Clinical and genetic characteristics of Korean patients with Gaucher disease

Biobank-scale characterization of Alzheimer's disease and related dementias identifies potential disease-causing variants, risk factors, and genetic modifiers across diverse ancestries

Alzheimer's disease and related dementias (AD/ADRDs) pose a significant global public health challenge, underscored by the intricate interplay of genetic and environmental factors that differ across ancestries. To effectively implement equitable, personalized therapeutic interventions on a global scale, it is essential to identify disease-causing mutations and genetic risk and resilience factors across diverse ancestral backgrounds. Exploring genetic-phenotypic correlations across the globe enhances the generalizability of research findings, contributing to a more inclusive and universal understanding of disease. This study leveraged biobank-scale data to conduct the largest multi-ancestry whole-genome sequencing characterization of AD/ADRDs. We aimed to build a valuable catalog of potential disease-causing, genetic risk and resilience variants impacting the etiology of these conditions. We thoroughly characterized genetic variants from key genes associated with AD/ADRDs across 11 genetic ancestries, utilizing data from All of Us, UK Biobank, 100,000 Genomes Project, Alzheimer's Disease Sequencing Project, and the Accelerating Medicines Partnership in Parkinson's Disease, including a total of 25,001 cases and 93,542 controls. We prioritized 116 variants possibly linked to disease, including 18 known pathogenic and 98 novel variants. We detected previously described disease-causing variants among controls, leading us to question their pathogenicity. Notably, we showed a higher frequency of APOE ε4/ε4 carriers among individuals of African and African Admixed ancestry compared to other ancestries, confirming ancestry-driven modulation of APOE-associated AD/ADRDs. A thorough assessment of APOE revealed a disease-modifying effect conferred by the TOMM40:rs11556505, APOE:rs449647, 19q13.31:rs10423769, NOCT:rs13116075, CASS4:rs6024870, and LRRC37A:rs2732703 variants among APOE ε4 carriers across different ancestries. In summary, we compiled the most extensive catalog of established and novel genetic variants in known genes increasing risk or conferring resistance to AD/ADRDs across diverse ancestries, providing clinical insights into their genetic-phenotypic correlations. The findings from this investigation hold significant implications for potential clinical trials and therapeutic interventions on a global scale. Finally, we present an accessible and user-friendly platform for the AD/ADRDs research community to help inform and support basic, translational, and clinical research on these debilitating conditions (https://niacard.shinyapps.io/MAMBARD_browser/).

Neuronopathic Gaucher disease: Rare in the West, common in the East

Gaucher disease (GD) stands as one of the most prevalent lysosomal disorders, yet neuronopathic GD (nGD) is an uncommon subset characterized by a wide array of clinical manifestations that complicate diagnosis, particularly when neurological symptoms are understated. nGD may manifest as the acute neuronopathic type, or GD type 2 (GD2), either prenatally or within the first weeks to months of life, whereas GD type 3 (GD3) symptoms may emerge at any point during childhood or occasionally in adolescence. The clinical presentation encompasses severe systemic involvement to mild visceral disease, often coupled with a spectrum of progressive neurological signs and symptoms such as cognitive impairment, ataxia, seizures, myoclonus, varying degrees of brainstem dysfunction presenting with stridor, apneic episodes, and/or impaired swallowing. This manuscript aims to provide a comprehensive review of the incidence, distinctive presentations, and diverse clinical phenotypes of nGD across various countries and regions. It will explore the natural history of the neurodegenerative process in GD, shedding light on its various manifestations during infancy and childhood, and offer insights into the diagnostic journey, the challenges faced in the clinical management, and current and investigative therapeutic approaches for GD's neurological variants.

A review of type 3 Gaucher disease: unique neurological manifestations and advances in treatment

Gaucher disease (GD) is a rare lysosomal storage disease that is caused by mutations in the GBA gene. It is classified into three main phenotypes according to the patient's clinical presentation. Of these, chronic neuronopathic GD (GD3) is characterized by progressive neurological damage. Understanding the unique neurological manifestations of GD3 has important diagnostic and therapeutic implications. Our article summarizes the neurological symptoms specific to GD3 and related therapeutic advances, and it highlights the relevance of the gene to clinical symptoms, so as to provide a reference for the diagnosis and treatment of GD3.

Allele frequency of pathogenic variants causing acid sphingomyelinase deficiency and Gaucher disease in the general Japanese population

Acid sphingomyelinase deficiency (ASMD) and Gaucher disease (GD) are lysosomal storage disorders associated with hepatosplenomegaly and thrombocytopenia. The incidences of ASMD and GD are known to be particularly high in the Ashkenazi Jewish population. Conversely, the number of reported patients with these diseases has been limited in Asian countries, including Japan. Here, we reviewed the allele frequencies of pathogenic variants causing ASMD and GD in the Japanese population and populations with various ancestry backgrounds using the Japanese Multi-Omics Reference Panel 54KJPN and the Genome Aggregation Database v4.0.0. The estimated carrier frequencies of ASMD- and GD-related variants were 1/180 and 1/154 in Japanese individuals, equivalent to disease occurrence frequencies of 1/128,191 and 1/94,791 individuals, respectively. These frequencies are much higher than previously expected. Our data also suggest that there are more patients with a milder form of ASMD and nonspecific clinical findings who have not yet been diagnosed.

c.754T>A homozygous mutation described for the first time in three Moroccan patients with Gaucher disease

Gaucher disease (GD) is a lysosomal storage disorder caused by glucocerebrosidase (GBA) deficiency. There are three subcategories of GD: Type 1 is characterized by the absence of primary central nervous system involvement; type 2 is an acute neuropathic disorder; and type 3 is chronic neuropathic. The correlation between genotype and phenotype is sometimes difficult to establish. The F213I (c.754T>A p.Phe252Ile) mutation was reported to be a unique mutation in Asia. To our knowledge, this is the first time the c.754T>A p.(Phe252Ile) mutation (homozygous state) is reported in a Moroccan population and is associated with GD type 2 (two patients) and GD type 3 (one patient).

