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Metachromatic leukodystrophy (MLD) is a rare neurodegenerative lysosomal storage disease resulting from bi-allelic pathogenic variants in the ARSA gene. MLD is distinguished clinically based on the age of onset into late-infantile, juvenile, and adult. The late-infantile type is the most severe phenotype presenting with hypotonia, weakness, gait abnormalities, which progresses to mental and physical decline leading to early death. MLD is considered to be pan-ethnic and no founder variants have previously been described in the Ashkenazi Jewish population. We identified three unrelated individuals of Ashkenazi Jewish descent with homozygosity or compound heterozygosity for the c.178C>T (p.Arg60Trp) variant in the ARSA gene, with a phenotype consistent with late-infantile MLD. The carrier frequency was calculated among 93,293 individuals of Ashkenazi Jewish descent through the Dor Yeshorim screening program and found to have a carrier frequency on 1 in 1554 or 0.06%, which may be representative of a founder variant. Molecular protein modeling showed that the variant affects regional folding. Late-infantile MLD should be considered when the c.178C>T (p.Arg60Trp) variant in the ARSA gene is present in either the homozygous or the compound heterozygous states., (© 2024 Wiley Periodicals LLC.)

GBA mutations are major risk factors for Parkinson's disease (PD) and Dementia with Lewy Bodies (DLB), two common α-synucleinopathies associated with cognitive impairment. Here, we investigated the role of GBA mutations in cognitive decline by utilizing Gba L444P mutant mice, SNCA transgenic (tg), and Gba-SNCA double mutant mice. Notably, Gba mutant mice showed early cognitive deficits but no PD-like motor deficits up to 12 months old. Conversely, SNCA tg mice displayed age-related motor deficits but no cognitive abnormalities. Gba-SNCA mice exhibited exacerbated motor deficits and cognitive decline. Immunohistological analysis revealed cortical phospho-α-synuclein pathology in SNCA tg mice, which was exacerbated in Gba-SNCA mice, especially in layer 5 cortical neurons. Significantly, Gba mutant mice did not show α-synuclein pathology. Single-nucleus RNA sequencing of cortices instead uncovered selective synaptic vesicle cycle defects in excitatory neurons of Gba mutant and Gba-SNCA mice, via robust downregulation in gene networks regulating synapse vesicle cycle and synapse assembly. Meanwhile SNCA tg mice displayed broader synaptic changes. Immunohistochemical and electron microscopic analyses validated these findings. Together, our results indicate that Gba mutations, while exacerbating pre-existing α-synuclein aggregation and PD-like motor deficits, contribute to cognitive deficits through α-synuclein-independent mechanisms, likely involving dysfunction in synaptic vesicle endocytosis. Additionally, Gba-SNCA mice are a valuable model for studying cognitive and motor deficits in PD and DLB., Competing Interests: Conflicts of interest: Authors have no conflicts of interest to declare.

Gaucher disease type 1 (GD1) is known for phenotypic heterogeneity and varied natural history. Registrational clinical trials enrolled narrowly defined phenotypes, but greater diversity is encountered in clinical practice. We report real-world outcomes with long-term eliglustat treatment in adults with GD1 in the International Collaborative Gaucher Group Gaucher Registry. Among 5985 GD1 patients in the Registry as of January 6, 2023, 872 started eliglustat at ≥18 years old; of these, 469 met inclusion criteria. We compared clinical parameters at eliglustat initiation (i.e., baseline) and follow-up in treatment-naïve patients and used linear mixed models to estimate annual change from baseline in parameters among patients who switched to eliglustat after ≥1 year on enzyme replacement therapy. Over 4 years of follow-up in non-splenectomized treatment-naïve patients, hemoglobin and platelet count increased, liver and spleen volume decreased, and total lumbar spine bone mineral density (BMD) Z-score decreased slightly. Among non-splenectomized switch patients, on average, hemoglobin decreased -0.030 (95% CI: -0.053, -0.008) g/dL (N = 272) and platelet count increased 2.229 (95% CI: 0.751, 3.706) × 10 3 /mm 3 (N = 262) annually up to 10 years; liver volume decreased (-0.009 [95% CI: -0.015, -0.003] MN) (N = 102) and spleen volume remained stable (-0.070 [95% CI: -0.150, 0.010] MN) (N = 106) annually up to 7 years; and total lumbar spine BMD Z-score increased 0.041 (95% CI: 0.015, 0.066) (N = 183) annually up to 8 years. Among splenectomized switch patients, clinical parameters were stable over time. These long-term, real-world outcomes are consistent with the eliglustat clinical trials and emerging real-world experience across the GD phenotypic spectrum., (© 2024 The Authors. American Journal of Hematology published by Wiley Periodicals LLC.)

