measured repeatedly (annually, except at first year of follow-up) during the study, therefore, the mean value was analyzed. We report data from the 4-year follow-up visit regarding 1) a combined endpoint of non-fatal myocardial infarction, non-fatal stroke, cardiovascular death, and peripheral artery disease event (amputation or revascularization) and 2) all-cause death as another endpoint. Cox proportional hazard regression was used to calculate hazard ratios (HR) with 95% CIs. In univariate analysis, ordinal regression with quintiles of NC was applied. Results NC was accrued in 4453 participants and analyzed. NC overall was 40±5 cm (43±4 cm in men and 37±4 cm in women, p Conclusion In patients with chronic kidney disease, we found higher NC to be associated with increased cardiovascular event risk, but not all-cause death, after adjustment for age, sex and BMI. The risk of cardiovascular outcomes and overall mortality was consistently lower in women. Our analysis supports evidence, that upper body subcutaneous adipose tissue might be an independent contributor to cardiovascular event risk.

Identification of chronic kidney disease patients at risk of progressing to end-stage renal disease (ESRD) is essential for treatment decision-making and clinical trial design. Here, we explored whether proton nuclear magnetic resonance (NMR) spectroscopy of blood plasma improves the currently best performing kidney failure risk equation, the so-called Tangri score. Our study cohort comprised 4640 participants from the German Chronic Kidney Disease (GCKD) study, of whom 185 (3.99%) progressed over a mean observation time of 3.70 ± 0.88 years to ESRD requiring either dialysis or transplantation. The original four-variable Tangri risk equation yielded a C statistic of 0.863 (95% CI, 0.831-0.900). Upon inclusion of NMR features by state-of-the-art machine learning methods, the C statistic improved to 0.875 (95% CI, 0.850-0.911), thereby outperforming the Tangri score in 94 out of 100 subsampling rounds. Of the 24 NMR features included in the model, creatinine, high-density lipoprotein, valine, acetyl groups of glycoproteins, and Ca2+-EDTA carried the highest weights. In conclusion, proton NMR-based plasma fingerprinting improved markedly the detection of patients at risk of developing ESRD, thus enabling enhanced patient treatment.

IMPORTANCE Increased free thyroxine (FT4) and decreased thyrotropin are associated with increased risk of atrial fibrillation (AF) in observational studies, but direct involvement is unclear.OBJECTIVE To evaluate the potential direct involvement of thyroid traits on AF.DESIGN, SETTING. AND PARTICIPANTS Study-level mendelian randomization (MR) included 11 studies, and summary-level MR included 55 114 AF cases and 482 295 referents, all of European ancestry.EXPOSURES Genomewide significant variants were used as instruments for standardized FT4 and thyrotropin levels within the reference range, standardized triiodothyronine (FT3):FT4 ratio, hypothyroidism, standardized thyroid peroxidase antibody levels, and hyperthyroidism. Mendelian randomization used genetic risk scores in study-level analysis or individual single-nucleotide polymorphisms in 2-sample MR for the summary-level data.MAIN OUTCOMES AND MEASURES Prevalent and incident AF.RESULTS The study-level analysis included 7679 individuals with AF and 49 233 referents (mean age [standard error], 62 [3] years; 15 859 men [29.7%]). In study-level random-effects meta-analysis, the pooled hazard ratio of FT4 levels (nanograms per deciliter) for incident AF was 1.55 (95% CI, 1.09-2.20; P = .02; I-2= 76%) and the pooled odds ratio (OR) for prevalent AF was 2.80 (95% CI, 1.41-5.54; P = .003; I-2 = 64%) in multivariable-adjusted analyses. The FT4 genetic risk score was associated with an increase in FT(4 )by 0.082 SD (standard error, 0.007; P CONCLUSIONS AND RELEVANCE Genetically increased FT3:FT(4 )ratio and hyperthyroidism, but not FT4 within the reference range, were associated with increased AF, and increased thyrotropin within the reference range and hypothyroidism were associated with decreased AF, supporting a pathway involving the pituitary-thyroid-cardiac axis.