Comprehensive and long-term outcomes of enzyme replacement therapy followed by stem cell transplantation in children with Gaucher disease type 1 and 3

BACKGROUND

Gaucher disease (GD) is a lysosomal storage disorder, characterized by hepatosplenomegaly, pancytopenia, bone diseases, with or without neurological symptoms. Plasma glucosylsphingosine (lyso-Gb1), a highly sensitive and specific biomarker for GD, has been used for diagnosis and monitoring the response to treatment. Enzyme replacement therapy (ERT) is an effective treatment for the non-neurologic symptoms of GD. Neuronopathic GD (type 2 and 3) accounts for 60%-70% of the Asian affected population.

METHODS

We explored combination therapy of ERT followed by hematopoietic stem cell transplantation (HSCT) and its long-term outcomes in patients with GD type 3 (GD3).

RESULTS

Four patients with GD3 and one with GD type 1 (GD1) underwent HSCT. The types of donor were one matched-related, one matched-unrelated, and three haploidentical. The age at disease onset was 6-18 months and the age at HSCT was 3.8-15 years in the patients with GD3. The latest age at follow-up was 8-22 years, with a post-HSCT duration of 3-14 years. All patients had successful HSCT. Chronic graft-versus-host disease occurred in one patient. The enzyme activities were normalized at 2 weeks post HSCT. Lyso-Gb1 concentrations became lower than the pathological value. All of the patients are still alive and physically independent. Most of them (4/5) returned to school. None of the patients with GD3 had seizures or additional neurological symptoms after HSCT, but showed varying degrees of cognitive impairment.

CONCLUSIONS

ERT followed by HSCT could be considered as an alternative treatment for patients with GD3 who have a high risk of fatal neurological progression.

Patient centered guidelines for the laboratory diagnosis of Gaucher disease type 1

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder due to the deficient activity of the acid beta-glucosidase (GCase) enzyme, resulting in the progressive lysosomal accumulation of glucosylceramide (GlcCer) and its deacylated derivate, glucosylsphingosine (GlcSph). GCase is encoded by the GBA1 gene, located on chromosome 1q21 16 kb upstream from a highly homologous pseudogene. To date, more than 400 GBA1 pathogenic variants have been reported, many of them derived from recombination events between the gene and the pseudogene. In the last years, the increased access to new technologies has led to an exponential growth in the number of diagnostic laboratories offering GD testing. However, both biochemical and genetic diagnosis of GD are challenging and to date no specific evidence-based guidelines for the laboratory diagnosis of GD have been published. The objective of the guidelines presented here is to provide evidence-based recommendations for the technical implementation and interpretation of biochemical and genetic testing for the diagnosis of GD to ensure a timely and accurate diagnosis for patients with GD worldwide. The guidelines have been developed by members of the Diagnostic Working group of the International Working Group of Gaucher Disease (IWGGD), a non-profit network established to promote clinical and basic research into GD for the ultimate purpose of improving the lives of patients with this disease. One of the goals of the IWGGD is to support equitable access to diagnosis of GD and to standardize procedures to ensure an accurate diagnosis. Therefore, a guideline development group consisting of biochemists and geneticists working in the field of GD diagnosis was established and a list of topics to be discussed was selected. In these guidelines, twenty recommendations are provided based on information gathered through a systematic review of the literature and two different diagnostic algorithms are presented, considering the geographical differences in the access to diagnostic services. Besides, several gaps in the current diagnostic workflow were identified and actions to fulfill them were taken within the IWGGD. We believe that the implementation of recommendations provided in these guidelines will promote an equitable, timely and accurate diagnosis for patients with GD worldwide.

Early diagnosis of Gaucher disease in Korean patients with unexplained splenomegaly: a multicenter observational study

Background

Gaucher disease (GD) is an autosomal recessive disorder characterized by excessive accumulation of glucosylceramide in multiple organs. This study was performed to determine the detection rate of GD in a selected patient population with unexplained splenomegaly in Korea.

Methods

This was a multicenter, observational study conducted at 18 sites in Korea between December 2016 and February 2020. Adult patients with unexplained splenomegaly were enrolled and tested for β-glucosidase enzyme activity on dried blood spots (DBS) and in peripheral blood leukocytes. Mutation analysis was performed if the test was positive or indeterminate for the enzyme assay. The primary endpoint was the percentage of patients with GD in patients with unexplained splenomegaly.

Results

A total of 352 patients were enrolled in this study (male patients, 199; mean age, 48.42 yr). Amongst them, 14.77% of patients had concomitant hepatomegaly. The most common sign related to GD was splenomegaly (100%), followed by thrombocytopenia (44.32%) and, anemia (40.91%). The β-glucosidase activity assay on DBS and peripheral leukocytes showed abnormal results in sixteen and six patients, respectively. Eight patients were tested for the mutation, seven of whom were negative and one patient showed a positive mutation analysis result. One female patient who presented with splenomegaly and thrombocytopenia was diagnosed with type 1 GD. The detection rate of GD was 0.2841% (exact 95% CI, 0.0072‒1.5726).

Conclusion

The detection rate of GD in probable high-risk patients in Korea was lower than expected. However, the role of hemato-oncologists is still important in the diagnosis of GD.

