Gaucher's disease: clinical features and natural history

Lysosomal membrane integrity in fibroblasts derived from patients with Gaucher disease

Gaucher disease (GD) is a recessively inherited lysosomal storage disorder characterized by a deficiency of lysosomal glucocerebrosidase (GBA1). This deficiency results in the accumulation of its substrate, glucosylceramide (GlcCer), within lysosomes. Here, we investigated lysosomal abnormalities in fibroblasts derived from patients with GD. It is noteworthy that the cellular distribution of lysosomes and lysosomal proteolytic activity remained largely unaffected in GD fibroblasts. However, we found that lysosomal membranes of GD fibroblasts were susceptible to damage when exposed to a lysosomotropic agent. Moreover, the susceptibility of lysosomal membranes to a lysosomotropic agent could be partly restored by exogenous expression of wild-type GBA1. Here, we report that the lysosomal membrane integrity is altered in GD fibroblasts, but lysosomal distribution and proteolytic activity is not significantly altered.Key words: glucosylceramide, lysosome, Gaucher disease, lysosomotropic agent.

Expanding the phenotypic landscape of Gaucher disease type 3c with a novel entity - Transient neonatal cholestasis

Gaucher disease (GD) is the most frequent lysosomal storage disorder due to biallelic pathogenic variants in GBA gene. Only homozygous D409H variant has been associated with the cardiovascular phenotype which is also known as Gaucher disease type 3c. In this descriptive study, we presented phenotypic heterogeneity and a novel clinical finding among 13 patients with GD type 3c. Patients presented with varying degrees of cardiac valve and/or aortic calcifications (84,6%) and corneal opacities (76,9%) in addition to visceral (100%), hematological (92,3%), neurological (92,3%), and skeletal (30%) manifestations. Also, cervical dystonia (38,4%) and psychiatric disorders (46,1%) were not infrequent entities with respect to neurological involvement in GD type 3c. In this report, we highlight transient neonatal cholestasis (38,4%) as a novel finding in GD type 3c. Neonatal cholestasis is a finding associated with Gaucher type 2, but transient neonatal cholestasis has not been reported in GD patients, so far. The clinical features of GD type 3c are highly heterogeneous, from disease severity or age of onset to disease progression. Also, we concluded that phenotypic spectrum may be associated with age at onset of clinical symptoms. As, patients presenting in infancy or childhood had mainly visceral and hematological involvement and patients presenting in adolescence and adulthood had mainly cardiac, neurological involvement, and psychiatric behavioral disorders. Identifying the heterogeneous clinical course of these patients in this fatal disease, may lead a sufficient understanding of the pathophysiology which will enable targeted therapeutic interventions.

Suicidal attempt with eliglustat overdose

Eliglustat is an orphan medicine used for long-term treatment of Gaucher disease type 1 (GD1) in adults. GD1 is a genetic condition, in which glucosylceramide builds up in the body, typically in liver, spleen, and bone. Clinical signs and symptoms of the disease are anemia, tiredness, easy bruising, hepatosplenomegaly, bone pain, and fractures. Eliglustat works by blocking glucosylceramide synthase (substrate reduction therapy). This medicine is subject to additional safety monitoring by regulatory authorities in the European Union. Scientific literature on eliglustat overdose is not available. We herein describe successful treatment of a suicidal attempt with massive eliglustat overdose. A 29-year-old female with GD1, a poor metabolizer of cytochrome P450 2D6 on a recommended daily dose of 84 mg of eliglustat, had taken 94 capsules of eliglustat (84 mg per capsule). One hour after ingestion of almost 8 g of eliglustat, the patient suffered from somnolence, severe bradycardia (37 bpm), and hypotension (systolic blood pressure of 70 mm Hg). After intravenous administration of atropine (1 mg) and cafedrine/theoadrenaline (100 mg/5 mg) by the called emergency physician, the patient resolved gradually. She remained 24 h with stable hemodynamics at a nearby intensive care unit. During continuous ECG monitoring, increased frequency of supraventricular ectopic activity and a first-degree atrioventricular block were observed. To our knowledge, this is the first case report on a suicidal attempt with eliglustat.

Natural history and management of liver dysfunction in lysosomal storage disorders

Lysosomal storage disorders (LSD) are a rare group of genetic disorders. The major LSDs that cause liver dysfunction are disorders of sphingolipid lipid storage [Gaucher disease (GD) and Niemann-Pick disease] and lysosomal acid lipase deficiency [cholesteryl ester storage disease and Wolman disease (WD)]. These diseases can cause significant liver problems ranging from asymptomatic hepatomegaly to cirrhosis and portal hypertension. Abnormal storage cells initiate hepatic fibrosis in sphingolipid disorders. Dyslipidemia causes micronodular cirrhosis in lipid storage disorders. These disorders must be keenly differentiated from other chronic liver diseases and non-alcoholic steatohepatitis that affect children and young adults. GD, Niemann-Pick type C, and WD also cause neonatal cholestasis and infantile liver failure. Genotype and liver phenotype correlation is variable in these conditions. Patients with LSD may survive up to 4-5 decades except for those with neonatal onset disease. The diagnosis of all LSD is based on enzymatic activity, tissue histology, and genetic testing. Enzyme replacement is possible in GD and Niemann-Pick types A and B though there are major limitations in the outcome. Those that progress invariably require liver transplantation with variable outcomes. The prognosis of Niemann-Pick type C and WD is universally poor. Enzyme replacement therapy has a promising role in cholesteryl ester storage disease. This review attempts to outline the natural history of these disorders from a hepatologist’s perspective to increase awareness and facilitate better management of these rare disorders.

Phagocytosis of Erythrocytes from Gaucher Patients Induces Phenotypic Modifications in Macrophages, Driving Them toward Gaucher Cells

Gaucher disease (GD) is caused by glucocerebrosidase deficiency leading to the accumulation of sphingolipids in macrophages named “Gaucher’s Cells”. These cells are characterized by deregulated expression of cell surface markers, abnormal secretion of inflammatory cytokines, and iron sequestration. These cells are known to infiltrate tissues resulting in hematological manifestations, splenomegaly, and bone diseases. We have already demonstrated that Gaucher red blood cells exhibit altered properties suggesting their key role in GD clinical manifestations. We hypothesized that Gaucher’s erythrocytes could be prone to premature destruction by macrophages contributing to the formation of altered macrophages and Gaucher-like cells. We conducted in vitro experiments of erythrophagocytosis using erythrocytes from Gaucher’s patients or healthy donors. Our results showed an enhanced erythrophagocytosis of Gaucher red blood cells compared to healthy red blood cells, which is related to erythrocyte sphingolipids overload and reduced deformability. Importantly, we showed elevated expression of the antigen-presenting molecules CD1d and MHC-II and of the iron-regulator hepcidin in macrophages, as well as enhanced secretion of the pro-inflammatory cytokine IL-1β after phagocytosis of GD erythrocytes. These results strongly suggested that erythrophagocytosis in GD contribute to phenotypic modifications in macrophages. This present study shows that erythrocytes-macrophages interactions may be crucial in GD pathophysiology and pathogenesis.