Background: Whole-exome sequencing (WES) is an effective tool for diagnosis in patients who remain undiagnosed despite a comprehensive clinical work-up. While WES is being used increasingly in pediatrics and oncology, it remains underutilized in non-oncological adult medicine, including in patients with liver disease, in part based on the faulty premise that adults are unlikely to harbor rare genetic variants with large effect size. Here, we aim to assess the burden of rare genetic variants underlying liver disease in adults at two major tertiary referral academic medical centers., Methods: WES analysis paired with comprehensive clinical evaluation was performed in fifty-two adult patients with liver disease of unknown etiology evaluated at two US tertiary academic health care centers., Findings: Exome analysis uncovered a definitive or presumed diagnosis in 33% of patients (17/52) providing insight into their disease pathogenesis, with most of these patients (12/17) not having a known family history of liver disease. Our data shows that over two-thirds of undiagnosed liver disease patients attaining a genetic diagnosis were being evaluated for cholestasis or hepatic steatosis of unknown etiology., Interpretation: This study reveals an underappreciated incidence and spectrum of genetic diseases presenting in adulthood and underscores the clinical value of incorporating exome sequencing in the evaluation and management of adults with liver disease of unknown etiology., Funding: S.V. is supported by the NIH/NIDDK (K08 DK113109 and R01 DK131033-01A1) and the Doris Duke Charitable Foundation Grant #2019081. This work was supported in part by NIH-funded Yale Liver Center, P30 DK34989., Competing Interests: Declaration of interests A.M.D., R.A.H., A.M.H., L.K., P.L., P.N., M.E.P., and L.D.W., are employees of Alnylam Pharmaceuticals. A.M.D. and L.D.W., also hold stock options in Alnylam Pharmaceuticals. M.G.S., is a principal investigator for clinical studies from Novartis, Gilead, Pliant, Cymabay, Genfit, Target PharmaSolutions. Z.G.J., consults for Olix Pharmaceuticals and receives grants from Gilead Sciences and Pfizer Pharmaceuticals. M.P.C., consults for Mallinckrodt LLC, Alexion Pharmaceuticals, and Albireo Pharma and has also received grants from Sonic Incytes. M.H.C., has received grant support from Bayer. S.V., served as consultant for Albireo Pharma. The other authors do not report any potential conflict of interest., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background: A salutary effect of treatments for Gaucher disease (GD) has been a reduction in the incidence of avascular osteonecrosis (AVN). However, there are reports of AVN in patients receiving enzyme replacement therapy (ERT) , and it is not known whether it is related to individual treatments, GBA genotypes, phenotypes, biomarkers of residual disease activity, or anti-drug antibodies. Prompted by development of AVN in several patients receiving ERT, we aimed to delineate the determinants of AVN in patients receiving ERT or eliglustat substrate reduction therapy (SRT) during 20 years in a tertiary referral center., Methods: Longitudinal follow-ups of 155 GD patients between 2001 and 2021 were analyzed for episodes of AVN on therapy, type of therapy, GBA1 genotype, spleen status, biomarkers, and other disease indicators. We applied mixed-effects logistic model to delineate the independent correlates of AVN while receiving treatment., Results: The patients received cumulative 1382 years of treatment. There were 16 episodes of AVN in 14 patients, with two episodes, each occurring in two patients. Heteroallelic p.Asn409Ser GD1 patients were 10 times (95% CI, 1.5-67.2) more likely than p.Asn409Ser homozygous patients to develop osteonecrosis during treatment. History of AVN prior to treatment initiation was associated with 4.8-fold increased risk of AVN on treatment (95% CI, 1.5-15.2). The risk of AVN among patients receiving velaglucerase ERT was 4.68 times higher compared to patients receiving imiglucerase ERT (95% CI, 1.67-13). No patient receiving eliglustat SRT suffered AVN. There was a significant correlation between GlcSph levels and AVN. Together, these biomarkers reliably predicted risk of AVN during therapy (ROC AUC 0.894, p<0.001)., Conclusions: There is a low, but significant risk of AVN in GD in the era of ERT/SRT. We found that increased risk of AVN was related to GBA genotype, history of AVN prior to treatment initiation, residual serum GlcSph level, and the type of ERT. No patient receiving SRT developed AVN. These findings exemplify a new approach to biomarker applications in a rare inborn error of metabolism to evaluate clinical outcomes in comprehensively followed patients and will aid identification of GD patients at higher risk of AVN who will benefit from closer monitoring and treatment optimization., Funding: LSD Training Fellowship from Sanofi to MB., Competing Interests: MB, MG, JR, VM, NK, GB, AA, AL No competing interests declared, LG, KK is an employee of Sanofi and may hold stocks, PM Reviewing editor, eLife, (© 2023, Basiri et al.)

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Purpose: Most patients with Gaucher disease have progressive and often disabling skeletal manifestations. We examined the long-term effect of eliglustat treatment on bone outcomes in clinical trials in adults with Gaucher disease type 1., Methods: Data from 4 completed phase 2 and 3 trials were evaluated in treatment-naïve patients or patients switching to eliglustat from enzyme replacement therapy (ERT)., Results: Overall, 319 of 393 (81%) eliglustat-treated patients remained in their trials until completion or commercial eliglustat became available. Mean eliglustat treatment duration ranged from 3.3 to 6.5 years. In treatment-naïve patients and ERT-switch patients, frequency and severity of bone pain decreased during eliglustat treatment. Mean lumbar spine T-scores shifted from abnormal to normal in treatment-naïve patients and remained in the healthy reference range or improved modestly in ERT-switch patients. Mean total bone marrow burden score shifted from marked-to-severe to moderate in treatment-naïve patients and remained moderate in ERT-switch patients. MIP-1β (marker of active bone disease) was elevated at baseline and decreased to the healthy reference range in treatment-naïve patients and remained in the healthy reference range among ERT-switch patients., Conclusion: These findings confirm the long-term efficacy of eliglustat on skeletal complications of Gaucher disease in treatment-naïve and ERT-switch patients., Competing Interests: Conflict of Interest T.M.C. was a principal investigator on the Sanofi-sponsored eliglustat ENCORE trial and has received honoraria, travel reimbursement, and grant/research support from Takeda, Shire Pharmaceuticals and Sanofi. J.C. was a principal investigator on the Sanofi-sponsored eliglustat EDGE trial; has received honoraria for consultation and advisory board participation from Sanofi, Synageva, Shire, BioMarin, National Gaucher Foundation, and Pfizer/Protalix; and has received lecture fees or honoraria for speaking at the invitation of Sanofi and SIMD North American Metabolic Academy. E.L. was a principal investigator on the Sanofi-sponsored eliglustat phase 2, ENGAGE, ENCORE, and EDGE trials and has received honoraria and travel reimbursement and participates on advisory boards of Sanofi and Shire. P.K.M. was a principal investigator on the Sanofi-sponsored eliglustat ENGAGE trial, is a member of the International Collaborative Gaucher Group (ICGG) Gaucher Registry North American Advisory Board, and has received research support, honoraria, and travel reimbursement from Sanofi. M.J.P. and M.C.F. are employees of Sanofi and own shares and/or stock options in the company., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

There are numerous reports of cancers in Gaucher disease (GD) from mostly small single-center studies; however, precise risk estimates and cancer types involved have not been delineated. We conducted a study involving 2123 patients with GD type 1 (GD1) to assess the incidence of hematological malignancies, gammopathies, and solid tumors in an international observational study, the International Cooperative Gaucher Group Gaucher Registry (Clinicaltrials.gov: NCT00358943). Risk for cancer overall and for each type of malignancy was compared to the United States (US) population using the Surveillance, Epidemiology, and End Results database. Natural history of gammopathy was determined through assessing the progression from a diagnosis of monoclonal gammopathy of unknown significance (MGUS) to multiple myeloma (MM). Risk for hematological malignancies was more than four times higher than expected compared to the general population: non-Hodgkin lymphoma was approximately three times higher; MM was approximately nine times higher. Age-specific incidence rates of MGUS were unexpectedly high among younger patients. The 10-year cumulative incidence of MM after diagnosis of MGUS was 7.9%, comparable to the general population. Compared to the general US population, GD1 patients were at higher risk for solid malignancies of liver (2.9 times), kidney (2.8 times), melanoma (2.5 times), and breast (1.4 times). Colorectal, prostate, and lung cancer risks were lower than expected. These findings help advance care of patients with GD1 by supporting recommendations for individualized monitoring for malignancies and antecedents such as MGUS for MM and provoke important questions of the role of glucosylceramide and related sphingolipids in cancer biology., (© 2022 The Authors. American Journal of Hematology published by Wiley Periodicals LLC.)