Clinical Characteristics, Molecular Background, and Survival of Egyptian Patients With Gaucher Disease Over a 20-Year Follow-up

This study analyzes the general disease characteristics, impact of enzyme replacement therapy (ERT), and overall survival (OS) of 156 Egyptian patients with Gaucher disease (GD) enrolled on hormone replacement from 1998 to 2017. The mean age at diagnosis was 32.46±12.68 months. Anemia was noted at diagnosis in 50%, thrombocytopenia in 30.7%, severe splenomegaly in 58.7%, severe hepatomegaly in 11.9%, and skeletal findings were detected in 24.3% of the patients. The most prevalent GD type was type 3 (54.5%). Twenty-two of type 3 patients had no neurological manifestations at diagnosis, and 12 developed variable central nervous system manifestations during follow-up. The most common neurological features were limited eye movements, oculomotor apraxia, and squint. Of the 60 patients for whom genotypes were obtained, homozygous L444P was the most common (n=35/60, 58.3%). Treatment with ERT (imiglucerase) revealed significant improvements in blood indices, organ volumes, and growth parameters (P<0.05). Ten (11.7%) type 3 patients did not develop any neurological manifestations under ERT over 20 years. Mortality was 16%, and the 20-year OS was 73.3%. We conclude that in Egypt, type 3 is the most prevalent phenotype of GD, and homozygous L444P is the predominant GBA genotype of GD. Early age at diagnosis and treatment with ERT over 20 years revealed significant improvements in disease manifestations, with an OS of 73.3%.

Gaucher disease: clinical phenotypes and refining GBA mutational spectrum in Thai patients

BACKGROUND

Gaucher disease (GD) is a rare lysosomal storage disorder, characterized by hepatosplenomegaly and pancytopenia, with or without neurologic involvement. The disorder is categorized into three phenotypes: GD type 1 or nonneuronopathic GD; GD type 2 or acute neuronopathic GD; and GD type 3 or chronic neuronopathic GD. The purposes of this study were to describe clinical characteristics of Thai GD in patients diagnosed and/or followed up during 2010-2018 and to perform re-genotyping including analysis of GBA recombinant alleles which had not been investigated in Thai patients before.

RESULTS

There were 27 patients from seven medical centers, enrolled in the study. All the cases had pediatric onset. GD3 (44.5%) was the most common phenotype, followed by GD2 (40.7%) and GD1 (14.8%), with one case of neonatal GD. The median age of onset for GD1, GD2, and GD3 was 72, 4 and 12 months, respectively, suggesting relatively earlier onset of GD1 and GD3 in Thai patients. All patients with GD1 and most patients with GD3 received ERT. Four patients with GD3 had ERT followed by HSCT. Patients with GD3 who received no or late ERT showed unfavorable outcomes. We identified 14 variants including two novel (p.S384F and p.W533*) and 12 reported pathogenic variants: p.L483P, p.N409S, p.R159W, p.P305A, p.A175G, p.D448H, p.V414L, IVS2+1G>A, IVS6-1G>C, IVS7+1G>C, IVS9-3C>G, and Rec1a. The p.L483P was the most prevalent allele found in this study, at 66% (33/50 alleles), followed by IVS2+1G>A, Rec1a, and IVS6-1G>C. Twenty-four percent of patients were reassigned with validated genotypes, most of whom (4 of 6) were patients with GD2. The [p.S384F + p.W533*] being compounded with p.L483P, was found in the patient with neonatal GD, suggesting that the p.S384F could potentiate the deleterious effect of the p.W533*, and/or vice versa.

CONCLUSIONS

Neuronopathic GD was strikingly prevalent among Thai affected population. Homozygous p.L483P was the most common genotype identified in Thai patients. Recombinant allele Rec1a and splicing mutations were associated with GD2 and severe cases of GD3. Mutation spectrum could be useful for designing stepwise molecular analysis, genetic screenings in population, and new therapeutic research for neuronopathic GD.

Long-term safety and effectiveness of velaglucerase alfa in Gaucher disease: 6-year interim analysis of a post-marketing surveillance in Japan

BACKGROUND

Gaucher disease (GD) is caused by reduced lysosomal enzyme β-glucocerebrosidase activity. Heterogeneous genotypes and phenotypes have been observed within GD types and across ethnicities. Enzyme replacement therapy is generally recommended for patients with type 1 GD, the least severe form of GD. In Japan, velaglucerase alfa has a broad indication covering type 1, 2 or 3 GD.  METHODS: All patients with type 1, 2, or 3 GD administered velaglucerase alfa 60 U/kg every 2 weeks via intravenous infusion after its launch date in Japan in 2014, were enrolled in a non-interventional, observational post-marketing surveillance (PMS). Individual patient data were reported via case report forms (CRFs). Key safety endpoints investigated included the incidence of infusion-related reactions (IRRs), the safety of velaglucerase alfa in patients with types 2 and 3 GD, from patients under one year of age to elderly patients (≥ 65 years of age). Long-term efficacy was also assessed.  RESULTS: In total, 53 patients with GD were registered. CRFs were available for 41 (77.4%) patients at the 6-year interim analysis. Fourteen adverse drug reactions (ADRs) were reported in seven patients. All reported ADRs occurred in patients with type 2 GD. ADRs were reported by 63.6% (7/11) of patients with type 2 GD. Ten ADRs were reported in five patients aged < 4 years. No elderly patients experienced any ADR during the surveillance period. Five ADRs occurring in three (10.0%) patients were classified as IRRs, with one case of vomiting (moderate severity) resulting in treatment discontinuation. Ten serious adverse events were reported in five (16.7%) patients. Three fatal events were considered to be unrelated to treatment with velaglucerase alfa. Platelet counts increased after the administration of velaglucerase alfa and were generally maintained within the normal range over the administration period. Among eleven patients tested for neutralizing anti-velaglucerase alfa antibodies, two (18.2%) were assessed as positive results.  CONCLUSION: PMS data from patients with types 1-3 GD in Japan indicate that long-term treatment with velaglucerase alfa was well-tolerated and associated with increased platelet counts, which is consistent with observations made in studies outside of Japan.

TRIAL REGISTRATION

NCT03625882 registered July 2014.

Current and emerging pharmacotherapy for Gaucher disease in pediatric populations

INTRODUCTION

The past decades have witnessed a remarkable improvement in the health of patients with Gaucher disease, the inherited deficiency of the lysosomal enzyme glucocerebrosidase, resulting from the availability of enzyme replacement and substrate reduction therapies. Especially in pediatric populations, early diagnosis and initiation of treatment is essential to achieving optimal outcomes.