Long-term eliglustat treatment of Gaucher patients over up to 10 years in Vienna

Gaucher disease has been the first lysosomal storage disorder for which an enzyme replacement therapy has been approved in the 1990s and was the first to receive approval for a first-line substrate reduction therapy in 2015. Eliglustat treatment has been started in Austria in patients recruited to a clinical trial, followed by its long-term extension and prescription treatment overall covering up to 10 years. In this case series the experience of treating Gaucher patients with eliglustat in Vienna is summarized. Patients were either switched from enzyme replacement therapy or were therapy naïve. Significant improvements were shown in hematological (thrombocytes, hemoglobin) and visceral (spleen volume) manifestations as well as in biomarkers (chitotriosidase, glucosylsphingosine [lyso-GL1], angiotensin converting enzyme) in a routine setting in a therapy-naïve patient. Stability was found in switch patients with slight improvement in bone density. Eliglustat was generally very well tolerated. Patient selection and regular monitoring is required to ensure effective and safe use.

An Unexpected Finding of Hepatosplenomegaly in a Pediatric Patient

Gaucher disease (GD) is a rare autosomal recessive metabolic disorder. It is characterized by a deficiency of lysosomal glucocerebrosidase, which results in the accumulation of glycosphingolipid substrates, primarily glucosylceramide, in the phagocyte system. In GD Type 1, the liver, spleen, and bone marrow are typically affected. We report the case of a 7-year-old female with GD Type 1 who presented with hepatosplenomegaly detected incidentally following a motor vehicle accident. She was found to have concomitant thrombocytopenia and Erlenmeyer flask deformities of her lower limbs. Diagnosis was made on the basis of very low leukocyte β-glucocerebrosidase activity and elevated plasma chitotriosidase. DNA mutation studies revealed both c.1226A>G and c.116_1505 deletion (exons 3-11). The patient is currently managed with biweekly intravenous imiglucerase (Cerezyme) replacement therapy. She demonstrated resolution of thrombocytopenia and hepatosplenomegaly at 2-year follow-up. Physicians must consider this rare diagnosis in children presenting with hepatosplenomegaly to prompt timely management.

Novel Management and Screening Approaches for Haematological Complications of Gaucher's Disease

Purpose

Gaucher disease (GD) is the most common lysosomal storage disorder. The principal manifestations for its diagnosis and further monitoring include haematological manifestations such as anaemia, thrombocytopaenia, spleen enlargement, and bleeding disorders, among others. This review aims to summarise and update the role of haematological complications in GD diagnosis and follow-up, describe their management strategies, and to use these indicators as part of the diagnostic approach.

Materials and Methods

A systematic review following the recommendations of PRISMA-P 2020 was carried out. Publications indexed in the databases PubMed, Embase, Science Open, Mendeley, and Web of Science were electronically searched by three independent reviewers, and publications up to June 2021 were accessed. A total of 246 publications were initially listed, of which 129 were included for further review and analysis. Case reports were considered if they were representative of a relevant hematologic complication.

Results

From the first review dated in 1974 to the latest publication in 2021, including different populations confirmed that the haematological manifestations such as thrombocytopaenia and splenomegaly at diagnosis of GD type 1 are the most frequent features of the disease. The incorporation of haematological parameters to diagnosis strategies increases their cost-effectiveness. Hematologic parameters are part of the scoring system for disease assessment and the evaluation of therapeutic outcomes, providing reliable and accessible data to improve the management of GD. However, cytopaenia, underlying coagulation disorders, and platelet dysfunction need to be addressed, especially during pregnancy or surgery. Long-term haematological complications include the risk of neoplasia and immune impairment, an area of unmet need that is currently under research.

Conclusion

Haematological features are key for GD suspicion, diagnosis, and management. Normalization of hematological parameters is achieved with the treatment; however, there are unmet needs such as the underlying inflammatory status and the long-term risk of hematologic neoplasia.

Glucocerebrosidase mutations: A paradigm for neurodegeneration pathways

Biallelic (homozygous or compound heterozygous) glucocerebrosidase gene (GBA) mutations cause Gaucher disease, whereas heterozygous mutations are numerically the most important genetic risk factor for Parkinson disease (PD) and are associated with the development of other synucleinopathies, notably Dementia with Lewy Bodies. This phenomenon is not limited to GBA, with converging evidence highlighting further examples of autosomal recessive disease genes increasing neurodegeneration risk in heterozygous mutation carriers. Nevertheless, despite extensive research, the cellular mechanisms by which mutations in GBA, encoding lysosomal enzyme β-glucocerebrosidase (GCase), predispose to neurodegeneration remain incompletely understood. Alpha-synuclein (A-SYN) accumulation, autophagic lysosomal dysfunction, mitochondrial abnormalities, ER stress and neuroinflammation have been proposed as candidate pathogenic pathways in GBA-linked PD. The observation of GCase and A-SYN interactions in PD initiated the development and evaluation of GCase-targeted therapeutics in PD clinical trials.

In-depth phenotyping for clinical stratification of Gaucher disease

BACKGROUND

The Gaucher Investigative Therapy Evaluation is a national clinical cohort of 250 patients aged 5-87 years with Gaucher disease in the United Kingdom-an ultra-rare genetic disorder. To inform clinical decision-making and improve pathophysiological understanding, we characterized the course of Gaucher disease and explored the influence of costly innovative medication and other interventions. Retrospective and prospective clinical, laboratory and radiological information including molecular analysis of the GBA1 gene and comprising > 2500 variables were collected systematically into a relational database with banking of collated biological samples in a central bioresource. Data for deep phenotyping and life-quality evaluation, including skeletal, visceral, haematological and neurological manifestations were recorded for a median of 17.3 years; the skeletal and neurological manifestations are the main focus of this study.