BACKGROUND AND OBJECTIVES: Uromodulin is exclusively produced by tubular epithelial cells and released into urine and serum. Higher serum uromodulin has been associated with lower risk for kidney failure in Chinese patients with CKD and with lower risk for mortality in the elderly and in patients undergoing coronary angiography. We hypothesized that lower serum uromodulin is associated with mortality, cardiovascular events, and kidney failure in white patients with CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We measured serum uromodulin in 5143 participants enrolled in the German CKD (GCKD) study. The associations of baseline serum uromodulin with all-cause mortality, major adverse cardiovascular events (MACE; a composite of cardiovascular mortality, nonfatal myocardial infarction or stroke, or incident peripheral vascular disease), and kidney failure (dialysis or transplantation) were evaluated using multivariable Cox proportional hazard regression analyses in a cohort study design, adjusting for demographics, eGFR, albuminuria, cardiovascular risk factors, and medication. RESULTS: The mean age of participants was 60±12 years, 60% were male. Mean serum uromodulin concentration was 98±60 ng/ml, eGFR was 49±18 ml/min per 1.73 m(2), and 78% had eGFR

We evaluated genetics of hyperuricemia and gout, their interaction with kidney function and medication intake in chronic kidney disease (CKD) patients. Genome-wide association studies (GWAS) of urate and gout were performed in 4941 CKD patients in the German Chronic Kidney Disease (GCKD) study. Effect estimates of 26 known urate-associated population-based single nucleotide polymorphisms (SNPs) were examined. Interactions of urate-associated variants with urate-altering medications and clinical characteristics of gout were evaluated. Genome-wide significant associations with serum urate and gout were identified for known loci at SLC2A9 and ABCG2, but not for novel loci. Effects of the 26 known SNPs were of similar magnitude in CKD patients compared to population-based individuals, except for SNPs at ABCG2 that showed greater effects in CKD. Gene-medication interactions were not significant when accounting for multiple testing. Associations with gout in specific joints were significant for SLC2A9 rs12498742 in wrists and midfoot joints. Known genetic variants in SLC2A9 and ABCG2 were associated with urate and gout in a CKD cohort, with effect sizes for ABCG2 significantly greater in CKD compared to the general population. CKD patients are at high risk of gout due to reduced kidney function, diuretics intake and genetic predisposition, making treatment to target challenging.