AREAS COVERED

The authors review the literature pertaining to the effectiveness of currently available therapies and describe new pharmacotherapies under development, especially for young patients.

EXPERT OPINION

For pediatric patients with non-neuronopathic Gaucher disease, there may be new therapeutic options on the horizon in the form of gene therapy or small molecule glucocerebrosidase chaperones. These have the potential to result in a cure for systemic disease manifestations and/or to reduce the cost and convenience of treatment. For children with neuronopathic Gaucher disease, the challenge of targeting therapy to the central nervous system is being explored through new modalities including brain-targeted gene therapy, in-utero therapy, brain-penetrant small molecule chaperones, and other methods that convey enzyme across the blood-brain barrier. Indeed, these are exciting times for both pediatric patients with Gaucher disease and those with other lysosomal storage disorders.

The GBA p.G85E mutation in Korean patients with non-neuronopathic Gaucher disease: founder and neuroprotective effects

Background

Gaucher disease (GD) is caused by a deficiency of β-glucocerebrosidase, encoded by GBA. Haplotype analyses previously demonstrated founder effects for particular GBA mutations in Ashkenazi Jewish and French-Canadian populations. This study aimed to investigate the clinical characteristics and mutation spectrum of GBA in Korean GD patients and to identify founder effect of GBA p.G85E in non-neuronopathic GD patients.

Results

The study cohort included 62 GD patients from 58 unrelated families. Among them, 18 patients from 17 families harbored the p.G85E mutation. Haplotype analysis was performed for 9 probands and their parents for whom DNA samples were available. In 58 unrelated probands, the GBA mutation p.L483P was the most common (30/116 alleles, 26%), followed by p.G85E (16%), p.F252I (13%), and p.R296Q (9%). The median age at diagnosis of the 18 patients harboring the p.G85E mutation was 3.8 (range 1.2–57) years. No patients developed neurological symptoms during follow-up periods of 2.2–20.3 (median 13.9) years. The size of the shared haplotype containing GBA p.G85E was 732 kbp, leading to an estimated age of 3075 years.

Conclusion

The GBA p.G85E mutation, which appears to be neuroprotective despite producing distinctive visceromegaly and skeletal symptoms, exhibited a potential founder effect in Korean GD patients.

Intravenous infusion of iPSC-derived neural precursor cells increases acid β-glucosidase function in the brain and lessens the neuronopathic phenotype in a mouse model of Gaucher disease

Gaucher disease (GD) is caused by GBA1 mutations leading to functional deficiency of acid-β-glucosidase (GCase). No effective treatment is available for neuronopathic GD (nGD). A subclass of neural stem and precursor cells (NPCs) expresses VLA4 (integrin α4β1, very late antigen-4) that facilitates NPC entry into the brain following intravenous (IV) infusion. Here, the therapeutic potential of IV VLA4+NPCs was assessed for nGD using wild-type mouse green fluorescent protein (GFP)-positive multipotent induced pluripotent stem cell (iPSC)-derived VLA4+NPCs. VLA4+NPCs successfully engrafted in the nGD (4L;C*) mouse brain. GFP-positive cells differentiated into neurons, astrocytes and oligodendrocytes in the brainstem, midbrain and thalamus of the transplanted mice and significantly improved sensorimotor function and prolonged life span compared to vehicle-treated 4L;C* mice. VLA4+NPC transplantation significantly decreased levels of CD68 and glial fibrillary acidic protein, as well as TNFα mRNA levels in the brain, indicating reduced neuroinflammation. Furthermore, decreased Fluoro-Jade C and NeuroSilver staining suggested inhibition of neurodegeneration. VLA4+NPC-engrafted 4L;C* midbrains showed 35% increased GCase activity, reduced substrate [glucosylceramide (GC, -34%) and glucosylsphingosine (GS, -11%)] levels and improved mitochondrial oxygen consumption rates in comparison to vehicle-4L;C* mice. VLA4+NPC engraftment in 4L;C* brain also led to enhanced expression of neurotrophic factors that have roles in neuronal survival and the promotion of neurogenesis. This study provides evidence that iPSC-derived NPC transplantation has efficacy in an nGD mouse model and provides proof of concept for autologous NPC therapy in nGD.

Mechanism of glucocerebrosidase activation and dysfunction in Gaucher disease unraveled by molecular dynamics and deep learning

The lysosomal enzyme glucocerebrosidase-1 (GCase) catalyzes the cleavage of a major glycolipid glucosylceramide into glucose and ceramide. The absence of fully functional GCase leads to the accumulation of its lipid substrates in lysosomes, causing Gaucher disease, an autosomal recessive disorder that displays profound genotype-phenotype nonconcordance. More than 250 disease-causing mutations in GBA1, the gene encoding GCase, have been discovered, although only one of these, N370S, causes 70% of disease. Here, we have used a knowledge-based docking protocol that considers experimental data of protein-protein binding to generate a complex between GCase and its known facilitator protein saposin C (SAPC). Multiscale molecular-dynamics simulations were used to study lipid self-assembly, membrane insertion, and the dynamics of the interactions between different components of the complex. Deep learning was applied to propose a model that explains the mechanism of GCase activation, which requires SAPC. Notably, we find that conformational changes in the loops at the entrance of the substrate-binding site are stabilized by direct interactions with SAPC and that the loss of such interactions induced by N370S and another common mutation, L444P, result in destabilization of the complex and reduced GCase activation. Our findings provide an atomistic-level explanation for GCase activation and the precise mechanism through which N370S and L444P cause Gaucher disease.