Background: Neuronopathic Gaucher disease (nGD) is a rare neurodegenerative disorder caused by biallelic mutations in GBA and buildup of glycosphingolipids in lysosomes. Neuronal injury and cell death are prominent pathological features; however, the role of GBA in individual cell types and involvement of microglia, blood-derived macrophages, and immune infiltrates in nGD pathophysiology remains enigmatic., Methods: Here, using single-cell resolution of mouse nGD brains, lipidomics, and newly generated biomarkers, we found induction of neuroinflammation pathways involving microglia, NK cells, astrocytes, and neurons., Results: Targeted rescue of Gba in microglia and neurons, respectively, in Gba -deficient, nGD mice reversed the buildup of glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph), concomitant with amelioration of neuroinflammation, reduced serum neurofilament light chain (Nf-L), and improved survival. Serum GlcSph concentration was correlated with serum Nf-L and ApoE in nGD mouse models as well as in GD patients. Gba rescue in microglia/macrophage compartment prolonged survival, which was further enhanced upon treatment with brain-permeant inhibitor of glucosylceramide synthase, effects mediated via improved glycosphingolipid homeostasis, and reversal of neuroinflammation involving activation of microglia, brain macrophages, and NK cells., Conclusions: Together, our study delineates individual cellular effects of Gba deficiency in nGD brains, highlighting the central role of neuroinflammation driven by microglia activation. Brain-permeant small-molecule inhibitor of glucosylceramide synthase reduced the accumulation of bioactive glycosphingolipids, concomitant with amelioration of neuroinflammation involving microglia, NK cells, astrocytes, and neurons. Our findings advance nGD disease biology whilst identifying compelling biomarkers of nGD to improve patient management, enrich clinical trials, and illuminate therapeutic targets., Funding: Research grant from Sanofi; other support includes R01NS110354, Yale Liver Center P30DK034989, pilot project grant., Competing Interests: CB, SN, GB, SM, JR, DK, KK, PM No competing interests declared, JG "JG is an employee of Sanofi and received stock and options as part of compensation. JG received tissues samples from Yale for data generation. The author has no other competing interests to declare", ET "ET is an employee of Sanofi. The author has no other competing interests to declare", TN T-H N was previously an employee of Sanofi. The author has no other competing interests to declare", LG LG is an employee of Sanofi and holds stocks in Sanofi. The author has no other competing interests to declare, MK MK was previously an employee of Sanofi and holds stocks in Sanofi. The author has no other competing interests to declare, HW HW was previously an employee of Sanofi. The author has no other competing interests to declare, MD HW (now retired) was previously an employee of Sanofi and holds stocks in Sanofi. The author has no other competing interests to declare, DV BZ is an employee of Sanofi. The author has no other competing interests to declare, BZ KK is an employee of Sanofi. The author has no other competing interests to declare, (© 2022, Boddupalli, Nair et al.)

Rare diseases affect > 400 million people globally with a disproportionate burden falling on children, resulting in high morbidity and mortality rates. Affected individuals in some under-resourced countries have limited access to expert care or treatments; moreover, they suffer long diagnostic journeys during which debilitating and life-threatening complications occur. Lysosomal storage disorders (LSD) are prototype rare diseases due, in the main, to inherited deficiencies of lysosomal enzymes/transporters that affect up to 1 in 5000 newborns. Recognizing the need to provide treatment access to people with LSDs everywhere, a collaborative partnership was pioneered and set up 30 years ago. Partnering with local authorities, non-government organizations across six continents, local as well as international experts, a robust, sustainable Humanitarian Program emerged that now represents the most enduring charitable access program for LSD treatment. Here we present the history, process, lasting beneficial effect of the program to develop healthcare systems and infrastructures, and the lessons learned from addressing major unmet needs for LSDs., (© 2022. The Author(s).)

Gaucher disease is reckoned for extreme phenotypic diversity that does not show consistent genotype/phenotype correlations. In Argentina, a national collaborative group, Grupo Argentino de Diagnóstico y Tratamiento de la Enfermedad de Gaucher, GADTEG, have delineated uniformly severe type 1 Gaucher disease manifestations presenting in childhood with large burden of irreversible skeletal disease. Here using Long-Read Single Molecule Real-Time (SMRT) Sequencing of GBA1 locus, we show that Rec Nci I allele is highly prevalent and associates with severe skeletal manifestations in childhood., (© 2021 Published by Elsevier Inc.)

Eliglustat, an oral substrate reduction therapy, is approved for eligible adults with Gaucher disease type 1. In the Phase 3 ENGAGE trial of previously untreated adults with Gaucher disease type 1, eliglustat-treated patients had statistically significant improvements in organ volumes and hematologic parameters compared with placebo in the 9-month primary analysis. We report final outcomes by time on eliglustat among all patients who participated in the ENGAGE trial and extension. No patient deteriorated clinically or withdrew due to adverse events; 39/40 patients entered the open-label extension period and 34/40 (85%) remained in the trial until completion or switching to commercial eliglustat after its approval (2.3-6 years). Clinically meaningful improvements in Gaucher disease manifestations were seen in all patients concomitant with reductions in pathological lipid substrate levels (glucosylceramide and glucosylsphingosine). Among patients with 4.5 years of eliglustat exposure, mean spleen volume decreased by 66% (from 17.1 to 5.8 multiples of normal [MN], n = 13), mean liver volume decreased by 23% (from 1.5 to 1.1 MN, n = 13), mean hemoglobin increased 1.4 g/dl (from 11.9 to 13.4 g/dl, n = 12), mean platelet count increased by 87% (from 67.6 to 122.6 × 10 9 /L, n = 12), median chitotriosidase decreased by 82% (from 13 394 to 2312 nmol/h/ml, n = 11), median glucosylceramide decreased by 79% (from 11.5 to 2.4 μg/ml, n = 11), median glucosylsphingosine decreased by 84% (from 518.5 to 72.1 ng/ml, n = 10), and mean spine T-score increased from -1.07 (osteopenia) to -0.53 (normal) (n = 9). The magnitude of improvement in Gaucher disease manifestations and biomarkers over time was similar among the full trial cohort. Eliglustat was well-tolerated and led to clinically significant improvements in previously untreated patients with Gaucher disease type 1 during 4.5 years of treatment., (© 2021 The Authors. American Journal of Hematology published by Wiley Periodicals LLC.)

In Gaucher disease (GD), genetic deficiency of acid β-glucosidase leads to accumulation of its substrate glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph). Lipid-laden cells, most prominently seen as macrophages engorged with GlcCer and GlcSph-laden lysosomes, trigger chronic metabolic inflammation and multisystemic phenotypes. Among the pleiotropic effects of inflammatory cascades, the induction of glucosylceramide synthase accentuates the primary metabolic defect. First-line therapies for adults with GD type 1 include Enzyme Replacement Therapy (ERT) and eliglustat Substrate Reduction Therapy (SRT). The ENCORE phase 3 clinical trial of eliglustat demonstrated non-inferiority compared to ERT. It is not known whether switching stable patients from long-term ERT to SRT results in the incremental reversal of the disease phenotype and its surrogate indicators. Herein, we report real-world experience from a single tertiary referral center of 38 adult GD type 1 patients, stable on long-term ERT (mean 13.3 years), who switched to eliglustat SRT (mean 3.1 years). After switch to SRT, there was significant reduction in spleen volume ( P  = 0.003) while liver volume, which was normal at baseline, remained unchanged. Platelet counts increased significantly ( P  = 0.026). Concomitantly, there was reduction of three validated biomarkers of Gaucher disease activity: plasma GlcSph decreased from 63.7 ng/ml (95% CI, 37.6-89.8) to 26.1 ng/ml (95% CI, 15.7-36.6) ( P  < 0.0001); chitotriosidase fell from 1136.6 nmol/ml/h (95% CI, 144.7-2128.6) to 466.9 nmol/ml/h (95% CI, 209.9-723.9) ( P  = 0.002); and glycoprotein non-metastatic melanoma B (gpNMB) decreased from 59.3 ng/ml (95% CI, 39.7-78.9) to 43.6 ng/ml (95% CI, 30.7-56.6) ( P  = 0.0006). There were no episodes of avascular necrosis or fractures in patients on SRT. Patients reported favorable experiences of switching from alternate week infusions to oral therapy. Collectively, these results demonstrate that the switch to eliglustat SRT from ERT leads to incremental response, even in stable patients after long-term ERT., (© 2021 The Author(s).)

