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Background: Truncating variants in filamin C (FLNC) can cause arrhythmogenic cardiomyopathy (ACM) through haploinsufficiency. Noncanonical splice-altering variants may contribute to this phenotype. Objective: The purpose of this study was to investigate the clinical and functional consequences of a recurrent FLNC intronic variant of uncertain significance (VUS), c.970-4A>G. Methods: Clinical data in 9 variant heterozygotes from 4 kindreds were obtained from 5 tertiary health care centers. We used in silico predictors and functional studies with peripheral blood and patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Isolated RNA was studied by reverse transcription polymerase chain reaction. iPSC-CMs were further characterized at baseline and after nonsense-mediated decay (NMD) inhibition, using quantitative polymerase chain reaction (qPCR), RNA-sequencing, and cellular electrophysiology. American College of Medical Genetics and Genomics (ACMG) criteria were used to adjudicate variant pathogenicity. Results: Variant heterozygotes displayed a spectrum of disease phenotypes, spanning from mild ventricular dysfunction with palpitations to severe ventricular arrhythmias requiring device shocks or progressive cardiomyopathy requiring heart transplantation. Consistent with in silico predictors, the c.970-4A>G FLNC variant activated a cryptic splice acceptor site, introducing a 3-bp insertion containing a premature termination codon. NMD inhibition upregulated aberrantly spliced transcripts by qPCR and RNA-sequencing. Patch clamp studies revealed irregular spontaneous action potentials, increased action potential duration, and increased sodium late current in proband-derived iPSC-CMs. These findings fulfilled multiple ACMG criteria for pathogenicity. Conclusion: Clinical, in silico, and functional evidence support the prediction that the intronic c.970-4A>G VUS disrupts splicing and drives ACM, enabling reclassification from VUS to pathogenic.

BACKGROUNDMineralocorticoid receptor (MR) activation induces fibrosis. Urinary proteomic profiling (UPP) detects thousands of sequenced peptides, mainly derived from collagen. No previous study applied UPP to generate insights in the antifibrotic actions of MR antagonism.METHODSBased on urine sample availability, subsets of the open HOMAGE trial (n=290; 23.8% women; median age: 73 years) and the double-blind PRIORITY trial (n=110; 21.8% women; 64 years) were analyzed as discovery and replication data sources. In the open HOMAGE trial, patients at risk of heart failure were randomized to usual therapy or usual therapy combined with spironolactone 25-50 mg/d. In the double-blind PRIORITY trial, type-2 diabetic patients with normal renal function were randomized to placebo or spironolactone 25 mg/d, both given on top of usual therapy. UPP relied on capillary electrophoresis coupled with mass spectrometry. In HOMAGE, the PICP/CITP ratio was calculated from serum PICP and serum CITP, which are markers of type-1 collagen synthesis and degradation, respectively. After rank-normalization of the biomarker distributions, between-group differences in the biomarker changes were analyzed by multivariable models. Correlations between the changes in urinary peptides and in serum CITP, derived from mature type-1 collagen, were compared between groups, using Fisher Z transform.RESULTSIn the HOMAGE and PRIORITY analytical subsets, patients had detectable signals of 1498 urinary peptides. Follow-up totaled 9 months in HOMAGE and was 30 months (median) in PRIORITY. All changes in urinary peptides that remained significantly different (PP≤0.0129). Correlations between changes from baseline to follow-up in urinary type-1 collagen fragments and CITP were positive often reaching significance if fragments increased during follow-up, but were nonsignificant if fragments decreased during follow-up. There were no between-group differences in these correlations.CONCLUSIONSMR antagonism predominantly reduces collagen-derived urinary peptides. Inhibition of collagen synthesis by lowering the amount available for breakdown may be a contributing mechanism.Clinical PerspectiveWhat Is New?Few studies addressed the association between urinary and serum markers of fibrosis and how MR antagonism influences urinary peptides derived from collagen.MR antagonism reduces collagen-derived urinary peptides. Inhibition of type-1 collagen synthesis by lowering the amount available for breakdown may be a contributing mechanism.Correlations between changes from baseline to follow-up in type-1 collagen and in CITP were positive if fragments increased during follow-up and nonsignificant if fragments decreased.What Are the Clinical Implications?Spironolactone inhibits fibrosis, supporting the use of MRAs in patients at risk of heart failure or chronic kidney disease.UPP profiling opens new research perspectives in documenting the antifibrotic properties of novel drug classes, such as nonsteroidal MR antagonists or sodium-glucose cotransporter-2 inhibitors.The development of novel medicines that would promote collagen degradation in addition to MRAs would strengthen the therapeutic armamentarium to modify fibrosis.GRAPHICAL ABSTRACT