Neuronopathic Gaucher disease presenting with microcytic hypochromic anemia

Gaucher disease (GD) is caused by a hereditary deficiency of glucocerebrosidase, resulting in accumulation of glucosylceramide and potentially manifesting as hepatosplenomegaly. We report the case of a 15-month-old boy with chronic neuronopathic GD. The patient had prolonged anemia despite continued iron supplementation for 3 months. White blood count (WBC), hemoglobin (Hb), platelet count, and corrected reticulocyte count were 3,300 /µL, 8.7 g/dL, 90,000 /µL, and 0.55, respectively. The patient had microcytic hypochromic anemia with mildly elevated ferritin. Physical examination revealed hepatosplenomegaly. Bone-marrow aspiration showed sheets of Gaucher cells. Glucocerebrosidase activity in monocytes was significantly lower than normal. Genetic analysis revealed a homozygous L444P mutation of GBA, and he was diagnosed with type 1 GD. Enzyme replacement treatment (ERT) consisting of imiglucerase was initiated and was effective; WBC, Hb, and platelet count gradually normalized and the hepatosplenomegaly improved. However, when the patient entered elementary school, he showed mild impaired cognitive function, and supranuclear gaze palsy occurred the same year. He was ultimately diagnosed with type 3 GD and continued ERT. Pediatric hemato-oncologists should be aware of GD, especially when patients exhibit anemia refractory to iron therapy, radiologic bone deformity, neurologic signs or symptoms, and growth retardation.

Genotypes and phenotypes in 20 Chinese patients with type 2 Gaucher disease

BACKGROUND

Gaucher disease (GD) is one of the most common lysosomal storage diseases resulting from a deficiency of glucocerebrosidase. Three main types have been described, with type 2 being the most rare and severe form. Here we investigated the clinical symptoms and mutation spectrum in 20 unrelated type 2 GD patients.

METHOD

The diagnosis of GD was based on the acid β-glucocerebrosidase (GBA) enzyme activity and direct sequencing of the GBA gene. GBA activity was measured in leukocytes and the GBA gene was amplified by a polymerase chain reaction (PCR). For patient 7, the GBA gene was analyzed by PCR as well as quantitative real-time PCR.

RESULTS

The age of onset was under 12 months for all patients. All patients experienced severe neurological involvement. A total of 19 different GBA gene mutations were identified, including 6 novel mutations: two were exonic point mutations, c.1127T > C (p.Phe376Ser), c.1418T > G (p.Val473Gly); one was splicing error, ISV7-1G > C; one was insertion, c.717_718insACAG; and the other two were a gross deletion that involved exon 6 and a recombinant allele. The most prevalent mutation was Leu483Pro, which constituted 42.5% of all mutant alleles and was associated with a neurological form in Chinese GD patients as calculated by a Fisher's exact test.

CONCLUSION

The clinical characteristics of Chinese type 2 GD were consistent with reports from other ethnic populations. We identified 6 novel mutations that contribute to the spectrum of GBA gene mutations. Our study confirmed that GD patients with the Leu483Pro allele were prone to experience neurological symptoms.

Characteristics of 26 patients with type 3 Gaucher disease: A descriptive analysis from the Gaucher Outcome Survey

The Gaucher Outcome Survey (GOS) is an international disease-specific registry established in 2010 for patients with a confirmed diagnosis of Gaucher disease (GD), regardless of GD type or treatment status. Historically, there has been a limited understanding of type 3 GD (GD3) and its natural history in patients irrespective of their treatment status. Here, we describe the disease characteristics of patients with GD3 enrolled in GOS. As of October 2015, 1002 patients had been enrolled, 26 of whom were reported as GD3. The majority of patients with GD3 were from the US (13; 50.0%), seven (26.9%) were from the UK, three (11.5%) from Israel, and three (11.5%) from Brazil. No patients were of Ashkenazi Jewish origin. Median age of symptom onset was 1.4 (interquartile range: 0.5–2.0) years. The most common GBA1 mutation genotype was L444P/L444P, occurring in 16 (69.6%) of 23 patients who had genotyping information available. Nine patients reported a family history of GD (any type). Of 21 patients with treatment status information, 20 (95.2%) had received GD-specific treatment at any time, primarily imiglucerase (14 patients) and/or velaglucerase alfa (13 patients). Hemoglobin concentrations and platelet counts at GOS entry were within normal ranges for most patients, and there were no reports of severe hepatomegaly or of splenomegaly in non-splenectomized patients, most likely indicative of the effects of treatment received prior to GOS entry. This analysis provides information on the characteristics of patients with GD3 that could be used as the baseline for longitudinal follow-up of these patients.

Laboratory diagnosis and follow-up of Romanian Gaucher disease patients

Background: Gaucher disease (GD) is caused by a recessively inherited deficiency of glucocerebrosidase which is encoded by the GBA gene in which nearly 450 mutations have been described. However, only a few genotype- phenotype correlations have been clearly established. The aim of this study was to investigate molecular features of GD in Romanian patients and to evaluate their impact on treatment response. Material and methods: 69 patients, diagnosed between 1997 and 2014 at our national referral laboratory, were included in this study. Frequent point mutations (N370S, L444P, 84GG, R463C) were detected by amplification and restriction enzyme digestion. Recombinant alleles (recTL, recNciI, recA456P) were screened by DNA sequencing. Plasma chitotriosidase served as a biomarker of disease severity throughout the follow-up period. Results: 66 patients had the non-neuronopathic (type 1) form of GD and 3 had the chronic neuronopathic (type 3) phenotype. We identified 79% of the mutant alleles, among which the most frequent mutations were N370S (54%) and L444P (18%). We found a statistically significant (p<0.001) and moderate to good correlation between the total therapeutic dose and the residual chitotriosidase activity (R = 0.621). After two years of treatment, we noticed statistically significant variations in chitotriosidase activity corresponding to the most frequent genotypes (N370S/ unknown allele, N370S/L444P, N370S/N370S and N370S/R463Q). Conclusions: Allele distribution displayed specific features in Romanian GD patients, such as the high prevalence of the N370S allele. Chitotriosidase activity measurement allowed the investigation of genotype influence on treatment outcome.