Objective: We evaluated whether substrate reduction therapy with miglustat could alter the course of action myoclonus-renal failure syndrome (AMRF), a rare, progressive myoclonic epilepsy with early mortality caused by scavenger receptor class B member 2 (S CARB2 ) gene mutations., Methods: We identified an AMRF patient with a biallelic combination of SCARB2 mutations determined by whole exome sequencing. SCARB2 encodes a protein that traffics β-glucocerebrosidase to the lysosomal membrane. Mutations lead to a complex pattern of glucosylceramide accumulation and neurologic symptoms including progressive action myoclonus, seizures, and ataxia. We then evaluated the effect of inhibiting glucosylceramide synthesis, as is used in Gaucher disease. The patient was treated for 3 years with miglustat after several years of steady worsening., Results: Progression of myoclonus halted, dysphagia resolved, some skills were reacquired, and seizures remained well controlled., Conclusions: The response suggests that neurologic symptoms of SCARB2 -associated AMRF could be ameliorated, at least partly, by targeting glycosphingolipid metabolism with available medications., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest.

Chitotriosidase activity and CCL18 concentration are interchangeably used for monitoring Gaucher disease (GD) activity, together with clinical assessment. However, comparative studies of these two biomarkers are scarce and of limited sample size. The aim of this systematic review with meta-analysis of individual participant data (IPD) was to compare the accuracy of chitotriosidase activity and CCL18 concentration for assessing type I GD severity. We identified cross-sectional and prospective cohort studies by searching Medline, EMBASE, and CENTRAL from 1995 to June 2017, and by contacting research groups. The primary outcome was a composite of liver volume >1.25 multiple of normal (MN), spleen volume >5 MN, hemoglobin concentration <11 g/dL, and platelet count <100x109/L. Overall, IPD included 1109 observations from 334 patients enrolled in nine primary studies, after excluding 111 patients with undocumented values and 18 patients with deficient chitotriosidase activity. IPD were unavailable for 14 eligible primary studies. The primary outcome was associated with a 5.3-fold (95% confidence interval [CI], 4.2 to 6.6) and 3.0-fold (95% CI, 2.6 to 3.6) increase of the geometric mean for chitotriosidase activity and CCL18 concentration, respectively. The corresponding areas under the receiver operating characteristics curves were 0.82 and 0.84 (summary difference, 0.02, 95% CI, -0.02 to 0.05). The addition of chitotriosidase activity did not improve the accuracy of CCL18 concentration. Estimates remained robust in the sensitivity analysis and consistent across subgroups. Neither chitotriosidase activity nor CCL18 concentration varied significantly according to a recent history of bone events among 97 patients. In conclusion, CCL18 concentration is as accurate as chitotriosidase activity in assessing hematological and visceral parameters of GD severity and can be measured in all GD patients. This meta-analysis supports the use of CCL18 rather than chitotriosidase activity for monitoring GD activity in routine practice.

SARS-CoV-2 infection carries high morbidity and mortality in individuals with chronic disorders. Its impact in rare disease populations such as Gaucher disease (GD) is unknown. In GD, decreased acid β-glucosidase activity leads to the accumulation of inflammatory glycosphingolipids and chronic myeloid cell immune activation which a priori could predispose to the most severe effects of SARS-CoV-2. To evaluate the determinants of SARS-CoV-2 infection in GD, we conducted a cross-sectional study in a large cohort. 181 patients were enrolled, including 150 adults and 31 children, with a majority of patients on treatment (78%). Information on COVID-19 exposure, symptoms, and SARS-CoV-2 nucleic acid and/or antibody testing was obtained during the peak of the pandemic in the New York City metropolitan area. Forty-five adults reported a primary exposure to someone with COVID-19 and 17 (38%) of these patients reported at least one COVID-19 symptom. A subset of adults was tested (n = 88) and in this group 18% (16/88) were positive. Patients testing positive for SARS-CoV-2 had significantly more symptoms (4.4 vs 0.3, p < 0.001) than patients testing negative. Among patients who were antibody-positive, quantitative titers indicated moderate to high antibody response. In GD adults, male gender, older age, increased BMI, comorbidities, GBA genotype, prior splenectomy and treatment status were not associated with the probability of reporting symptoms or testing positive. No patient required COVID-19-specific treatments and there were no deaths. Our data suggests that GD does not confer a heightened risk for severe effects of SARS-CoV-2 infection feared based on the known chronic inflammatory state in these patients., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Acid sphingomyelinase deficiency (ASMD) also known as Niemann-Pick disease, is a rare lysosomal storage disorder with a diverse disease spectrum that includes slowly progressive, chronic visceral (type B) and neurovisceral forms (intermediate type A/B), in addition to infantile, rapidly progressive fatal neurovisceral disease (type A)., Purpose and Methods: We review the published evidence on the relevance of splenomegaly and reduced lung diffusion capacity to the clinical burden of chronic forms of ASMD. Targeted literature searches were conducted to identify relevant ASMD and non-ASMD studies for associations between diffusing capacity of the lungs for carbon monoxide (DL CO ) and splenomegaly, with clinical parameters and outcome measures., Results: Respiratory disease and organomegaly are primary and independent contributors to mortality, disease burden, and morbidity for patients with chronic ASMD. The degree of splenomegaly correlates with short stature, atherogenic lipid profile, and degree of abnormality of hematologic parameters, and thus may be considered a surrogate marker for bleeding risk, abnormal lipid profiles and possibly, liver fibrosis. Progressive lung disease is a prevalent clinical feature of chronic ASMD, contributing to a decreased quality of life (QoL) and an increased disease burden. In addition, respiratory-related complications are a major cause of mortality in ASMD., Conclusions: The reviewed evidence from ASMD natural history and observational studies supports the use of lung function and spleen volume as clinically meaningful endpoints in ASMD trials that translate into important measures of disease burden for patients., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Eliglustat is a first-line oral therapy for adults with Gaucher disease type 1 (GD1) with extensive, intermediate, or poor CYP2D6-metabolizer phenotypes (90% of patients). We report real-world outcomes after 2 years of eliglustat therapy in the International Collaborative Gaucher Group Gaucher Registry (NCT00358943). As of January 2019, baseline and 2-year data (±1 year) were available for 231 eliglustat-treated GD1 patients: 19 treatment-naïve (zero splenectomized) and 212 ERT patients who switched to eliglustat (36 splenectomized). Most patients (89%) were from the United States, where eliglustat was first approved. In treatment-naïve patients, mean hemoglobin increased from 12.4 to 13.4 g/dL (P = .004, n = 18), mean platelet count increased from 113 to 156 × 10 9 /L (P < .001, n = 17); mean spleen volume decreased from 7.4 to 3.5 multiples of normal (MN) (P = .02, n = 7); mean liver volume remained normal (n = 7), and median spine Z-score was unchanged (-1.3 to -1.2, n = 6). In non-splenectomized switch patients, mean hemoglobin remained stable/non-anemic (n = 167); mean platelet count remained stable/normal (n = 165); mean spleen volume decreased from 3.3 to 2.8 MN (P < .001, n = 64); mean liver volume remained normal (n = 63), and median lumbar spine Z-score improved from -0.7 to -0.4 (P = .014, n = 68). In splenectomized switch patients, mean hemoglobin remained stable/non-anemic (n = 31); mean platelet count increased from 297 to 324 × 10 9 /L (non-significant, n = 29); mean liver volume remained normal (n = 13); median spine Z-score improved from -0.8 to -0.6 (non-significant, n = 11). Median chitotriosidase decreased in all groups (P < .01 for all). These real-world results are consistent with eliglustat clinical trial results demonstrating long-term benefit in treatment-naïve patients and stability in ERT switch patients., (© 2020 The Authors. American Journal of Hematology published by Wiley Periodicals LLC.)