RESULTS

At baseline, 223 of the 250 patients were classified as type 1 Gaucher disease. Skeletal manifestations occurred in most patients in the cohort (131 of 201 specifically reported bone pain). Symptomatic osteonecrosis and fragility fractures occurred respectively in 76 and 37 of all 250 patients and the first osseous events occurred significantly earlier in those with neuronopathic disease. Intensive phenotyping in a subgroup of 40 patients originally considered to have only systemic features, revealed neurological involvement in 18: two had Parkinson disease and 16 had clinical signs compatible with neuronopathic Gaucher disease-indicating a greater than expected prevalence of neurological features. Analysis of longitudinal real-world data enabled Gaucher disease to be stratified with respect to advanced therapies and splenectomy. Splenectomy was associated with an increased hazard of fragility fractures, in addition to osteonecrosis and orthopaedic surgery; there were marked gender differences in fracture risk over time since splenectomy. Skeletal disease was a heavy burden of illness, especially where access to specific therapy was delayed and in patients requiring orthopaedic surgery.

CONCLUSION

Gaucher disease has been explored using real-world data obtained in an era of therapeutic transformation. Introduction of advanced therapies and repeated longitudinal measures enabled this heterogeneous condition to be stratified into obvious clinical endotypes. The study reveals diverse and changing phenotypic manifestations with systemic, skeletal and neurological disease as inter-related sources of disability.

Recalling the pathology of Parkinson's disease; lacking exact figure of prevalence and genetic evidence in Asia with an alarming outcome: A time to step-up

Parkinson's disease (PD) is the second most common and progressive neurodegenerative disease globally, with major symptoms like bradykinesia, impaired posture, and tremor. Several genetic and environmental factors have been identified but elucidating the main factors have been challenging due to the disease's complex nature. Diagnosis, prognosis, and management of such diseases are challenging and require effective targeted attention in developing countries. Recently, PD is growing rapidly in many crowded Asian countries as an alarming threat with inadequate knowledge of its prevalence, genetic architecture, and geographic distribution. This study gave an in-depth overview of the prevalence, incidence and genomic/genetics studies published so far in the Asian population. To the best of our knowledge, PD has increased significantly in several Asian countries, including China, South Korea, Japan, Thailand, and Israel over the past few years, requiring a greater level of care and attention. Genetic screening of families with PD at national levels and establishing an official database of PD cases are essential to get a comprehensive and conclusive view of the exact prevalence and genetic diversity of PD in the Asian population to properly manage and treat the disease.

Successful treatment of Gaucher disease type 1 by enzyme replacement therapy over a 10-year duration in a Japanese pediatric patient: A case report

The prevalence of Gaucher disease (GD) in Japan is much lower than that in Western countries; therefore, data on Japanese pediatric patients with GD type 1 are currently limited. The present study reports on the case of a Japanese pediatric patient with GD type 1 who was diagnosed when she presented with hepatosplenomegaly, thrombocytopenia and slight anemia at the age of 2 years. Serology tests revealed high levels of acid phosphatase (ACP) and angiotensin-converting enzyme (ACE). A bone marrow biopsy revealed the presence of Gaucher cells. Abdominal MRI indicated huge hepatosplenomegaly. Erlenmeyer flask deformity was observed on X-ray examination. MRI of the femora featured a high-intensity area within the diaphysis region. The enzymatic activity of leukocyte β-glucosidase, the measurement of which is necessary for a definitive diagnosis of GD, had decreased to 186.7 nmol/h/mg (reference range, 1,424.0-2,338.0 nmol/h/mg). Based on these results, the patient was clinically diagnosed with GD. Glucocerebrosidase gene analysis identified the compound heterozygote mutation of F213I (c.754T>A) on exon 7 and L444P (c.1448T>C) on exon 11. Enzyme replacement therapy (ERT) along with an intravenous infusion of 60 U/kg of imiglucerase every other week was initiated following diagnosis. Hemoglobin levels and the platelet count gradually improved and normalized after two years. ACP and ACE levels, biomarkers of the progression of GD, also improved. Abdominal MRI at six months after the initiation of ERT revealed a decrease in the size of the liver and spleen, which normalized after 1 year. Conversely, MRI of the femora indicated no improvement in the high-intensity area within the diaphysis region for 10 years.

Gaucher disease and SARS-CoV-2 infection: Experience from 181 patients in New York

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.

Serum progranulin levels in paediatric patients with Gaucher disease; relation to disease severity and liver stiffness by transient elastography

BACKGROUND

Non-invasive screening for liver fibrosis using transient elastography (TE) could be of value in the management of Gaucher disease (GD). Progranulin (PGRN) is a novel disease modifier in GD and an independent marker of liver fibrosis.

OBJECTIVES

We determined PGRN levels in paediatric patients with GD and assessed its role as a potential marker for disease severity and relation to liver stiffness by TE.

METHODS

Fifty-one GD patients (20 had type 1 and 31 had type 3) with a median age of 9.5 years were compared to 40 age- and sex-matched healthy controls and were studied focusing on visceral manifestations, neurological disease, haematological profile and PGRN levels as well as abdominal ultrasound and TE. Patients were on enzyme replacement therapy (ERT) for various durations and those with viral hepatitis infection were excluded.

RESULTS

By TE, 14 GD patients (27.5%) had elevated liver stiffness ≥7.0 kPa. Liver stiffness was significantly higher in type 1 GD patients than type 3 (P = .002), in splenectomized patients (P = .012) and those with dysphagia (P < .001). Liver stiffness was positively correlated with age of onset of ERT (P < .001). PGRN levels were significantly lower in GD patients compared with controls (P < .001). PGRN was significantly lower in GD patients with squint (P = .025), dysphagia (P = .036) and elevated liver stiffness (P = .015). PGRN was positively correlated with white blood cell count (r = .455, P = .002) and haemoglobin (r = .546, P < .001), while negatively correlated with severity score index (r = -.529, P < .001), liver volume (r = -.298, P = .034) and liver stiffness (r = -.652, P < .001).

CONCLUSIONS

Serum PGRN levels were associated with clinical disease severity and elevated liver stiffness in paediatric GD patients.