Caliskan, Salim/0000-0002-3316-8032 WOS:000458823600014 PubMed ID: 30140068 BACKGROUND: Genome-wide association studies (GWAS) in healthy populations have identified variants associated with erythrocyte traits, but genetic causes of hemoglobin variation in children with CKD are incompletely understood. METHODS: The Pediatric Investigation of Genetic Factors Linked with Renal Progression (PediGFR) Consortium comprises three pediatric CKD cohorts: Chronic Kidney Disease in Children (CKiD), Effect of Strict Blood Pressure Control and ACE Inhibition on the Progression of CRF in Pediatric Patients (ESCAPE), and Cardiovascular Comorbidity in Children with CKD (4C). We performed crosssectional and longitudinal association studies of single-nucleotide polymorphisms (SNPs) in 1125 patients. RESULTS: Children of European (n = 725) or Turkish (n = 400) ancestry (EA or TA) were included. In cross-sectional analysis, two SNPs (rs10758658 and rs12718597) previously associated with RBC traits were significantly associated with hemoglobin levels in children of EA and TA. In longitudinal analysis, SNP rs2540917 was nominally associated with hemoglobin in EA and TA children. CONCLUSIONS: SNPs associated with erythrocyte traits in healthy populations were marginally significant for an association with hemoglobin. Further analyses/replication studies are needed in larger CKD cohorts to investigate SNPs of unknown significance associated with hemoglobin. Functional studies will be required to confirm that the observed associations between SNPs and clinical phenotype are causal. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)United States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK); Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD); National Heart, Lung, and Blood InstituteUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Heart Lung & Blood Institute (NHLBI) [U01-DK-66143, U01-DK-66174, U01DK-082194, U01-DK-66116]; European Commission Fifth Framework ProgrammeEuropean Union (EU) [QLRT-2001-00908]; Boehringer Ingelheim FoundationBoehringer Ingelheim; Kuratorium fur Dialyse und Nierentransplantation e.V.; Baxter Extramural Grant Program; ERA-EDTA Research Programme; KfH Foundation for Preventive Medicine; German Federal Ministry of Education and ResearchFederal Ministry of Education & Research (BMBF) [01EO0802]; NIDDKUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK) [RO1-DK-082394]; EU 7th Framework Programme (EURenOmics) [2012-305608]; National Institutes of Health (NIH)/NIDDKUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK) [K23-DK-084116]; German Research FoundationGerman Research Foundation (DFG) [CRC 1140]; Amgen, Inc.Amgen; NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASESUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USANIH National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK) [U01DK066174, U01DK066174, U01DK066174, U01DK066143, U01DK066174, U01DK066116, U01DK066116, U01DK082194, U01DK066143, U01DK066174, U01DK066174, U01DK066116, U01DK066143, U01DK066174, U01DK082194, U01DK082194, U01DK082194, U01DK082194, U01DK082194, U01DK066143, U01DK066174, U01DK066116, U01DK066174, U01DK066143, U01DK066116, U01DK066143, U01DK066116, U01DK066174, U01DK066143, U01DK066116, U01DK066174, U01DK066174, U01DK082194, U01DK066143, U01DK066143, U01DK082194, U01DK066143, U01DK066116, U01DK066116, U01DK066174, U01DK066143, U01DK066116, U01DK082194, U01DK066116, U01DK066174, U01DK066116, U01DK066143, U01DK066116, U01DK066174, U01DK066116, U01DK066143, U01DK066116, U01DK066116, U01DK066174, U01DK066174, U01DK082194, U01DK066143, U01DK066174, U01DK066174, U01DK082194, U01DK066116, U01DK066116, U01DK082194, U01DK066143, U01DK066143, U01DK066143, U01DK066174, U01DK066143, U01DK066174, U01DK066116, U01DK066174, U01DK066143, U01DK066174, U01DK066174, U01DK066143, U01DK082194, U01DK082194, U01DK066143, U01DK066143, U01DK066143] Funding Source: NIH RePORTER The CKiD Study is supported by grants from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), with additional funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the National Heart, Lung, and Blood Institute (U01-DK-66143, U01-DK-66174, U01DK-082194, and U01-DK-66116). The CKID website is located at http://www.statepi.jhsph.edu/ckid.The ESCAPE trial and the 4C Study were conducted by the ESCAPE Clinical Research Network. The ESCAPE Trial was supported by grants from the European Commission Fifth Framework Programme (QLRT-2001-00908), Boehringer Ingelheim Foundation, Kuratorium fur Dialyse und Nierentransplantation e.V., and the Baxter Extramural Grant Program. Support for the 4C Study was received from the ERA-EDTA Research Programme, the KfH Foundation for Preventive Medicine and the German Federal Ministry of Education and Research (reference number: 01EO0802). The genotyping data utilized for the PediGFR Consortium studies (CKiD, 4C, and ESCAPE) were supported by NIDDK Grant No. RO1-DK-082394. Additional support was provided by the EU 7th Framework Programme (EURenOmics, Grant 2012-305608). M.A.A. was supported by the National Institutes of Health (NIH)/NIDDK (K23-DK-084116). The work of M.W. and A.K was supported by the CRC 1140 of the German Research Foundation. M.A.A. and S.L.F. were supported by an unrestricted grant from Amgen, Inc.

Fructosamine and glycated albumin are potentially useful alternatives to hemoglobin A1c (HbA1c) as diabetes biomarkers. The genetic determinants of fructosamine and glycated albumin, however, are unknown. We performed genome-wide association studies of fructosamine and glycated albumin among 2,104 black and 7,647 white participants without diabetes in the Atherosclerosis Risk in Communities (ARIC) Study and replicated findings in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Among whites, rs34459162, a novel missense single nucleotide polymorphism (SNP) in RCN3, was associated with fructosamine (P = 5.3 × 10−9) and rs1260236, a known diabetes-related missense mutation in GCKR, was associated with percent glycated albumin (P = 5.9 × 10−9) and replicated in CARDIA. We also found two novel associations among blacks: an intergenic SNP, rs2438321, associated with fructosamine (P = 6.2 × 10−9), and an intronic variant in PRKCA, rs59443763, associated with percent glycated albumin (P = 4.1 × 10−9), but these results did not replicate. Few established fasting glucose or HbA1c SNPs were also associated with fructosamine or glycated albumin. Overall, we found genetic variants associated with the glycemic information captured by fructosamine and glycated albumin as well as with their nonglycemic component. This highlights the importance of examining the genetics of hyperglycemia biomarkers to understand the information they capture, including potential glucose-independent factors.