In Gaucher disease type 1 (GD1), genetic deficiency of lysosomal glucocerebrosidase results in the accumulation of glucosylceramide and glucosylsphingosine (GlcSph), that underlie chronic lipid-mediated metabolic inflammation. An important age-related phenotype is high risk of monoclonal gammopathy (MG), including multiple myeloma. We identified GlcSph, a pathological lyso-sphingolipid exclusively elevated in GD, as a mediator of B cell activation and as an antigenic target for GD1-associated MG. Saposin C (SapC), is a lipid-binding protein and activator of lysosomal glucocerebrosidase, which when mutated, cause a rare variant of GD. Sera of GD1 patients with MG of diverse immunoglobulin types were compared to GD patients without gammopathy for reactivity against GlcSph and SapC. We show reactivity of clonal immunoglobulin in GD1 to GlcSph but not to SapC. In two patients with GD1 and gammopathy, GlcSph-reduction therapy with eliglustat resulted in reduction in clonal Ig. Together, our data show that GlcSph but not SapC is the antigenic target in GD1-associated MG and that therapy aimed at reducing the levels of immunogenic lipid resulted in reduction of clonal immunoglobulin in vivo., Competing Interests: Declaration of Competing Interest Dr. Pramod Mistry has received lecture fees and travel support and served as consultant for Sanofi Genzyme., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The etiology and incidence of cirrhosis in adults has been well studied, however there is scant data in younger patients. The aim of this study was to determine causes of cirrhosis in patients ≤40 years old. In this multi-institutional retrospective study, pathology databases were searched for patients ≤40-year-old with a diagnosis of cirrhosis from 1995 to 2018. Clinical charts and pathology reports were reviewed to identify etiologies of cirrhosis in each case. The patients were divided into 4 age groups (<1, 1- < 5, 5- < 18, and 18-40 years old) for further analysis. We identified 594 patients (264 female, 330 male). Among <18-year-old patients, congenital cholestatic diseases and developmental disorders were the most common causes of cirrhosis (50.2%, 172/342). Metabolic and genetic diseases were also seen more commonly in this age group (16.6%, 57/342). In contrast, viral hepatitides were the most common cause of cirrhosis in 18-40-year-old patients (39.6%, 100/252) followed by autoimmune and fatty liver disease (22.2%, 56/252 and 15.07%, 38/252, respectively). Cryptogenic cirrhosis (overall 7.2%, 42/594) was seen in 3% (4/133), 1.4% (1/69), 10.7% (15/140) and 8.7% (22/252) of patients aged <1, 1- < 5, 5- < 18, and 18-40 years, respectively. Developmental and metabolic disorders are the most common causes of cirrhosis in children (<18), while viral hepatitides are leading causes in adolescents and young adults (18-40) similar to adults. The incidence of cryptogenic cirrhosis also varies depending on the age, being lowest in 1- < 5 year and highest in 5- < 18 year age group children., (Copyright © 2019. Published by Elsevier Inc.)

The clinical relevance of the Human Genome Project and next-generation sequencing technology was demonstrated for the first time in 2009, when whole-exome sequencing (WES) provided the definitive diagnosis of congenital chloride diarrhea in an infant with presumed renal salt-wasting disease. Over the past decade, numerous studies have shown the utility of WES for clinical diagnosis as well as for discovery of novel genetic disorders through analysis of a single or a handful of informative pedigrees. Hence, advances in improving the speed, accuracy, and computational analysis combined with exponential decrease in the cost of sequencing the human genome is transforming the practice of medicine. The impact of WES has been most noticeable in pediatric disorders and oncology, but its utility in the liver clinic is recently emerging. Here, we assess the current status of WES for clinical diagnosis and acceleration of translation research to enhance care of patients with liver disease., (© 2019 by the American Association for the Study of Liver Diseases.)