Fronto-temporal dementia risk gene TMEM106B has opposing effects in different lysosomal storage disorders

TMEM106B is a transmembrane protein localized to the endo-lysosomal compartment. Genome-wide association studies have identified TMEM106B as a risk modifier of Alzheimer's disease and frontotemporal lobar degeneration, especially with progranulin haploinsufficiency. We recently demonstrated that TMEM106B loss rescues progranulin null mouse phenotypes including lysosomal enzyme dysregulation, neurodegeneration and behavioural alterations. However, the reason whether TMEM106B is involved in other neurodegenerative lysosomal diseases is unknown. Here, we evaluate the potential role of TMEM106B in modifying the progression of lysosomal storage disorders using progranulin-independent models of Gaucher disease and neuronal ceroid lipofuscinosis. To study Gaucher disease, we employ a pharmacological approach using the inhibitor conduritol B epoxide in wild-type and hypomorphic Tmem106b-/- mice. TMEM106B depletion ameliorates neuronal degeneration and some behavioural abnormalities in the pharmacological model of Gaucher disease, similar to its effect on certain progranulin null phenotypes. In order to examine the role of TMEM106B in neuronal ceroid lipofuscinosis, we crossbred Tmem106b-/- mice with Ppt1-/-, a genetic model of the disease. In contrast to its conduritol B epoxide-rescuing effect, TMEM106B loss exacerbates Purkinje cell degeneration and motor deficits in Ppt1-/- mice. Mechanistically, TMEM106B is known to interact with subunits of the vacuolar ATPase and influence lysosomal acidification. In the pharmacological Gaucher disease model, the acidified lysosomal compartment is enhanced and TMEM106B loss rescues in vivo phenotypes. In contrast, gene-edited neuronal loss of Ppt1 causes a reduction in vacuolar ATPase levels and impairment of the acidified lysosomal compartment, and TMEM106B deletion exacerbates the mouse Ppt1-/- phenotype. Our findings indicate that TMEM106B differentially modulates the progression of the lysosomal storage disorders Gaucher disease and neuronal ceroid lipofuscinosis. The effect of TMEM106B in neurodegeneration varies depending on vacuolar ATPase state and modulation of lysosomal pH. These data suggest TMEM106B as a target for correcting lysosomal pH alterations, and in particular for therapeutic intervention in Gaucher disease and neuronal ceroid lipofuscinosis.

Sphingolipids metabolism alteration in the central nervous system: Amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases

Sphingolipids are complex lipids. They play a structural role in neurons, but are also involved in regulating cellular communication, and neuronal differentiation and maturation. There is increasing evidence to suggest that dysregulated metabolism of sphingolipids is linked to neurodegenerative processes in amyotrophic lateral sclerosis (ALS), Parkinson's disease and Gaucher's disease. In this review, we provide an overview of the role of sphingolipids in the development and maintenance of the nervous system. We describe the implications of altered metabolism of sphingolipids in the pathophysiology of certain neurodegenerative diseases, with a primary focus on ALS. Finally, we provide an update of potential treatments that could be used to target the metabolism of sphingolipids in neurodegenerative diseases.

Allogeneic hematopoietic stem cell transplantation for treating severe lung involvement in Gaucher disease

Objective

To provide strategies for monitoring and treating severe lung involvement in Gaucher disease.

Study design

We reviewed the chart of a 5-year-old boy who developed rapidly progressive, severe infiltrative lung involvement of Gaucher disease (GD) and improved after allogeneic hematopoietic stem cell transplant (HSCT), along with other case studies reported before December 2019. He was diagnosed with GD (homozygous mutation at c.1448 T > C, p.L483P), and started receiving enzyme replacement therapy (ERT) at 17 months old. He developed respiratory distress symptoms after 45 months of ERT; chest imaging reported diffuse interstitial infiltration of the bilateral lungs and consolidations at the right lungs. Allogeneic HSCT using cells from a matched unrelated donor was performed four months upon progressive respiratory symptoms.

Results

His respiratory symptoms subsided in one month; chest imaging improvement, pulmonary function test improvement, and normalized activity of β-glucocerebrosidase were reported in three months.

Conclusion

This is the first report of a patient who received early and regular ERT but developed severe infiltrative lung involvement and recovered after allogeneic HSCT. Based on study results, we suggest regular chest imaging, even for asymptomatic patients. For patients with severe lung involvement, rapid deterioration, and unresponsive to higher ERT dosages, allogeneic HSCT should be considered.

Identification of risk features for complication in Gaucher's disease patients: a machine learning analysis of the Spanish registry of Gaucher disease

BACKGROUND

Since enzyme replacement therapy for Gaucher disease (MIM#230800) has become available, both awareness of and the natural history of the disease have changed. However, there remain unmet needs such as the identification of patients at risk of developing bone crisis during therapy and late complications such as cancer or parkinsonism. The Spanish Gaucher Disease Registry has worked since 1993 to compile demographic, clinical, genetic, analytical, imaging and follow-up data from more than 400 patients. The aims of this study were to discover correlations between patients' characteristics at diagnosis and to identify risk features for the development of late complications; for this a machine learning approach involving correlation networks and decision trees analyses was applied.

RESULTS

A total of 358 patients, 340 type 1 Gaucher disease and 18 type 3 cases were selected. 18% were splenectomyzed and 39% had advanced bone disease. 81% of cases carried heterozygous genotype. 47% of them were diagnosed before the year 2000. Mean age at diagnosis and therapy were 28 and 31.5 years old (y.o.) respectively. 4% developed monoclonal gammopathy undetermined significance or Parkinson Disease, 6% cancer, and 10% died before this study. Previous splenectomy correlates with the development of skeletal complications and severe bone disease (p = 0.005); serum levels of IgA, delayed age at start therapy (> 9.5 y.o. since diagnosis) also correlates with severe bone disease at diagnosis and with the incidence of bone crisis during therapy. High IgG (> 1750 mg/dL) levels and age over 60 y.o. at diagnosis were found to be related with the development of cancer. When modelling the decision tree, patients with a delayed diagnosis and therapy were the most severe and with higher risk of complications.

CONCLUSIONS

Our work confirms previous observations, highlights the importance of early diagnosis and therapy and identifies new risk features such as high IgA and IgG levels for long-term complications.