RATIONALE & OBJECTIVE: Stratification of chronic kidney disease (CKD) patients at risk for progressing to end-stage kidney disease (ESKD) requiring kidney replacement therapy (KRT) is important for clinical decision-making and trial enrollment. STUDY DESIGN: Four independent prospective observational cohort studies. SETTING & PARTICIPANTS: The development cohort was comprised of 4,915 CKD patients and three independent validation cohorts were comprised of a total of 3,063. Patients were followed-up for approximately five years. NEW PREDICTORS & ESTABLISHED PREDICTORS: 22 demographic, anthropometric and laboratory variables commonly assessed in CKD patients. OUTCOMES: Progression to ESKD requiring KRT. ANALYTICAL APPROACH: A Least Absolute Shrinkage and Selection Operator (LASSO) Cox proportional hazards model was fit to select laboratory variables that best identified patients at high risk for ESKD. Model discrimination and calibration were assessed and compared against the 4-variable Tangri (T4) risk equation. Both used a resampling approach within the development cohort and in the validation cohorts using cause-specific concordance (C) statistics, net reclassification improvement, and calibration graphs. RESULTS: The newly derived 6-variable (Z6) risk score included serum creatinine, albumin, cystatin C and urea, as well as hemoglobin and the urine albumin-to-creatinine ratio. Based on the resampling approach, Z6 achieved a median C value of 0.909 (95% CI, 0.868-0.937) at two years after the baseline visit, whereas the T4 achieved a median C value of 0.855 (95% CI, 0.799-0.915). In the three independent validation cohorts, Z6 C values were 0.894, 0.921, and 0.891, whereas the T4 C values were 0.882, 0.913, and 0.862. LIMITATIONS: The Z6 was both derived and tested only in White European cohorts. CONCLUSIONS: A new risk equation, based on six routinely available laboratory tests facilitates identification of patients with CKD who are at high risk of progressing to ESKD.

Chronic kidney disease (CKD) is defined by reduced estimated glomerular filtration rate (eGFR). Previous genetic studies have implicated regulatory mechanisms contributing to CKD. Here we present epigenome-wide association studies of eGFR and CKD using whole-blood DNA methylation of 2264 ARIC Study and 2595 Framingham Heart Study participants to identify epigenetic signatures of kidney function. Of 19 CpG sites significantly associated (P PTPN6/PHB2, ANKRD11, and TNRC18 map to active enhancers in kidney cortex. At PTPN6/PHB2 cg19942083, methylation in kidney cortex associates with lower renal PTPN6 expression, higher eGFR, and less renal fibrosis. The regions containing the 243 eGFR-associated (P P

The International Society of Nephrology has adopted a proactive approach to defining the current state of kidney care and unmet needs through a multifaceted Closing the Gaps initiative. As part of this initiative, the International Society of Nephrology convened a meeting of experts to develop an approach to tackle acute kidney injury and chronic kidney disease (CKD). This manuscript expands on the recently published International Society of Nephrology CKD Roadmap and reports on the discussions of the working group assigned to the task of reviewing the global impact of complication of CKD. The working group defined the following goals: Goal 1: Optimize the management of anemia and endocrine and metabolic abnormalities associated with CKD. The impact of these conditions at a global level is not well understood, particularly in regions where renal replacement therapy is not readily available. Some treatment regimens may be affordable in low- and middle-income countries and if implemented, could have an impact on the burden of suffering associated with CKD. Goal 2: Improve the prevention and management of cardiovascular complications linked to CKD. Most research on cardiovascular complications of CKD has focused on atherosclerotic diseases (myocardial infarction, ischemic stroke, and peripheral gangrene). There has been growing recognition that other forms of cardiovascular diseases, such as heart failure, valvular disease and arrhythmias, have a major impact on patient outcomes. Much less is known about the mechanisms and treatment of these non-atherosclerotic complications. Goal 3: Improve the diagnosis and management of symptoms associated with CKD. Symptom management is one of the greatest challenges in the management of CKD, with limited knowledge about the mechanisms associated with the development of these common problems and how best to characterize them into usable clinical phenotypes. Improved understanding of the complications of CKD may alleviate suffering and prolong life among millions of people worldwide both in developed countries and in regions where renal replacement therapy is not widely available.