In Gaucher disease, several macrophage-specific biomarkers have been validated for use in the clinic. However, Gaucher disease is more complex involving system-wide pathophysiology beyond the macrophage, and based on gene array analysis in our Gaucher disease mouse model and other emerging pathophysiologic insights, we evaluated serum levels of cathepsins D and S, YKL-40 and progranulin in Gaucher disease patients. We assessed their biomarker potential in Gaucher disease and compared them to established Gaucher disease biomarkers, chitotriosidase, chemokine ligand 18 (CCL18), and other indicators of disease severity and response to therapy. Mean YKL-40 and cathepsin D and S levels were significantly higher in Gaucher disease patients compared to healthy controls; in contrast, mean progranulin levels were lower in Gaucher disease patients compared to healthy controls. Enzyme replacement therapy resulted in a significant reversal of elevated cathepsin D and S but there was no change in progranulin and YKL-40 levels. Patients with persistent splenomegaly after long-term enzyme replacement therapy had significantly higher serum YKL-40 than patients with smaller spleens (63.0 ± 6.4 ng/ml vs. 46.4 ± 4.3 ng/ml, p = .03). Serum YKL-40 levels were higher in subjects with severe bone involvement (Hermann Score 3 to 5) compared to those with milder bone involvement (Hermann Score 1 to 2) (70.1 ± 4.3 ng/ml vs. 48.1 ± 3.7 ng/ml, p = .0002). YKL-40 was only weakly associated with chitotriosidase (r = 0.2, p = .008) and CCL18 (r = 0.3, p = .0004), and cathepsin S was moderately associated with chitotriosidase (r = 0.4, p = .01) and CCL18 (r = 0.6, p < .0001). Receiver operating curves for progranulin and YKL-40 demonstrated areas under the curves of 0.80 and 0.70, respectively. In conclusion, while these biomarkers do not meet robust properties of established macrophage-specific biomarkers, they may inform severity of skeletal disease, contribution of fibrosis to residual splenomegaly, and other disease manifestations. These findings, including markedly low progranulin levels that do not change upon enzyme replacement therapy, are intriguing to prompt further investigations to decipher their role in pathophysiology and relevance to diverse phenotypes of Gaucher disease., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background & Aims: Adult patients suffering from liver disease of unknown cause represent an understudied and underserved population. The use of whole-exome sequencing (WES) for the assessment of a broader spectrum of non-oncological diseases, among adults, remains poorly studied. We assessed the utility of WES in the diagnosis and management of adults with unexplained liver disease despite comprehensive evaluation by a hepatologist and with no history of alcohol overuse., Methods: We performed WES and deep phenotyping of 19 unrelated adult patients with idiopathic liver disease recruited at a tertiary academic health care center in the US., Results: Analysis of the exome in 19 cases identified 4 monogenic disorders in 5 unrelated adults. Patient 1 suffered for 18 years from devastating complications of undiagnosed type 3 familial partial lipodystrophy due to a deleterious heterozygous variant in PPARG. Molecular diagnosis enabled initiation of leptin replacement therapy with subsequent normalization of liver aminotransferases, amelioration of dyslipidemia, and decreases in daily insulin requirements. Patients 2 and 3 were diagnosed with MDR3 deficiency due to recessive mutations in ABCB4. Patient 4 with a prior diagnosis of non-alcoholic steatohepatitis was found to harbor a mitochondrial disorder due to a homozygous pathogenic variant in NDUFB3; this finding enabled initiation of disease preventive measures including supplementation with antioxidants. Patient 5 is a lean patient with hepatic steatosis of unknown etiology who was found to have a damaging heterozygous variant in APOB., Conclusions: Genomic analysis yielded an actionable diagnosis in a substantial number (∼25%) of selected adult patients with chronic liver disease of unknown etiology. This study supports the use of WES in the evaluation and management of adults with idiopathic liver disease in clinical practice., Lay Summary: We performed whole-exome sequencing in 19 adult patients with unexplained liver disease after an unrevealing conventional work-up performed by a hepatologist. In 5 cases, genomic analysis led to a diagnosis and informed treatment and management of the disease. Therefore, we suggest using whole-exome sequencing in the evaluation and management of adults with unexplained liver disease., (Copyright © 2019 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.)

Background: Acid sphingomyelinase deficiency (ASMD), a rare lysosomal storage disease, results from mutations in SMPD1, the gene encoding acid sphingomyelinase (ASM). As a result, sphingomyelin accumulates in multiple organs including spleen, liver, lung, bone marrow, lymph nodes, and in the most severe form, in the CNS and peripheral nerves. Clinical manifestations range from rapidly progressive and fatal infantile neurovisceral disease, to less rapidly progressing chronic neurovisceral and visceral forms that are associated with significant morbidity and shorter life span due to respiratory or liver disease., Objectives: To provide a contemporary guide of clinical assessments for disease monitoring and symptom management across the spectrum of ASMD phenotypes., Methods: An international group of ASMD experts in various research and clinical fields used an evidence-informed consensus process to identify optimal assessments, interventions, and lifestyle modifications., Results: Clinical assessment strategies for major organ system involvement, including liver, spleen, cardiovascular, pulmonary, and neurological/developmental are described, as well as symptomatic treatments, interventions, and/or life style modifications that may lessen disease impact., Conclusions: There is currently no disease-specific treatment for ASMD, although enzyme replacement therapy with a recombinant human ASM (olipudase alfa) is in clinical development. Current monitoring addresses symptoms and multisystem involvement. Recommended interventions and lifestyle modifications are designed to address morbidity and disease complications and improve patient quality of life. While infantile neurovisceral ASMD is uniformly fatal in early childhood, patients with chronic visceral and chronic neurovisceral ASMD require appropriate management throughout childhood and adulthood by an interdisciplinary clinical team., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Gaucher disease (GD) is associated with an increased risk for malignancies. Next to hematological malignancies, the development of solid tumors in several organs has been described. The liver is one of the major storage sites involved in GD pathogenesis, and is also affected by liver-specific complications. In this case series, we describe 16 GD type 1 (GD1) patients from eight different referral centers around the world who developed hepatocellular carcinoma (HCC). Potential factors contributing to the increased HCC risk in GD patients are studied. Eleven patients had undergone a splenectomy in the past. Liver cirrhosis, one of the main risk factors for the development of HCC, was present in nine out of 14 patients for whom data was available. Three out of seven examined patients showed a transferrin saturation > 45%. In these three patients the presence of iron overload after histopathological examination of the liver was shown. Chronic hepatitis C infection was present in three of 14 examined cases. We summarized all findings and made a comparison to the literature. We recommend that GD patients, especially those with prior splenectomy or iron overload, be evaluated for signs of liver fibrosis and if found to be monitored for HCC development.

A role for antigen-driven stimulation has been proposed in the pathogenesis of monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) based largely on the binding properties of monoclonal Ig. However, insights into antigen binding to clonal B cell receptors and in vivo responsiveness of the malignant clone to antigen-mediated stimulation are needed to understand the role of antigenic stimulation in tumor growth. Lysolipid-reactive clonal Ig were detected in Gaucher disease (GD) and some sporadic gammopathies. Here, we show that recombinant Ig (rIg) cloned from sort-purified single tumor cells from lipid-reactive sporadic and GD-associated gammopathy specifically bound lysolipids. Liposome sedimentation and binding assays confirmed specific interaction of lipid-reactive monoclonal Ig with lysolipids. The clonal nature of lysolipid-binding Ig was validated by protein sequencing. Gene expression profiling and cytogenetic analyses from 2 patient cohorts showed enrichment of nonhyperdiploid tumors in lipid-reactive patients. In vivo antigen-mediated stimulation led to an increase in clonal Ig and plasma cells (PCs) in GD gammopathy and also reactivated previously suppressed antigenically related nonclonal PCs. These data support a model wherein antigenic stimulation mediates an initial polyclonal phase, followed by evolution of monoclonal tumors enriched in nonhyperdiploid genomes, responsive to underlying antigen. Targeting underlying antigens may therefore prevent clinical MM.