Neurochemical abnormalities in patients with type 1 Gaucher disease on standard of care therapy

Type 1 Gaucher disease (GD1), a glycosphingolipid storage disorder caused by deficient activity of lysosomal glucocerebrosidase, is classically considered non-neuronopathic. However, current evidence challenges this view. Multiple studies show that mutations in GBA1 gene and decreased glucocerebrosidase activity are associated with increased risk for Parkinson disease. We tested the hypothesis that subjects with GD1 will show neurochemical abnormalities consistent with cerebral involvement. We performed Magnetic Resonance Spectroscopy at 7 T to quantify neurochemical profiles in participants with GD1 (n = 12) who are on stable therapy. Age and gender matched healthy participants served as controls (n = 13). Neurochemical profiles were obtained from parietal white matter (PWM), posterior cingulate cortex (PCC), and putamen. Further, in the GD1 group, the neurochemical profiles were compared between individuals with and without a single L444P allele. We observed significantly lower levels of key neuronal markers, N-acetylaspartate, γ-aminobutyric acid, glutamate and glutamate-to-glutamine ratio in PCC of participants with GD1 compared to healthy controls (P < .015). Glutamate concentration was also lower in the putamen in GD1 (P = .01). Glucose + taurine concentration was significantly higher in PWM (P = .04). Interestingly, individuals without L444P had significantly lower aspartate and N-acetylaspartylglutamate in PCC (both P < .001), although this group was 7 years younger than those with an L444P allele. This study demonstrates neurochemical abnormalities in individuals with GD1, for which clinical and prognostic significance remains to be determined. Further studies in a larger cohort are required to confirm an association of neurochemical levels with mutation status and glucocerebrosidase structure and function. SYNOPSIS: Ultrahigh field magnetic resonance spectroscopy reveals abnormalities in neurochemical profiles in patients with GD1 compared to matched healthy controls.

Polyneuropathy in Gaucher disease type 1 and 3 - a descriptive case series

Polyneuropathy (PNP) has been reported to be a possible phenotypic feature in Gaucher disease type 1 (GD1), while less is known about PNP in type 3 (GD3). We performed a cross-sectional study, exploring PNP in a Swedish GD cohort. Clinical assessment and blood biochemistry were carried out in 8 patients with GD1 and 11 patients with GD3. In patients with symptoms or clinical findings indicative of PNP, nerve conduction studies and quantitative sensory testing were performed. Assessments were compared to historic controls. A subclinical small fiber neuropathy (SFN) was demonstrated in 2 of 8 patients in the significantly (p = 0,021) older GD1 cohort. A large fiber PNP was evident in an additional 3 GD1 patients but could not be ascribed as disease manifestation. No GD3 patients exhibited neurophysiological evidence of small or large fiber PNP attributed to GD3. Compared to historic controls, no significant group differences were evident with regard to neuropathy rating scores. In summary, our study does not support large fiber PNP as a prevalent manifestation of GD. SFN is a possible feature in GD1, although small sample size limits definite conclusions. Our study provides novel data, arguing against clinically significant small or large fiber PNP in GD3.

Ophthalmic manifestations of Gaucher disease: the most common lysosomal storage disorder

Gaucher disease (GD) results from a deficiency of glucocerebrosidase activity and the subsequent accumulation of the enzyme's metabolites, principally glucosylsphingosine and glucosylceramide. There are three principal forms: Type I, which is the most common, is usually considered non-neuronopathic. Type II, III and IIIc manifest earlier and have neurological sequelae due to markedly reduced enzyme activity. Gaucher's can be associated with ophthalmological sequelae but these have not been systematically reviewed. We therefore performed a comprehensive literature review of all such ophthalmic abnormalities associated with the different types of Gaucher disease. We systematically searched the literature (1950 - present) for functional and structural ocular abnormalities arising in patients with Gaucher disease and found that all subtypes can be associated with ophthalmic abnormalities; these range from recently described intraocular lesions to disease involving the adnexae, peripheral nerves and brain. In summary, Gaucher can affect most parts of the eye. Rarely is it sight-threatening; some but not all manifestations are amenable to treatment, including with enzyme replacement and substrate reduction therapy. Retinal involvement is rare but patients with ocular manifestations should be monitored and treated early to reduce the risk of progression and further complications. As Gaucher disease is also associated with Parkinsons disease and may also confer an increased risk of malignancy (particularly haematological forms and melanoma), any ocular abnormalities should be fully investigated to exclude these potential underlying conditions.

Gaucher disease iPSC-derived osteoblasts have developmental and lysosomal defects that impair bone matrix deposition

Gaucher disease (GD) is caused by bi-allelic mutations in GBA1, the gene that encodes acid β-glucocerebrosidase (GCase). Individuals affected by GD have hematologic, visceral and bone abnormalities, and in severe cases there is also neurodegeneration. To shed light on the mechanisms by which mutant GBA1 causes bone disease, we examined the ability of human induced pluripotent stem cells (iPSC) derived from patients with Types 1, 2 and 3 GD, to differentiate to osteoblasts and carry out bone deposition. Differentiation of GD iPSC to osteoblasts revealed that these cells had developmental defects and lysosomal abnormalities that interfered with bone matrix deposition. Compared with controls, GD iPSC-derived osteoblasts exhibited reduced expression of osteoblast differentiation markers, and bone matrix protein and mineral deposition were defective. Concomitantly, canonical Wnt/β catenin signaling in the mutant osteoblasts was downregulated, whereas pharmacological Wnt activation with the GSK3β inhibitor CHIR99021 rescued GD osteoblast differentiation and bone matrix deposition. Importantly, incubation with recombinant GCase (rGCase) rescued the differentiation and bone-forming ability of GD osteoblasts, demonstrating that the abnormal GD phenotype was caused by GCase deficiency. GD osteoblasts were also defective in their ability to carry out Ca2+-dependent exocytosis, a lysosomal function that is necessary for bone matrix deposition. We conclude that normal GCase enzymatic activity is required for the differentiation and bone-forming activity of osteoblasts. Furthermore, the rescue of bone matrix deposition by pharmacological activation of Wnt/β catenin in GD osteoblasts uncovers a new therapeutic target for the treatment of bone abnormalities in GD.

A novel mutation causing type 1 Gaucher disease found in a Japanese patient with gastric cancer: A case report

RATIONALE

Gaucher disease (GD) is an autosomal recessive disorder that leads to multiorgan complications caused by β-glucocerebrosidase deficiency due to mutations in the β-glucocerebrosidase-encoding gene (GBA). GD morbidity in Japan is quite rare and clinical phenotype and gene mutation patterns of patients with GD in Japan and Western countries differ considerably. Of Japanese patients with GD, 57% develop types 2 or 3 GD with neurologic manifestations and younger onset, whereas only 6% of patients with GD develop those manifestations in Western countries. Thus, it is relatively difficult to find and diagnose GD in Japan.