Successful newborn screening for Gaucher disease using fluorometric assay in China

Gaucher disease (GD) is an inherited metabolic disorder that involves accumulation of glycolipid glucocerebroside in monocyte–macrophage cells, which can result in multiple organ damage. Enzyme replacement and substrate reduction therapies have improved the potential for early diagnosis and treatment. Determining the true incidence of this rare disease is critical for relevant policy establishment. Newborn screening allows for early diagnosis and an comparatively accurate incidence of GD. A fluorometric method to detect acid β-glucocerebrosidase (GBA) activity on a dried blood spot punch was developed. Validity and feasibility of the fluorometric method was demonstrated by examining 116 healthy controls, 19 confirmed GD patients and 19 obligate carriers. GBA activity was measured on dried blood spots of 80 855 newborns. Samples from positively screened newborns were reanalyzed by a leukocyte GBA activity test and GBA gene analysis. Plasma glucosylsphingosine level was determined as a biomarker of the pathophysiology of GD. GD patients were distinguished from healthy controls and obligate carriers using the fluorometric method. Mean GBA activity in newborn screening specimens was 145.69±44.76 μmol l⁻¹ h⁻¹ (n=80 844). Three children had low GBA activity, of which one child had low GBA activity on the second dried blood spot specimen. Leukocyte, genetic and biomarker analysis confirmed the diagnosis and indicated that this child was in the early stages of GD. In conclusion, the incidence of GD in Shanghai of China is approximately 1 in 80 855. Screening for GD by fluorometric analysis of GBA activity is an efficient and feasible technology in newborns.

Long-term hematological, visceral, and growth outcomes in children with Gaucher disease type 3 treated with imiglucerase in the International Collaborative Gaucher Group Gaucher Registry

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.

Long-term follow-up and sudden unexpected death in Gaucher disease type 3 in Egypt

Objective:

To describe the long-term follow-up and distinct phenotype of a large cohort of patients with Gaucher disease type 3 on enzyme replacement therapy (ERT) in Egypt.

Methods:

A prospective cohort study of 78 patients on ERT who were followed for up to 9 years with yearly evaluations that included EEG and cognitive testing.

Results:

Of the patients, 73% were homozygous for the L444P GBA1 mutation; all but 7 were neurologically symptomatic. Supranuclear gaze palsy with variable but stable cognitive function was present in 91% of patients. Convergent strabismus and bulbar dysfunction were noted in 22% and 37%, respectively. Features of oppositional defiant disorder were present in 54% of patients. Twenty-three patients (30%) developed seizures while on ERT for 1–9 years. Of those, 12 patients (15%) died suddenly and unexpectedly at a mean age of 6.7 ± 5.0 years (range 1.5–18). Sudden death was usually associated with a seizure disorder or a terminal seizure, but 7 of 12 patients had a preceding normal EEG. An additional 11% had background slowing or epileptogenic activity on EEG without clinical seizures. There were 3 familial cases of sudden unexpected death.

Conclusions:

Despite having the most common GBA1 genotype known to be associated with neuronopathic Gaucher disease, patients with Gaucher disease type 3 in Egypt have a phenotype and a clinical outcome on ERT that are very different from those observed in other populations. Identifying putative modifying genes of this ethnic group is likely to lead to better therapy for neuronopathic Gaucher disease generally.

Ambroxol chaperone therapy for neuronopathic Gaucher disease: A pilot study

Objective

Gaucher disease (GD) is a lysosomal storage disease characterized by a deficiency of glucocerebrosidase. Although enzyme‐replacement and substrate‐reduction therapies are available, their efficacies in treating the neurological manifestations of GD are negligible. Pharmacological chaperone therapy is hypothesized to offer a new strategy for treating the neurological manifestations of this disease. Specifically, ambroxol, a commonly used expectorant, has been proposed as a candidate pharmacological chaperone. The purpose of this study was to evaluate the safety, tolerability, and neurological efficacy of ambroxol in patients with neuronopathic GD.

Methods

This open‐label pilot study included five patients who received high‐dose oral ambroxol in combination with enzyme replacement therapy. Safety was assessed by adverse event query, physical examination, electrocardiography, laboratory studies, and drug concentration. Biochemical efficacy was assessed through evidence of glucocerebrosidase activity in the lymphocytes and glucosylsphingosine levels in the cerebrospinal fluid. Neurological efficacy was evaluated using the Unified Myoclonus Rating Scale, Gross Motor Function Measure, Functional Independence Measure, seizure frequency, pupillary light reflex, horizontal saccadic latency, and electrophysiologic studies.

Results

High‐dose oral ambroxol had good safety and tolerability, significantly increased lymphocyte glucocerebrosidase activity, permeated the blood–brain barrier, and decreased glucosylsphingosine levels in the cerebrospinal fluid. Myoclonus, seizures, and pupillary light reflex dysfunction markedly improved in all patients. Relief from myoclonus led to impressive recovery of gross motor function in two patients, allowing them to walk again.

Interpretation

Pharmacological chaperone therapy with high‐dose oral ambroxol shows promise in treating neuronopathic GD, necessitating further clinical trials.

Understanding the natural history of Gaucher disease

Gaucher disease is a rare and extraordinarily heterogeneous inborn error of metabolism that exhibits diverse manifestations, a broad range of age of onset of symptoms, and a wide clinical spectrum of disease severity, from lethal disease during infancy to first age of onset of symptoms in octogenarians. Before the advent of the International Collaborative Gaucher Group (ICGG) Gaucher Registry, the understanding of the natural history and phenotypic range of Gaucher disease was based on isolated case reports and small case series. Limited data hindered understanding of the full spectrum of the disease leading to some early misconceptions about Gaucher disease, notably, that nonneuronopathic (type 1) disease was a disease of adults only. The global scope of the ICGG Gaucher Registry, with its vast body of longitudinal data, has enabled a real appreciation of both the phenotypic spectrum of Gaucher disease and its natural history. This body of evidence represents the foundation for accurate assessment of the response to specific therapies for Gaucher disease and to the development of standard-of-care to monitor disease activity. Here, we outline the key developments in delineating the natural history of this highly complex disease and role of the ICGG Gaucher Registry in this effort.