BACKGROUND: Dilated cardiomyopathy (DCM) is a final common manifestation of heterogenous etiologies. Adverse outcomes highlight the need for disease stratification beyond ejection fraction. OBJECTIVES: The purpose of this study was to identify novel, reproducible subphenotypes of DCM using multiparametric data for improved patient stratification. METHODS: Longitudinal, observational UK-derivation (n = 426; median age 54 years; 67% men) and Dutch-validation (n = 239; median age 56 years; 64% men) cohorts of DCM patients (enrolled 2009-2016) with clinical, genetic, cardiovascular magnetic resonance, and proteomic assessments. Machine learning with profile regression identified novel disease subtypes. Penalized multinomial logistic regression was used for validation. Nested Cox models compared novel groupings to conventional risk measures. Primary composite outcome was cardiovascular death, heart failure, or arrhythmia events (median follow-up 4 years). RESULTS: In total, 3 novel DCM subtypes were identified: profibrotic metabolic, mild nonfibrotic, and biventricular impairment. Prognosis differed between subtypes in both the derivation (P < 0.0001) and validation cohorts. The novel profibrotic metabolic subtype had more diabetes, universal myocardial fibrosis, preserved right ventricular function, and elevated creatinine. For clinical application, 5 variables were sufficient for classification (left and right ventricular end-systolic volumes, left atrial volume, myocardial fibrosis, and creatinine). Adding the novel DCM subtype improved the C-statistic from 0.60 to 0.76. Interleukin-4 receptor-alpha was identified as a novel prognostic biomarker in derivation (HR: 3.6; 95% CI: 1.9-6.5; P = 0.00002) and validation cohorts (HR: 1.94; 95% CI: 1.3-2.8; P = 0.00005). CONCLUSIONS: Three reproducible, mechanistically distinct DCM subtypes were identified using widely available clinical and biological data, adding prognostic value to traditional risk models. They may improve patient selection for novel interventions, thereby enabling precision medicine. ispartof: JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY vol:79 issue:22 pages:2219-2232 ispartof: location:United States status: published

Background: Dilated cardiomyopathy (DCM) was considered a monogenetic disease that can be caused by over 60 genes. Evidence suggests that the combination of multiple pathogenic variants leads to greater disease severity and earlier onset. So far, not much is known about the prevalence and disease course of multiple pathogenic variants in patients with DCM. To gain insight into these knowledge gaps, we (1) systematically collected clinical information from a well-characterized DCM cohort and (2) created a mouse model. Methods: Complete cardiac phenotyping and genotyping was performed in 685 patients with consecutive DCM. Compound heterozygous digenic (LMNA [lamin]/titin deletion A-band) with monogenic (LMNA/wild-type) and wild-type/wild-type mice were created and phenotypically followed over time. Results: One hundred thirty-one likely pathogenic/pathogenic (LP/P) variants in robust DCM-associated genes were found in 685 patients with DCM (19.1%) genotyped for the robust genes. Three of the 131 patients had a second LP/P variant (2.3%). These 3 patients had a comparable disease onset, disease severity, and clinical course to patients with DCM with one LP/P. The LMNA/Titin deletion A-band mice had no functional differences compared with the LMNA/wild-type mice after 40 weeks of follow-up, although RNA-sequencing suggests increased cardiac stress and sarcomere insufficiency in the LMNA/Titin deletion A-band mice. Conclusions: In this study population, 2.3% of patients with DCM with one LP/P also have a second LP/P in a different gene. Although the second LP/P does not seem to influence the disease course of DCM in patients and mice, the finding of a second LP/P can be of importance to their relatives.

Instituto de Salud Carlos III (ISCIII), European Regional Development Fund/European Social Fund "A way to make Europe"/" Investing in your future" [PI18/0004, PI20/0320, PT17/0015/0043]; ISCIII; MCIN; Pro-CNIC Foundation; Severo Ochoa Centers of Excellence program [CEX2020-001041-S]; ISCIII [CM20/00101], Frutos F. de, Ochoa JP, Navarro-Peñalver M, Baas A, Bjerre JV, Zorio E, Méndez I, Lorca R, Verdonschot JAJ, García-Granja PE, Bilinska Z, Fatkin D, Fuentes-Cañamero ME, García-Pinilla JM, García-Álvarez MI, Girolami F, Barriales-Villa R, Díez-López C, Lopes LR, Wahbi K, García-Álvarez A, Rodríguez-Sánchez I, Rekondo-Olaetxea J, Rodríguez-Palomares JF, Gallego-Delgado M, Meder B, Kubanek M, Hansen FG, Restrepo-Córdoba MA, Palomino-Doza J, Ruiz-Guerrero L, Sarquella-Brugada G, Perez-Perez AJ, Bermúdez-Jiménez FJ, Ripoll-Vera T, Rasmussen TB, Jansen M, Sabater-Molina M, Elliot PM, Garcia-Pavia P; European Genetic Cardiomyopathies Initiative Investigators