PATIENT CONCERNS

A 69-year-old Japanese female with mild anemia and thrombocytopenia but without neurologic symptoms was initially referred for gastric cancer. Preoperative F-deoxyglucose positron emission tomography/computed tomography (FDG PET/CT) showed accumulation in the bone marrow and paraabdominal lymph nodes. Following bone marrow aspiration found, abnormal foamy macrophages in the bone marrow and electron microscopy revealed that the macrophages were filled with tubular-form structures. Adding to these signs suggestive of a lysosomal disease, serum β-glucocerebrosidase activity test found decreased. Sequencing of the patient's GBA gene revealed a RecNciI recombinant mutation and the novel mutation K157R (c.587A>G).

DIAGNOSES

On the basis of these findings and clinical manifestations, the final diagnosis of type 1 GD was made.

INTERVENTIONS

Enzyme replacement therapy (ERT) with velaglucerase α was started after the diagnosis of type 1 GD.

OUTCOMES

The patient's β-glucocerebrosidase activity as well as hemoglobin and platelet levels were restored by ERT without any side effects. Bone marrow aspirations 10 months after the start of the treatment with velaglucerase α showed reduction of Gaucher cells in bone marrow to 2% from 4% of total cellularity.

LESSONS

This is the first report of F-FDG PET/CT application providing a clue for GD diagnosis. A novel mutation in GBA is described, which implies a potential pool of patients with GD with this mutation in Japan.

Diagnosis and Management of Gaucher Disease in India – Consensus Guidelines of the Gaucher Disease Task Force of the Society for Indian Academy of Medical Genetics and the Indian Academy of Pediatrics

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 β-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.

Corrective surgery for kyphosis in a case of Gaucher's disease without history of vertebral compression fractures

Introduction

Gaucher's disease is a congenital metabolic disorder characterized by the accumulation of glucocerebroside in the reticuloendothelial system. Its clinical manifestations include splenomegaly, osteopenia, and pathological fractures. Cases of patients with kyphotic deformities caused by pathological vertebral compression fractures associated with Gaucher's disease are well reported. However, there has been no report regarding surgical treatment of kyphotic deformity caused by Gaucher's disease without compression fractures. In the present report, we describe surgical treatment for kyphotic deformity caused by Gaucher's disease without a past history of vertebral compression fractures.

Case Report

The patient was diagnosed with Gaucher's disease at the age of 15 months. The patient was a 10-year-old girl with progressive kyphosis (84° between T6 and L3, with T12 as the apical vertebra) without compression fractures. Although the patient had been treated using a brace since the age of 3 years, the kyphosis progressed to the point where corrective surgery was required. We initially performed T3-L3 posterior spinal fusion, followed by anterior fusion 3 months later, which corrected the kyphosis to 35°. Postoperatively, the patient suffered fractures of the upper and lower extremities but did not have spinal fractures.

Conclusions

Two-stage anterior/posterior combined correction and fusion was performed in a patient with kyphotic deformity caused by Gaucher's disease without compression fractures. Because of bone fragility in Gaucher's disease, careful selection of the fusion range and postoperative therapy was necessary.

Lipid Involvement in Neurodegenerative Diseases of the Motor System: Insights from Lysosomal Storage Diseases

Lysosomal storage diseases (LSDs) are a heterogeneous group of rare inherited metabolic diseases that are frequently triggered by the accumulation of lipids inside organelles of the endosomal-autophagic-lysosomal system (EALS). There is now a growing realization that disrupted lysosomal homeostasis (i.e., lysosomal cacostasis) also contributes to more common neurodegenerative disorders such as Parkinson disease (PD). Lipid deposition within the EALS may also participate in the pathogenesis of some additional neurodegenerative diseases of the motor system. Here, I will highlight the lipid abnormalities and clinical manifestations that are common to LSDs and several diseases of the motor system, including amyotrophic lateral sclerosis (ALS), atypical forms of spinal muscular atrophy, Charcot-Marie-Tooth disease (CMT), hereditary spastic paraplegia (HSP), multiple system atrophy (MSA), PD and spinocerebellar ataxia (SCA). Elucidating the underlying basis of intracellular lipid mislocalization as well as its consequences in each of these disorders will likely provide innovative targets for therapeutic research.

A multicenter, open-label, phase III study of Abcertin in Gaucher disease

BACKGROUND

Gaucher disease (GD) is caused by a deficiency in the lysosomal enzyme glucocerebrosidase. Enzyme replacement therapy (ERT) is recommended for clinical improvement.

METHODS

The efficacy and safety of a new imiglucerase, Abcertin, were assessed in 7 Egyptian patients with treatment-naïve type 1 GD. Each patient was administered a biweekly 60 U/kg dose of Abcertin for 6 months. The primary endpoint was the change in hemoglobin concentration. The secondary endpoints were changes from baseline in platelet counts, spleen and liver volumes, biomarker levels, skeletal parameters, and bone mineral density.

RESULTS

The hemoglobin concentration increased by a mean of 1.96 ± 0.91 g/dL (range 1.11-2.80 g/dL) or 20.6% (P = .001). Statistically significant increases in the platelet count and decreases in the spleen volume and biomarker levels were also observed. There were no severe drug-related adverse events. One patient developed anti-imiglucerase antibodies without neutralizing activity.

CONCLUSION

Our study results demonstrate the efficacy and safety of Abcertin in patients with type 1 GD. This suggests that Abcertin can be an alternative ERT option for type 1 GD.

Glucosylceramide and Glucosylsphingosine Quantitation by Liquid Chromatography-Tandem Mass Spectrometry to Enable In Vivo Preclinical Studies of Neuronopathic Gaucher Disease

Gaucher disease (GD) is caused by mutations in the GBA1 gene that encodes the lysosomal enzyme acid β-glucosidase (GCase). Reduced GCase activity primarily leads to the accumulation of two substrates, glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph). Current treatment options have not been shown to ameliorate the neurological pathology observed in the most severe forms of GD, clearly representing an unmet medical need. To better understand the relationship between GlcCer and GlcSph accumulation and ultimately their connection with the progression of neurological pathology, we developed LC-MS/MS methods to quantify GlcCer and GlcSph in mouse brain tissue. A significant challenge in developing these methods was the chromatographic separation of GlcCer and GlcSph from the far more abundant isobaric galactosyl epimers naturally occurring in white matter. After validation of both methods, we evaluated the levels of both substrates in five different GD mouse models, and found significant elevation of brain GlcSph in all five, while GlcCer was elevated in only one of the five models. In addition, we measured GlcCer and GlcSph levels in the brains of wild-type mice after administration of the GCase inhibitor conduritol β-epoxide (CBE), as well as the nonlysosomal β-glucosidase (GBA2) inhibitor N-butyldeoxygalactonojirimycin (NB-DGJ). Inhibition of GCase by CBE resulted in elevation of both sphingolipids; however, inhibition of GBA2 by NB-DGJ resulted in elevation of GlcCer only. Taken together, these data support the idea that GlcSph is a more selective and sensitive biomarker than GlcCer for neuronopathic GD in preclinical models.