Justification: Gaucher disease (GD) is amongst the most frequently occurring lysosomal storage disorder in all ethnicities. The clinical manifestations and natural history of GD is highly heterogeneous with extreme geographic and ethnic variations. The literature on GD has paucity of information and optimal management guidelines for Indian patients., Process: Gaucher Disease Task Force was formed under the auspices of the Society for Indian Academy of Medical Genetics. Invited experts from various specialties formulated guidelines for the management of patients with GD. A writing committee was formed and the draft guidelines were circulated by email to all members for comments and inputs. The guidelines were finalized in December 2016 at the annual meeting of the Indian Academy of Medical Genetics., Objectives: These guidelines are intended to serve as a standard framework for treating physicians and the health care systems for optimal management of Gaucher disease in India and to define unique needs of this patient population., Recommendations: Manifestations of GD are protean and a high index of suspicion is essential for timely diagnosis. Patients frequently experience diagnostic delays during which severe irreversible complications occur. Leucocyte acid b-glucosidase activity is mandatory for establishing the diagnosis of Gaucher disease; molecular testing can help identify patients at risk of neuronopathic disease. Enzyme replacement therapy for type 1 and type 3 Gaucher disease is the standard of care. Best outcomes are achieved by early initiation of therapy before onset of irreversible complications. However, in setting of progressive neurological symptoms such as seizures and or/ neuroregression, ERT is not recommended, as it cannot cross the blood brain barrier. The recommendations herein are for diagnosis, for initiation of therapy, therapeutic goals, monitoring and follow up of patients. We highlight that prevention of recurrence of the disease through genetic counseling and prenatal diagnosis is essential in India, due to uniformly severe phenotypes encountered in our population.

In the spleens of Gaucher disease mice and patients, there is a striking elevation of expression of glycoprotein non-Metastatic Melanoma B (gpNMB). We conducted a study in a large cohort of patients with Gaucher disease to assess the utility of serum levels of soluble fragment of gpNMB as a biomarker of disease activity. There was >15-fold elevation of gpNMB in sera of untreated patients with Gaucher disease. gpNMB levels correlated with overall disease severity as well as the severity of individual organ compartments: liver, spleen, bone and hematological disease. Imiglucerase enzyme replacement therapy resulted in significant reduction of gpNMB. Serum levels of gpNMB were highly correlated with accumulation of bioactive lipid substrate of Gaucher disease, glucosylsphingosine as well as established biomarkers, chitotriosidase and chemokine, CCL18. Our results suggest utility of gpNMB as a biomarker of Gaucher disease to monitor individual patients and cohorts of patients for disease progression or response to therapy. Investigation of gpNMB in Gaucher disease pathophysiology is likely to illuminate our understanding disease mechanisms., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Eliglustat, an oral substrate reduction therapy, is a first-line treatment for adults with Gaucher disease type 1 (GD1) who are poor, intermediate, or extensive CYP2D6 metabolizers (>90% of patients). In the primary analysis of the Phase 3 ENGAGE trial (NCT00891202), eliglustat treatment for 9 months resulted in significant reductions in spleen and liver volumes and increases in hemoglobin concentration and platelet count compared with placebo. We report 18-month outcomes of patients who entered the trial extension period, in which all patients received eliglustat. Of 40 trial patients, 39 entered the extension period, and 38 completed 18 months. Absolute values and percent change over time were determined for spleen and liver volume, hemoglobin concentration, platelet count, bone mineral density, bone marrow burden, and Gaucher disease biomarkers. For patients randomized to eliglustat in the double-blind period, continuing treatment with eliglustat for 9 more months resulted in incremental improvement of all disease parameters. For patients randomized to placebo in the double-blind period, eliglustat treatment during the 9-month, open-label period resulted in significant decrease of spleen and liver volumes and significant increase of hemoglobin and platelets, with a similar rate of change to patients who had received eliglustat in the double-blind period. Eliglustat treatment was also associated with improvement in bone marrow burden score, bone mineral density, and established biomarkers of Gaucher disease, including reduction of the bioactive lipid, glucosylsphingosine. These findings underscore the efficacy of eliglustat in treatment-naïve patients. Eliglustat was well-tolerated, and there were no new safety concerns with longer-term exposure., (© 2017 The Authors American Journal of Hematology Published by Wiley Periodicals, Inc.)

Glucocerebrosidase 1 ( GBA ) mutations responsible for Gaucher disease (GD) are the most common genetic risk factor for Parkinson's disease (PD). Although the genetic link between GD and PD is well established, the underlying molecular mechanism(s) are not well understood. We propose that glucosylsphingosine, a sphingolipid accumulating in GD, mediates PD pathology in GBA -associated PD. We show that, whereas GD-related sphingolipids (glucosylceramide, glucosylsphingosine, sphingosine, sphingosine-1-phosphate) promote α-synuclein aggregation in vitro , glucosylsphingosine triggers the formation of oligomeric α-synuclein species capable of templating in human cells and neurons. Using newly generated GD/PD mouse lines of either sex [ Gba mutant (N370S, L444P, KO) crossed to α-synuclein transgenics], we show that Gba mutations predispose to PD through a loss-of-function mechanism. We further demonstrate that glucosylsphingosine specifically accumulates in young GD/PD mouse brain. With age, brains exhibit glucosylceramide accumulations colocalized with α-synuclein pathology. These findings indicate that glucosylsphingosine promotes pathological aggregation of α-synuclein, increasing PD risk in GD patients and carriers. SIGNIFICANCE STATEMENT Parkinson's disease (PD) is a prevalent neurodegenerative disorder in the aging population. Glucocerebrosidase 1 mutations, which cause Gaucher disease, are the most common genetic risk factor for PD, underscoring the importance of delineating the mechanisms underlying mutant GBA -associated PD. We show that lipids accumulating in Gaucher disease, especially glucosylsphingosine, play a key role in PD pathology in the brain. These data indicate that ASAH1 (acid ceramidase 1) and GBA2 (glucocerebrosidase 2) enzymes that mediate glucosylsphingosine production and metabolism are attractive therapeutic targets for treating mutant GBA -associated PD., (Copyright © 2017 the authors 0270-6474/17/379617-15$15.00/0.)

Disclaimer:This diagnostic guideline is intended as an educational resource and represents the opinions of the authors, and is not representative of recommendations or policy of the American College of Medical Genetics and Genomics (ACMG). The information should be considered a consensus based on expert opinion, as more comprehensive levels of evidence were not available in the literature in all cases., Background: Acid sphingomyelinase deficiency (ASMD) is a rare, progressive, and often fatal lysosomal storage disease. The underlying metabolic defect is deficiency of the enzyme acid sphingomyelinase that results in progressive accumulation of sphingomyelin in target tissues. ASMD manifests as a spectrum of severity ranging from rapidly progressive severe neurovisceral disease that is uniformly fatal to more slowly progressive chronic neurovisceral and chronic visceral forms. Disease management is aimed at symptom control and regular assessments for multisystem involvement., Purpose and Methods: An international panel of experts in the clinical and laboratory evaluation, diagnosis, treatment/management, and genetic aspects of ASMD convened to review the evidence base and share personal experience in order to develop a guideline for diagnosis of the various ASMD phenotypes., Conclusions: Although care of ASMD patients is typically provided by metabolic disease specialists, the guideline is directed at a wide range of providers because it is important for primary care providers (e.g., pediatricians and internists) and specialists (e.g., pulmonologists, hepatologists, and hematologists) to be able to identify ASMD.Genet Med advance online publication 13 April 2017.