Context Cardiovascular outcomes in mild thyroid dysfunction (treatment controversial) and moderate or severe dysfunction (treatment standard) remain uncertain. Objective To examine cross-sectional and prospective associations of thyroid function with cardiovascular risk factors and events. Design In the Atherosclerosis Risk in Communities Study, we measured concentrations of thyrotropin, free thyroxine, and total triiodothyronine (T3) in stored serum samples originally collected in 1990-1992. We used multivariable linear regression to assess cross-sectional associations of thyroid function with cardiovascular risk factors and Cox regression to assess prospective associations with cardiovascular events. Follow-up occurred through 31 December 2014. Setting General community. Participants Black and white men and women from the United States, without prior myocardial infarction (MI), stroke, or heart failure. Main outcomes and measures Cross-sectional outcomes were blood pressure, glycemic markers, and blood lipids. Prospective outcomes were adjudicated fatal and nonfatal MI and stroke. Results Among 11,359 participants (57 ± 6 years, 58% women), thyroid function was more strongly associated with blood lipids than blood pressure or glycemic measures. Mean adjusted differences in low-density lipoprotein cholesterol were +15.1 (95% confidence interval: 10.5 to 19.7) and +3.2 (0.0 to 6.4) mg/dL in those with moderate/severe and mild chemical hypothyroidism, relative to euthyroidism; an opposite pattern was seen in hyperthyroidism. Similar differences were seen in triglycerides and non-high-density lipoprotein cholesterol. With a 22.5-year median follow-up, 1102 MIs and 838 strokes occurred, with similar outcomes among baseline thyroid function groups and by T3 concentrations. Conclusions Hypothyroidism is associated with hyperlipidemia, but the magnitude is small in mild chemical hypothyroidism, and cardiovascular outcomes are similar between thyroid function groups.

Genetic research in nephrology is rapidly advancing. Key studies published in 2020 demonstrate that genetic findings can provide new tools for patient diagnosis and risk stratification as well as important insights into kidney physiology and disease mechanisms that could potentially lead to novel therapies.

International audience; BACKGROUNDProteinuria is considered an unfavorable clinical condition that accelerates renal and cardiovascular disease. However, it is not clear whether all forms of proteinuria are damaging. Mutations in CUBN cause Imerslund-Gräsbeck syndrome (IGS), which is characterized by intestinal malabsorption of vitamin B12 and in some cases proteinuria. CUBN encodes for cubilin, an intestinal and proximal tubular uptake receptor containing 27 CUB domains for ligand binding.METHODSWe used next-generation sequencing for renal disease genes to genotype cohorts of patients with suspected hereditary renal disease and chronic proteinuria. CUBN variants were analyzed using bioinformatics, structural modeling, and epidemiological methods.RESULTSWe identified 39 patients, in whom biallelic pathogenic variants in the CUBN gene were associated with chronic isolated proteinuria and early childhood onset. Since the proteinuria in these patients had a high proportion of albuminuria, glomerular diseases such as steroid-resistant nephrotic syndrome or Alport syndrome were often the primary clinical diagnosis, motivating renal biopsies and the use of proteinuria-lowering treatments. However, renal function was normal in all cases. By contrast, we did not found any biallelic CUBN variants in proteinuric patients with reduced renal function or focal segmental glomerulosclerosis. Unlike the more N-terminal IGS mutations, 37 of the 41 proteinuria-associated CUBN variants led to modifications or truncations after the vitamin B12-binding domain. Finally, we show that 4 C-terminal CUBN variants are associated with albuminuria and slightly increased GFR in meta-analyses of large population-based cohorts.CONCLUSIONCollectively, our data suggest an important role for the C-terminal half of cubilin in renal albumin reabsorption. Albuminuria due to reduced cubilin function could be an unexpectedly common benign condition in humans that may not require any proteinuria-lowering treatment or renal biopsy.FUNDINGATIP-Avenir program, Fondation Bettencourt-Schueller (Liliane Bettencourt Chair of Developmental Biology), Agence Nationale de la Recherche (ANR) Investissements d'avenir program (ANR-10-IAHU-01) and NEPHROFLY (ANR-14-ACHN-0013, to MS), Steno Collaborative Grant 2018 (NNF18OC0052457, to TSA and MS), Heisenberg Professorship of the German Research Foundation (KO 3598/5-1, to AK), Deutsche Forschungsgemeinschaft (DFG) Collaborative Research Centre (SFB) KIDGEM 1140 (project 246781735, to CB), and Federal Ministry of Education and Research (BMB) (01GM1515C, to CB).