BACKGROUND: Adipose tissue influences the expression and degradation of circulating biomarkers. We aimed to identify the biomarker profile and biological meaning of biomarkers associated with obesity to assess the effect of spironolactone on the circulating biomarkers and to explore whether obesity might modify the effect of spironolactone. METHODS AND RESULTS: Protein biomarkers (n = 276) from the Olink Proseek-Multiplex cardiovascular and inflammation panels were measured in plasma collected at baseline, 1 month and 9 months from the HOMAGE randomized controlled trial participants. Of the 510 participants, 299 had obesity defined as an increased waist circumference (≥102 cm in men and ≥88 cm in women). Biomarkers at baseline reflected adipogenesis, increased vascularization, decreased fibrinolysis, and glucose intolerance in patients with obesity at baseline. Treatment with spironolactone had only minor effects on this proteomic profile. Obesity modified the effect of spironolactone on systolic blood pressure (Pinteraction = 0.001), showing a stronger decrease of blood pressure in obese patients (-14.8 mm Hg 95% confidence interval -18.45 to -11.12) compared with nonobese patients (-3.6 mm Hg 95% confidence interval -7.82 to 0.66). CONCLUSIONS: Among patients at risk for heart failure, those with obesity have a characteristic proteomic profile reflecting adipogenesis and glucose intolerance. Spironolactone had only minor effects on this obesity-related proteomic profile, but obesity significantly modified the effect of spironolactone on systolic blood pressure. ispartof: JOURNAL OF CARDIAC FAILURE vol:28 issue:5 pages:778-786 ispartof: location:United States status: published

Aims: \ud Left ventricular ejection fraction (LVEF) can provide haemodynamic information and may influence the response to spironolactone and other heart failure (HF) therapies. We aimed to study patient characteristics and circulating protein associations with LVEF, and whether LVEF influenced the response to spironolactone.\ud \ud Methods and results: \ud HOMAGE enrolled patients aged >60 years at high risk of developing HF with a LVEF ≥45%. Overall, 527 patients were randomized to either spironolactone or standard of care for ≈9 months, and 276 circulating proteins were measured using Olink® technology. A total of 364 patients had available LVEF determined by the Simpson's biplane method. The respective LVEF tertiles were: tertile 1: 65% (n = 121). Patients with a LVEF >65% had smaller left ventricular chamber size and volumes, and lower natriuretic peptide levels. Compared to patients with a LVEF 65% had higher levels of circulating c-c motif chemokine ligand-23 and interleukin-8, and lower levels of tissue plasminogen activator, brain natriuretic peptide (BNP), S100 calcium binding protein A12, and collagen type I alpha 1 chain (COL1A1). Spironolactone significantly reduced the circulating levels of BNP and COL1A1 without significant treatment-by-LVEF heterogeneity: BNP change β = −0.36 log2 and COL1A1 change β = −0.16 log2 (p 0.1 for both). Spironolactone increased LVEF from baseline to month 9 by 1.1% (p = 0.007).\ud \ud Conclusion: \ud Patients with higher LVEF had higher circulating levels of chemokines and inflammatory markers and lower levels of stretch, injury, and fibrosis markers. Spironolactone reduced the circulating levels of natriuretic peptides and type 1 collagen, and increased LVEF.

Background: Osteosarcoma is the most common bone tumor in children and adolescents. Despite multiagent chemotherapy, only 71% of patients survives and these survivors often experience long-term toxicities. The main objective of this systematic review is to provide an overview of the discovery of novel associations of germline polymorphisms with treatment response and/or chemotherapy-induced toxicities in osteosarcoma.Methods: MEDLINE and Embase were systematically searched (2010-2020). Genetic association studies were included if they assessed >10 germline genetic variants in > 5 genes in relevant drug pathways or if they used a genotyping array or other large-scale genetic analysis. Quality was assessed using adjusted STrengthening the REporting of Genetic Association studies (STREGA)-guidelines. To find additional evidence for the identified associations, literature was searched to identify replication studies.Results: After screening 1533 articles, fifteen articles met our inclusion criteria. These range from studies focusing on genes in relevant pharmacokinetic pathways to whole genome sequencing. Eight articles reported on doxorubicin-induced cardiomyopathy. For seven genetic variants in CELF4, GPR35, HAS3, RARG, SLC22A17, SLC22A7 and SLC28A3, replication studies were performed, however without consistent results. Four small studies reported on bone marrow, nephro- and/or hepatotoxicity. Six studies included analysis for treatment efficacy. Genetic variants in ABCC3, ABCC5, FasL, GLDC, GSTP1 were replicated in studies using heterogeneous efficacy outcomes.Conclusions: Despite that results are promising, the majority of associations were poorly reproducible due to small patient cohorts. For the future, hypothesis-generating studies in large patient cohorts will be necessary, especially for cisplatin-induced ototoxicity as these are lacking. In order to form large patient cohorts, national and international collaboration will be essential.

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