This study tests the hypothesis that the prevalence of severe clinical manifestations in Gaucher disease type 1 (GD1) patients at the time of treatment initiation has changed since alglucerase/imiglucerase enzyme replacement therapy (ERT) was approved in the United States (US) in 1991. US alglucerase/imiglucerase-treated GD1 patients from the International Collaborative Gaucher Group Gaucher Registry clinicaltrials.gov NCT00358943 were stratified by age at ERT initiation (<18, 18 to <50, ≥50 years), era of ERT initiation (1991-1995, 1996-2000, 2001-2005, 2006-2009), and splenectomy status pre-ERT. Prevalence of splenectomy decreased dramatically across the eras among all age groups. Bone manifestations were more prevalent in splenectomized patients than non-splenectomized patients in all age groups. Prevalence of bone manifestations differed across eras in certain age groups: non-splenectomized patients had a lower prevalence of ischemic bone events (pediatric patients) and bone crisis (pediatric patients and adults 18 to <50 years) in later eras; splenectomized adult (18 to <50 years) patients had a lower prevalence of ischemic bone events and bone crisis in later eras. Over two decades after the introduction of ERT, the prevalence of splenectomy and associated skeletal complications has declined dramatically. Concomitantly, the interval between diagnosis and initiation of ERT has decreased, most strikingly in pediatric patients who have the most severe disease. Together, these findings suggest that since the introduction of alglucerase/imiglucerase ERT, optimal standard of care has become established in the US to prevent destructive complications of GD1., (© 2017 The Authors American Journal of Hematology Published by Wiley Periodicals, Inc.)

Background: Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by deficiency in acid beta-glucosidase. GD exhibits a wide clinical spectrum of disease severity with an unpredictable natural course. Plasma chitotriosidase activity and CC chemokine ligand 18 (CCL18) have been exchangeably used for monitoring GD activity and response to enzyme replacement therapy in conjunction with clinical assessment. Yet, a large-scale head-to-head comparison of these two biomarkers is currently lacking. We propose a collaborative systematic review with meta-analysis of individual participant data (IPD) to compare the accuracy of plasma chitotriosidase activity and CCL18 in assessing type I (i.e., non-neuropathic) GD severity., Methods: Eligible studies include cross-sectional, cohort, and randomized controlled studies recording both plasma chitotriosidase activity and CCL18 level at baseline and/or at follow-up in consecutive children or adult patients with type I GD. Pre-specified surrogate outcomes reflecting GD activity include liver and spleen volume, hemoglobin concentration, platelet count, and symptomatic bone events with imaging confirmation. Primary studies will be identified by searching Medline (1995 onwards), EMBASE (1995 onwards), and Cochrane Central Register of Controlled Trials (CENTRAL). Electronic search will be complemented by contacting research groups in order to identify unpublished relevant studies. Where possible, IPD will be extracted from published articles. Corresponding authors will be invited to collaborate by supplying IPD. The methodological quality of retrieved studies will be appraised for each study outcome, using a checklist adapted from the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The primary outcome will be a composite of liver volume >1.25 multiple of normal (MN), spleen volume >5 MN, hemoglobin concentration <11 g/dL, or platelet count <100 × 10 9 /L. Effect size estimates for biomarker comparative accuracy in predicting outcomes will be reported as differences in areas under receiver operating characteristic curves along with 95% confidence intervals. Effect size estimates will be reported as (weighted) mean differences along with 95% confidence intervals for each biomarker according to outcomes. IPD meta-analysis will be conducted with both one- and two-stage approaches., Discussion: Valid and precise accuracy estimates will be derived for CCL18 relative to plasma chitotriosidase activity in discriminating patients according to GD severity., Systematic Review Registration: PROSPERO 2015 CRD42015027243.

In Gaucher disease (GD), deficiency of lysosomal acid β-glucosidase results in a broad phenotypic spectrum that is classified into three types based on the absence (type 1 [GD1]) or presence and severity of primary central nervous system involvement (type 2 [GD2], the fulminant neuronopathic form, and type 3 [GD3], the milder chronic neuronopathic form). Enzyme replacement therapy (ERT) with imiglucerase ameliorates and prevents hematological and visceral manifestations in GD1, but data in GD3 are limited to small, single-center series. The effects of imiglucerase ERT on hematological, visceral and growth outcomes (note: ERT is not expected to directly impact neurologic outcomes) were evaluated during the first 5years of treatment in 253 children and adolescents (<18years of age) with GD3 enrolled in the International Collaborative Gaucher Group (ICGG) Gaucher Registry. The vast majority of GBA mutations in this diverse global population consisted of only 2 mutations: L444P (77%) and D409H (7%). At baseline, GD3 patients exhibited early onset of severe hematological and visceral disease and growth failure. During the first year of imiglucerase treatment, hemoglobin levels and platelet counts increased and liver and spleen volumes decreased, leading to marked decreases in the number of patients with moderate or severe anemia, thrombocytopenia, and hepatosplenomegaly. These improvements were maintained through Year 5. There was also acceleration in linear growth as evidenced by increasing height Z-scores. Despite devastating disease at baseline, the probability of surviving for at least 5years after starting imiglucerase was 92%. In this large, multinational cohort of pediatric GD3 patients, imiglucerase ERT provided a life-saving and life-prolonging benefit for patients with GD3, suggesting that, with proper treatment, many such severely affected patients can lead productive lives and contribute to society., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

High consanguinity rates, poor access to accurate diagnostic tests, and costly therapies are the main causes of increased burden of lysosomal storage disorders (LSDs) in developing countries. Therefore, there is a major unmet need for accurate and economical diagnostic tests to facilitate diagnosis and consideration of therapies before irreversible complications occur. In cross-country study, we utilized dried blood spots (DBS) of 1,033 patients clinically suspected to harbor LSDs for enzymatic diagnosis using modified fluorometric assays from March 2013 through May 2015. Results were validated by demonstrating reproducibility, testing in different sample types (leukocytes/plasma/skin fibroblast), mutation study, or measuring specific biomarkers. Thirty percent (307/1,033) were confirmed to have one of the LSDs tested. Reference intervals established unambiguously identified affected patients. Correlation of DBS results with other biological samples (n = 172) and mutation studies (n = 74) demonstrated 100% concordance in Gaucher, Fabry, Tay Sachs, Sandhoff, Niemann-Pick, GM1, Neuronal ceroid lipofuscinosis (NCL), Fucosidosis, Mannosidosis, Mucopolysaccharidosis (MPS) II, IIIb, IVa, VI, VII, and I-Cell diseases, and 91.4% and 88% concordance in Pompe and MPS-I, respectively. Gaucher and Pompe are the most common LSDs in India and Pakistan, followed by MPS-I in both India and Sri Lanka. Study demonstrates utility of DBS for reliable diagnosis of LSDs. Diagnostic accuracy (97.6%) confirms veracity of enzyme assays. Adoption of DBS will overcome significant hurdles in blood sample transportation from remote regions. DBS enzymatic and molecular diagnosis should become the standard of care for LSDs to make timely diagnosis, develop personalized treatment/monitoring plan, and facilitate genetic counseling.