Ubiquitous transgene expression of the glucosylceramide-synthesizing enzyme accelerates glucosylceramide accumulation and storage cells in a Gaucher disease mouse model

Gaucher disease is a lysosomal storage disease caused by defective activity of acid β-glucosidase (GCase), which leads to the accumulation of its major substrates, glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph) in many cells. To modulate cellular substrate concentration in viable mouse models of Gaucher disease (Gba1 mutants), a novel mouse model was created with enhanced glycosphingolipid biosynthesis. This was accomplished by cross-breeding Gba1 mutant mice with mice expressing a transgene (GCStg) containing the mouse glucosylceramide synthase (GCS, Ugcg) cDNA driven by the ROSA promoter, yielding GCStg/Gba1 mice. The GCStg rescued Ugcg null mice from embryonic lethality. GCStg/Gba1 mice showed 2-3 fold increases in tissue GCS activity as well as accelerated GlcCer accumulation and the appearance of lipid-laden CD68 positive macrophages in visceral organs. Although GlcCer/GlcSph concentrations were elevated in the brain, there was no neurodegenerative phenotype up to 1 yr of age conceivably due to the greater residual GCase hydrolytic activity in the brains than in the visceral tissues of 9V/null mice. These studies provide 'proof of principle' for threshold substrate flux that modifies phenotypic development in Gaucher disease and other lysosomal storage diseases.

Glucocerebrosidase mutations in Thai patients with Parkinson's disease

BACKGROUND

GBA mutations are an important risk factor in developing Parkinson's disease (PD) worldwide. The study aimed to determine the frequency and clinical characteristics of GBA mutations in a Thai PD cohort of 480 patients and 395 control subjects.

METHODS

Direct sequencing of GBA was performed in all early-onset PD patients (EOPD: n = 108) and 100 PD patients with age at onset over 50 years (AAO > 50y-PD). The study subsequently screened all identified mutations in the remaining AAO > 50y-PD patients and all control subjects. Predictive factors associated with risk of developing PD were analyzed. Comparisons of clinical characteristics of PD patients with and without GBA mutations were also carried out.

RESULTS

Heterozygous GBA mutations were identified in 24 patients (5%) and 2 controls (0.5%). Seven identified GBA point mutations comprised p.L444P, p.N386K, p.P428S, IVS2+1G > A, IVS9+3G > C, IVS10-9_10GT > AG and c.1309delG, of which five mutations were novel. Multiple logistic regression analysis revealed that GBA mutations were more frequent in EOPD than AAO > 50y-PD groups (OR = 4.64, P < 0.022). Patients with GBA mutations had mean age at onset (43.1 ± 10.2, mean ± standard deviation) earlier than patients without GBA mutations (54.4 ± 13.9, P = 0.002). The patients with GBA mutations also had a more rapid progressive course, in which they were more likely to have higher Hoehn and Yahr staging (OR = 4.20, P = 0.006) and slightly lower means of Schwab-England ADL score [74.1 ± 17.1 vs. 81.0 ± 18.08 (OR = 0.98, 95%CI = 0.96-1.01, P = 0.162)].

CONCLUSION

GBA mutations are an important risk of PD in the Thai population. Patients having the mutations are likely to have early onset and may exhibit more rapid motor progression.

Gaucher disease

Gaucher disease is the commonest lysosomal storage disease seen in India and worldwide. It should be considered in any child or adult with an unexplained splenohepatomegaly and cytopenia which are seen in the three types of Gaucher disease. Type 1 is the non-neuronopathic form and type 2 and 3 are the neuronopathic forms. Type 2 is a more severe neuronopathic form leading to mortality by 2 years of age. Definitive diagnosis is made by a blood test-the glucocerebrosidase assay. There is no role for histological examination of the bone marrow, liver or spleen for diagnosis of the disease. Molecular studies for mutations are useful for confirming diagnosis, screening family members and prognosticating the disease. A splenectomy should not be performed except for palliation or when there is no response to enzyme replacement treatment or no possibility of getting any definitive treatment. Splenectomy may worsen skeletal and lung manifestations in Gaucher disease. Enzyme replacement therapy (ERT) has completely revolutionized the prognosis and is now the standard of care for patients with this disease. Best results are seen in type 1 disease with good resolution of splenohepatomegaly, cytopenia and bone symptoms. Neurological symptoms in type 3 disease need supportive care. ERT is of no benefit in type 2 disease. Monitoring of patients on ERT involves evaluation of growth, blood counts, liver and spleen size and biomarkers such as chitotriosidase which reflect the disease burden. Therapy with ERT is very expensive and though patients in India have so far got the drug through a charitable access programme, there is a need for the government to facilitate access to treatment for this potentially curable disease. Bone marrow transplantation is an inferior option but may be considered when access to expensive ERT is not possible.

Revised recommendations for the management of Gaucher disease in children

Gaucher disease is an inherited pan-ethnic disorder that commonly begins in childhood and is caused by deficient activity of the lysosomal enzyme glucocerebrosidase. Two major phenotypes are recognized: non-neuropathic (type 1) and neuropathic (types 2 and 3). Symptomatic children are severely affected and manifest growth retardation, delayed puberty, early-onset osteopenia, significant splenomegaly, hepatomegaly, thrombocytopenia, anemia, severe bone pain, acute bone crises, and fractures. Symptomatic children with types 1 or 3 should receive enzyme replacement therapy, which will prevent debilitating and often irreversible disease progression and allow those with non-neuropathic disease to lead normal healthy lives. Children should be monitored every 6 months (physical exam including growth, spleen and liver volume, neurologic exam, hematologic indices) and have one to two yearly skeletal assessments (bone density and imaging, preferably with magnetic resonance, of lumbar vertebrae and lower limbs), with specialized cardiovascular monitoring for some type 3 patients. Response to treatment will determine the frequency of monitoring and optimal dose of enzyme replacement. Treatment of children with type 2 (most severe) neuropathic Gaucher disease is supportive. Pre-symptomatic children, usually with type 1 Gaucher, increasingly are being detected because of affected siblings and screening in high-prevalence communities. In this group, annual examinations (including bone density) are recommended. However, monitoring of asymptomatic children with affected siblings should be guided by the age and severity of manifestations in the first affected sibling. Treatment is necessary only if signs and symptoms develop.