Background1,5-Anhydroglucitol (1,5-AG) is a novel biomarker of glycemic control proposed to monitor recent hyperglycemic excursions in persons with diabetes. The clinical utility of 1,5-AG outside of diagnosed diabetes is unclear, but it may identify people at high risk for diabetes and its complications. We compared associations of 1,5-AG with 2-h glucose for risk of major clinical complications.Research Design and MethodsWe prospectively followed 6644 Atherosclerosis Risk in Communities (ARIC) Study participants without diagnosed diabetes for incident diagnosed diabetes, chronic kidney disease, cardiovascular disease, and all-cause mortality for ∼20 years. We assessed associations of 1,5-AG and 2-h glucose (modeled categorically and continuously with restricted cubic splines) with adverse outcomes using Cox models and evaluated improvement in risk discrimination using Harrell’s c-statistic.Results1,5-AG ConclusionsIn this community-based population without diagnosed diabetes, low 1,5-AG was modestly associated with major clinical outcomes and did not outperform 2-h glucose.

ObjectiveTo evaluate the bi-directional causal relation between kidney function and blood pressure.DesignMendelian randomisation study.SettingWe performed two-sample Mendelian randomisation analyses. Genetic instruments of kidney function traits were selected from summary statistics of genome-wide association studies (GWAS) of glomerular filtration rate estimated from serum creatinine (eGFRcr) and blood urea nitrogen (BUN) and were required to be associated with both eGFRcr and BUN to ensure that the instruments were more likely to represent the underlying kidney function. Genetic instruments of blood pressure were selected from summary statistics of GWAS of systolic and diastolic blood pressure. We investigated Mendelian randomisation hypothesis using several alternative approaches, including methods that are most robust to the presence of horizontal pleiotropy.ParticipantsThe summary statistics of eGFRcr included 567,460 participants from 54 cohorts, and the summary statistics of BUN included 243,031 participants from 48 cohorts from the Chronic Kidney Disease Genetics (CKDGen) Consortium. The summary statistics of systolic and diastolic blood pressure included 757,601 participants from the UK Biobank and 78 cohorts from the International Consortium for Blood Pressure (ICBP).ResultsSignificant evidence supported the causal effects of higher kidney function on lower blood pressure with multiple methods. Based on the mode-based Mendelian randomisation analysis approach, known for its robustness to the presence of pleiotropic effect, the effect estimate for 1 SD higher in eGFRcr was −0.17 SD unit (95 % CI: −0.09 to −0.24) in systolic blood pressure (SBP) and −0.15 SD unit (95% CI: −0.07 to −0.22) in diastolic blood pressure (DBP). In contrast, the causal effects of blood pressure on kidney function were not statistically significant.ConclusionsMendelian randomisation analyses support causal effects of higher kidney function on lower blood pressure. These results suggest preventing kidney function decline can reduce the public health burden of hypertension.