A comparison study of bioanalytical methods for detection and characterization of anti-velaglucerase alfa antibodies

AIM

To provide more efficient and timely immunogenicity testing service to support routine patient care, the original complex testing algorithm for evaluation of anti-velaglucerase alfa antibodies has been simplified and individual methods (screen, confirm, titer, neutralizing antibody [NAb] and IgE) have been redeveloped/optimized and validated.

RESULTS

To compare the performance of different methods, 50 velaglucerase alfa-treated patient samples were analyzed using both old and new methods for the presence of antidrug antibodies (ADAs) and 31 ADA-positive samples were analyzed for neutralizing capacity. The ADA and NAb statuses are almost identical from both methods and both ADA and NAb titer results are highly correlated with a Spearman's correlation of 0.96 and 0.86, respectively.

CONCLUSION

The original and new testing methods can be considered interchangeable for the measurement of total and neutralizing anti-velaglucerase alfa antibodies.

Investigations on therapeutic glucocerebrosidases through paired detection with fluorescent activity-based probes

Deficiency of glucocerebrosidase (GBA) causes Gaucher disease (GD). In the common non-neuronopathic GD type I variant, glucosylceramide accumulates primarily in the lysosomes of visceral macrophages. Supplementing storage cells with lacking enzyme is accomplished via chronic intravenous administration of recombinant GBA containing mannose-terminated N-linked glycans, mediating the selective uptake by macrophages expressing mannose-binding lectin(s). Two recombinant GBA preparations with distinct N-linked glycans are registered in Europe for treatment of type I GD: imiglucerase (Genzyme), contains predominantly Man(3) glycans, and velaglucerase (Shire PLC) Man(9) glycans. Activity-based probes (ABPs) enable fluorescent labeling of recombinant GBA preparations through their covalent attachment to the catalytic nucleophile E340 of GBA. We comparatively studied binding and uptake of ABP-labeled imiglucerase and velaglucerase in isolated dendritic cells, cultured human macrophages and living mice, through simultaneous detection of different GBAs by paired measurements. Uptake of ABP-labeled rGBAs by dendritic cells was comparable, as well as the bio-distribution following equimolar intravenous administration to mice. ABP-labeled rGBAs were recovered largely in liver, white-blood cells, bone marrow and spleen. Lungs, brain and skin, affected tissues in severe GD types II and III, were only poorly supplemented. Small, but significant differences were noted in binding and uptake of rGBAs in cultured human macrophages, in the absence and presence of mannan. Mannan-competed binding and uptake were largest for velaglucerase, when determined with single enzymes or as equimolar mixtures of both enzymes. Vice versa, imiglucerase showed more prominent binding and uptake not competed by mannan. Uptake of recombinant GBAs by cultured macrophages seems to involve multiple receptors, including several mannose-binding lectins. Differences among cells from different donors (n = 12) were noted, but the same trends were always observed. Our study suggests that further insight in targeting and efficacy of enzyme therapy of individual Gaucher patients could be obtained by the use of recombinant GBA, trace-labeled with an ABP, preferably equipped with an infrared fluorophore or other reporter tag suitable for in vivo imaging.

Elevation of glycoprotein nonmetastatic melanoma protein B in type 1 Gaucher disease patients and mouse models

Gaucher disease is caused by inherited deficiency of lysosomal glucocerebrosidase. Proteome analysis of laser‐dissected splenic Gaucher cells revealed increased amounts of glycoprotein nonmetastatic melanoma protein B (gpNMB). Plasma gpNMB was also elevated, correlating with chitotriosidase and CCL18, which are established markers for human Gaucher cells. In Gaucher mice, gpNMB is also produced by Gaucher cells. Correction of glucocerebrosidase deficiency in mice by gene transfer or pharmacological substrate reduction reverses gpNMB abnormalities. In conclusion, gpNMB acts as a marker for glucosylceramide‐laden macrophages in man and mouse and gpNMB should be considered as candidate biomarker for Gaucher disease in treatment monitoring.

Varied autopsy findings in five treated patients with Gaucher disease and parkinsonism include the absence of Gaucher cells

Enzyme replacement therapy is standard of care for patients with Gaucher disease, as it significantly improves skeletal, visceral, and hematological symptoms. Few pathological studies have documented the extent of pathological findings in treated patients. Autopsy findings in five treated patients, who ultimately developed parkinsonism, ranged from the complete absence of Gaucher pathology to extensive involvement of multiple tissues, without correlation to age, genotype, spleen status, or dose/duration of therapy. Additional autopsies may elucidate modifiers and biomarkers contributing to disease burden and response to therapy.

The relationship between glucocerebrosidase mutations and Parkinson disease

Parkinson disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease, whereas Gaucher disease (GD) is the most frequent lysosomal storage disorder caused by homozygous mutations in the glucocerebrosidase (GBA1) gene. Increased risk of developing PD has been observed in both GD patients and carriers. It has been estimated that GBA1 mutations confer a 20‐ to 30‐fold increased risk for the development of PD, and that at least 7–10% of PD patients have a GBA1 mutation. To date, mutations in the GBA1 gene constitute numerically the most important risk factor for PD. The type of PD associated with GBA1 mutations (PD‐GBA1) is almost identical to idiopathic PD, except for a slightly younger age of onset and a tendency to more cognitive impairment. Importantly, the pathology of PD‐GBA1 is identical to idiopathic PD, with nigral dopamine cell loss, Lewy bodies, and neurites containing alpha‐synuclein. The mechanism by which GBA1 mutations increase the risk for PD is still unknown. However, given that clinical manifestation and pathological findings in PD‐GBA1 patients are almost identical to those in idiopathic PD individuals, it is likely that, as in idiopathic PD, alpha‐synuclein accumulation, mitochondrial dysfunction, autophagic impairment, oxidative and endoplasmic reticulum stress may contribute to the development and progression of PD‐GBA1. Here, we review the GBA1 gene, its role in GD, and its link with PD.