CONCLUSION

Early detection and treatment of symptomatic types 1 and 3 Gaucher disease with regular monitoring will optimize outcome. Pre-symptomatic children require regular monitoring. Genetic counseling is important.

Imiglucerase in the treatment of Gaucher disease: a history and perspective

The scientific and therapeutic development of imiglucerase (Cerezyme(®)) by the Genzyme Corporation is a paradigm case for a critical examination of current trends in biotechnology. In this article the authors argue that contemporary interest in treatments for rare diseases by major pharmaceutical companies stems in large part from an exception among rarities: the astonishing commercial success of Cerezyme. The fortunes of the Genzyme Corporation, latterly acquired by global giant Sanofi SA, were founded on the evolution of a blockbuster therapy for a single but, as it turns out, propitious ultra-orphan disorder: Gaucher disease.

Progressive mesenteric lymphadenopathy with protein-losing enteropathy; a devastating complication in Gaucher disease

Mesenteric lymphadenopathy has been rarely reported in pediatric patients with Gaucher disease, developing despite the enzyme replacement therapy. The clinical implication of this condition is undetermined, with no consensus on treatment strategies. However, this condition can reflect the progression of Gaucher disease. Moreover, it can be accompanied by the serious complication, protein-losing enteropathy. Our experience underlines the importance of careful monitoring and early intervention for mesenteric lymphadenopathy, especially in pediatric patients with neuronopathic Gaucher disease.

Association of mutations in the glucocerebrosidase gene with Parkinson disease in a Korean population

Recent studies have shown an association between Parkinson disease (PD) and mutations in the gene encoding the lysosomal enzyme glucocerebrosidase (GBA), which is deficient in patients with Gaucher disease. In Asian populations, 2 mutational analysis studies have been performed in all exons of GBA; one study in a Japanese population showed the highest odds ratio among all ethnic groups, whereas the other study in ethnic Chinese observed a trend of a higher frequency of GBA mutation in PD patients without statistical significance. To investigate whether there is an association between PD and mutations of GBA in a Korean population, we analyzed mutations of GBA and compared mutation frequencies between Korean PD patients and a control population. We analyzed mutations in GBA by sequencing exons of GBA in 277 Korean PD patients and 291 control subjects. All exons of GBA were sequenced in all PD cases and 100 control subjects. Exon 2 and exons 5-11, where mutations of GBA were found in our PD patients, were analyzed in an additional 191 control subjects. Five different pathogenic heterozygous GBA mutations, including N188S, P201H, R257Q, S271G, and L444P, were identified in 9 PD cases (3.2%), whereas there were no GBA mutations found in control subjects (p<0.01, OR 20.6, 95% CI 1.2-356.4). The mean age-at-onset of heterozygous GBA variants carriers was younger than that of non-carriers (48.6±11.9 versus 57.9±13.5, p<0.05, Mann-Whitney test). Our results suggest that heterozygous mutations of GBA represent a risk factor for PD in Koreans.

Clinical and genetic characteristics of Gaucher disease according to phenotypic subgroups

Purpose

Gaucher disease is caused by a β-glucocerebrosidase (GBA) deficiency. The aim of this study is to investigate the clinical and genetic characteristics according to subtypes of Gaucher disease in the Korean population.

Methods

Clinical findings at diagnosis, GBA mutations, and clinical courses were reviewed in 20 patients diagnosed with Gaucher disease.

Results

Eleven patients were diagnosed with non-neuronopathic type, 2 with acute neuronopathic type, and 7 with chronic neuronopathic type. Most patients presented with hepatosplenomegaly, thrombocytopenia, and short stature. In the neuronopathic group, variable neurological features, such as seizure, tremor, gaze palsy, and hypotonia, were noted at age 8.7±4.3 years. B cell lymphoma, protein-losing enteropathy, and hydrops fetalis were the atypical manifestations. Biomarkers, including chitotriosidase, acid phosphatase, and angiotensin-converting enzyme, increased at the initial evaluation and subsequently decreased with enzyme replacement treatment (ERT). The clinical findings, including hepatosplenomegaly, thrombocytopenia, and skeletal findings, improved following ERT, except for the neurological manifestations. L444P was the most common mutation in our cohort. One novel mutation, R277C, was found.

Conclusion

Although the clinical outcome for Gaucher disease improved remarkably following ERT, the outcome differed according to subtype. Considering the high proportion of the neuronopathic form in the Korean population, new therapeutic strategies targeting the central nervous system are needed, with the development of a new scoring system and biomarkers representing clinical courses in a more comprehensive manner.

Identification of a novel recombinant mutation in Korean patients with Gaucher disease using a long-range PCR approach

Gaucher disease (GD) is an autosomal recessive, lysosomal disorder caused by mutations in the gene for the β-glucocerebrosidase (GBA) enzyme. Presence of the non-functional GBAP pseudogene, which shares high sequence similarity with the functional GBA gene, has made it difficult to carry out molecular analyses of GD, especially recombinant mutations. Using a long-range PCR approach that has been skillfully devised for the easy detection of GBA recombinant mutations, we identified four recombinant mutations including two gene conversion alleles, Rec 1a and Rec 8a, one reciprocal gene fusion allele, Rec 1b, and one reciprocal gene duplication allele, Rec 7b, in Korean patients with GD. Rec 8a, in which the GBAP pseudogene sequence from intron 5 to exon 11 is substituted for the GBA gene is a novel recombinant mutation. All mutations were confirmed by full sequencing of PCR amplicons and/or Southern blot analysis. These results indicate that the usage of long-range PCR may allow the rapid and accurate detection of GBA recombinant mutations and contribute to the improvement of genotyping efficiency in GD patients.