In panic disorder (PD), epigenetic mechanisms such as DNA methylation of candidate genes have been suggested to play a key role at the intersection of genetic and environmental factors. On an epigenome-wide level, however, only two studies in PD patients have been published so far, while to date no study has intra-individually analyzed dynamic epigenetic correlates of treatment-response in PD on a DNA methylome level. Here, an epigenome-wide association study (EWAS) was performed in a sample of 57 PD patients and matched healthy controls using the Illumina MethylationEPIC BeadChip, along with a longitudinal approach assessing changes on the DNA methylome level corresponding to clinical effects of a manualized six-week cognitive-behavioral therapy (CBT) in PD. While no epigenome-wide significant hits could be discerned, top suggestive evidence was observed for decreased methylation in PD at cg19917903 in the Cilia and Flagella Associated Protein 46 (CFAP46) gene, and for an increase in methylation after CBT at cg06943668 in the Interleukin 1 Receptor Type 1 (IL1R1) gene in treatment responders to CBT. Additional exploratory analyses based on biological validity and a combined statistical/biological ranking point to further new potential PD risk genes such as the CCL4L1 or GMNN genes, and suggest dynamic methylation of, e.g., the ZFP622 and the SLC43A2 genes along with response to CBT. These EWAS and first longitudinal epigenome-wide pilot data in PD add to the emerging candidate gene-based body of evidence for epigenetic mechanisms to be involved in PD pathogenesis and to possibly constitute dynamic biological correlates of therapeutic interventions.

Chronic kidney disease (CKD), defined by low estimated glomerular filtration rate (eGFR), contributes to global morbidity and mortality. Here we conduct a transethnic Genome-Wide Association Study of eGFR in 280,722 participants of the Million Veteran Program (MVP), with replication in 765,289 participants from the Chronic Kidney Disease Genetics (CKDGen) Consortium. We identify 82 previously unreported variants, confirm 54 loci, and report interesting findings including association of the sickle cell allele of betaglobin among non-Hispanic blacks. Our transcriptome-wide association study of kidney function in healthy kidney tissue identifies 36 previously unreported and nine known genes, and maps gene expression to renal cell types. In a Phenome-Wide Association Study in 192,868 MVP participants using a weighted genetic score we detect associations with CKD stages and complications and kidney stones. This investigation reinterprets the genetic architecture of kidney function to identify the gene, tissue, and anatomical context of renal homeostasis and the clinical consequences of dysregulation., Persistently low levels of estimated glomerular filtration rate (eGFR) are a biomarker of chronic kidney disease. Here, the authors reinterpret the genetic architecture of kidney function across ancestries, to identify not only genes, but the tissue and anatomical contexts of renal homeostasis.

Nontraditional glycemic biomarkers, including fructosamine, glycated albumin, and 1,5-anhydroglucitol (1,5-AG) are potential alternatives or complement to traditional measures of hyperglycemia. Genetic variants are associated with these biomarkers, but the heritability, or extent to which genetics control their variation, is not known. We estimated pedigree-based, SNP-based, and bivariate heritabilities for traditional glycemic biomarkers (fasting glucose, HbA1c), and nontraditional biomarkers (fructosamine, glycated albumin, 1,5-AG) among white participants in the Atherosclerosis Risk in Communities (ARIC) Study (N = 400 first-degree relatives from sibships, N = 5,575 unrelated individuals). Pedigree-based heritabilities (representing heritability from the entire genome) for nontraditional biomarkers were substantial (0.44-0.55) and comparable to HbA1c (0.34); the fasting glucose estimate was nonsignificant. SNP-based heritabilities (representing heritability from common variants) were lower than pedigree-based heritabilities for all biomarkers. Bivariate heritabilities showed shared genetics between fructosamine and glycated albumin (0.46 pedigree-based, 1.00 SNP-based) and glycated albumin and 1,5-AG (0.50 pedigree-based, 0.47 SNP-based). Genetic factors contribute to a considerable proportion of the variance of fructosamine, glycated albumin, and 1,5-AG and a portion of this heritability likely comes from common variants.

Serum 1,5-anhydroglucitol (1,5-AG) is an emerging biomarker used to monitor glycemic control in persons with diabetes. We performed whole-exome sequencing, examining the association between rare, coding genetic variants and 1,5-AG among European ancestry (N = 6,589) and African ancestry (N = 2,309) participants without diagnosed diabetes in the Atherosclerosis Risk in Communities (ARIC) Study. Five variants representing 3 independent signals on chromosome 17 in SLC5A10, a glucose transporter not previously known to transport 1,5-AG, were associated with 1,5-AG levels up to 10.38 µg/mL lower per allele (1,5-AG range 3.4–32.8 µg/mL) in the European ancestry sample and validated in the African ancestry sample. Together these variants explained 6% of the variance in 1,5-AG. Two of these variants (rs61741107, p = 8.85E-56; rs148178887, p = 1.13E-36) were rare, nonsynonymous, and predicted to be damaging or deleterious by multiple algorithms. Gene-based SKAT-O analysis supported these results (SLC5A10 p = 5.13E-64 in European ancestry, validated in African ancestry, p = 0.006). Interestingly, these novel variants are not associated with other biomarkers of hyperglycemia or diabetes (p > 0.2). The large effect sizes and protein-altering, multiple independent signals suggest SLC5A10 may code for an important transporter of 1,5-AG in the kidney, with a potential nonglucose-related effect on 1,5-AG, impacting its clinical utility as a diabetes biomarker in this subpopulation.

Background: Evidence is mounting that intraprostatic inflammation influences prostate cancer development. Uric acid crystals depositing in the prostate could result in injury and inflammation, increasing prostate cancer risk. Methods: Included were 6,574 men ages 45–64 years who enrolled in the Atherosclerosis Risk in Communities study in 1987 to 1989. We used Cox proportional hazards regression to estimate the association of serum urate concentration alone and to improve accuracy, jointly with a genetic risk score (GRS, N = 4,983) derived from variants predictive of urate concentration, with prostate cancer (N = 813) risk. Results: Serum urate concentration or joint categories of urate concentration and GRS were not associated with prostate cancer risk (Ptrend for quartiles = 0.3). Results were generally similar by race and after excluding users of medications that influence uric acid. Conclusions: Serum urate alone and with a urate-associated GRS were not associated with prostate cancer risk. Impact: It is unlikely that circulating urate concentration influences prostate cancer development.

BACKGROUND AND OBJECTIVES: Data are scarce on blood metabolite associations with proteinuria, a strong risk factor for adverse kidney outcomes. We sought to investigate associations of proteinuria with serum metabolites identified using untargeted profiling in populations with CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Using stored serum samples from the African American Study of Kidney Disease and Hypertension (AASK; n=962) and the Modification of Diet in Renal Disease (MDRD) study (n=620), two rigorously conducted clinical trials with per-protocol measures of 24-hour proteinuria and GFR, we evaluated cross-sectional associations between urine protein-to-creatinine ratio and 637 known, nondrug metabolites, adjusting for key clinical covariables. Metabolites significantly associated with proteinuria were tested for associations with CKD progression. RESULTS: In the AASK and the MDRD study, respectively, the median urine protein-to-creatinine ratio was 80 (interquartile range [IQR], 28–359) and 188 (IQR, 54–894) mg/g, mean age was 56 and 52 years, 39% and 38% were women, 100% and 7% were black, and median measured GFR was 48 (IQR, 35–57) and 28 (IQR, 18–39) ml/min per 1.73 m(2). Linear regression identified 66 serum metabolites associated with proteinuria in one or both studies after Bonferroni correction (P

Elevated serum urate levels can cause gout, an excruciating disease with suboptimal treatment. Previous GWAS identified common variants with modest effects on serum urate. Here we report large-scale whole-exome sequencing association studies of serum urate and kidney function among ≤19,517 European ancestry and African-American individuals. We identify aggregate associations of low-frequency damaging variants in the urate transporters SLC22A12 (URAT1; p = 1.3 × 10−56) and SLC2A9 (p = 4.5 × 10−7). Gout risk in rare SLC22A12 variant carriers is halved (OR = 0.5, p = 4.9 × 10−3). Selected rare variants in SLC22A12 are validated in transport studies, confirming three as loss-of-function (R325W, R405C, and T467M) and illustrating the therapeutic potential of the new URAT1-blocker lesinurad. In SLC2A9, mapping of rare variants of large effects onto the predicted protein structure reveals new residues that may affect urate binding. These findings provide new insights into the genetic architecture of serum urate, and highlight molecular targets in SLC22A12 and SLC2A9 for lowering serum urate and preventing gout., Elevated serum urate levels are a risk factor for gout. Here, Tin et al. perform whole-exome sequencing in 19,517 individuals and detect low-frequency genetic variants in urate transporter genes, SLC22A12 and SLC2A9, associated with serum urate levels and confirm their damaging nature in vitro and in silico.