The impact of glucocerebrosidase 1 (GBA1) mutations on functioning of endoplasmic reticulum (ER), lysosomes, and mitochondria. GBA1 mutations resulting in production of misfolded glucocerebrosidase (GCase) significantly affect the ER functioning. Misfolded GCase trapped in the ER leads to both an increase in the ubiquitin–proteasome system (UPS) and the ER stress. The presence of ER stress triggers the unfolded protein response (UPR) and/or endoplasmic reticulum‐associated degradation (ERAD). The prolonged activation of UPR and ERAD subsequently leads to increased apoptosis. The presence of misfolded GCase in the lysosomes together with a reduction in wild‐type GCase levels lead to a retardation of alpha‐synuclein degradation via chaperone‐mediated autophagy (CMA), which subsequently results in alpha‐synuclein accumulation and aggregation. Impaired lysosomal functioning also causes a decrease in the clearance of autophagosomes, and so their accumulation. GBA1 mutations perturb normal mitochondria functioning by increasing generation of free radical species (ROS) and decreasing adenosine triphosphate (ATP) production, oxygen consumption, and membrane potential. GBA1 mutations also lead to accumulation of dysfunctional and fragmented mitochondria.

This article is part of a special issue on Parkinson disease.

Role of Ceramide from Glycosphingolipids and Its Metabolites in Immunological and Inflammatory Responses in Humans

Glycosphingolipids (GSLs) are composed of hydrophobic ceramide and hydrophilic sugar chains. GSLs cluster to form membrane microdomains (lipid rafts) on plasma membranes, along with several kinds of transducer molecules, including Src family kinases and small G proteins. However, GSL-mediated biological functions remain unclear. Lactosylceramide (LacCer, CDw17) is highly expressed on the plasma membranes of human phagocytes and mediates several immunological and inflammatory reactions, including phagocytosis, chemotaxis, and superoxide generation. LacCer forms membrane microdomains with the Src family tyrosine kinase Lyn and the Gαi subunit of heterotrimeric G proteins. The very long fatty acids C24:0 and C24:1 are the main ceramide components of LacCer in neutrophil plasma membranes and are directly connected with the fatty acids of Lyn and Gαi. These observations suggest that the very long fatty acid chains of ceramide are critical for GSL-mediated outside-in signaling. Sphingosine is another component of ceramide, with the hydrolysis of ceramide by ceramidase producing sphingosine and fatty acids. Sphingosine is phosphorylated by sphingosine kinase to sphingosine-1-phosphate, which is involved in a wide range of cellular functions, including growth, differentiation, survival, chemotaxis, angiogenesis, and embryogenesis, in various types of cells. This review describes the role of ceramide moiety of GSLs and its metabolites in immunological and inflammatory reactions in human.

Mechanism-based inhibitors of glycosidases: design and applications

This article covers recent developments in the design and application of activity-based probes (ABPs) for glycosidases, with emphasis on the different enzymes involved in metabolism of glucosylceramide in humans. Described are the various catalytic reaction mechanisms employed by inverting and retaining glycosidases. An understanding of catalysis at the molecular level has stimulated the design of different types of ABPs for glycosidases. Such compounds range from (1) transition-state mimics tagged with reactive moieties, which associate with the target active site—forming covalent bonds in a relatively nonspecific manner in or near the catalytic pocket—to (2) enzyme substrates that exploit the catalytic mechanism of retaining glycosidase targets to release a highly reactive species within the active site of the enzyme, to (3) probes based on mechanism-based, covalent, and irreversible glycosidase inhibitors. Some applications in biochemical and biological research of the activity-based glycosidase probes are discussed, including specific quantitative visualization of active enzyme molecules in vitro and in vivo, and as strategies for unambiguously identifying catalytic residues in glycosidases in vitro.

Switching from imiglucerase to miglustat for the treatment of French patients with Gaucher disease type 1: a case series

Introduction

Gaucher disease is caused by a deficiency of the enzyme β-glucocerebrosidase. Treatment with enzyme replacement therapy has been available for the past two decades but, although effective, enzyme replacement therapy can be delivered only by intravenous infusion every other week. The oral substrate reduction therapy miglustat (Zavesca®) has been available in Europe since 2002 for the treatment of patients with mild or moderate Gaucher disease type 1 for whom enzyme replacement therapy is unsuitable or not a therapeutic option. There are few published real-world data on the use of miglustat as a maintenance therapy in Gaucher disease type 1 patients switched from previous enzyme replacement therapy. We report a case series of three patients who were switched from long-term enzyme replacement therapy to miglustat for various reasons.

Case presentation

All three patients were Caucasian and had confirmed Gaucher disease type 1. An 80-year-old man requested a switch to oral miglustat therapy in preference to ongoing intravenous enzyme replacement therapy, a 57-year-old woman was commenced on miglustat due to a shortage of imiglucerase, and a 56-year-old woman was switched from previous enzyme replacement therapy due to allergic reactions to intravenous infusions. Hematological disease parameters were stable in each patient on previous enzyme replacement therapy. Two patients continue to be treated with miglustat, having shown good tolerability and stable core disease parameters for approximately 4 years. One patient, who was also stable during 7 years of therapy, eventually discontinued miglustat as a precaution because he developed peripheral neuropathy of as yet unknown origin.

Conclusions

Overall, our experience indicates that miglustat can be used as maintenance therapy for Gaucher disease type 1 after initial enzyme replacement therapy, but the selection of patients to whom this approach should be applied should be made after careful consideration of all disease parameters.

A phase 2 multi-center, open-label, switch-over trial to evaluate the safety and efficacy of Abcertin® in patients with type 1 Gaucher disease

Gaucher disease is a lysosomal storage disease for which enzyme replacement therapy has proven to be effective. A switch-over clinical trial was performed to evaluate the efficacy and safety of Abcertin® (ISU Abxis, Seoul, Korea) in subjects with type 1 Gaucher disease who were previously treated with imiglucerase. Five Korean patients with type 1 Gaucher disease were enrolled. Previous doses of imiglucerase ranged from 30 to 55 U/kg every other week. The same dose of Abcertin® was administered to all patients for 24 weeks. Primary efficacy endpoints were changes in hemoglobin levels and platelet counts, and the secondary efficacy endpoints included changes in liver and spleen volumes, serum biomarkers, skeletal status and bone mineral density (BMD). During the study period, no statistically significant changes were observed in all parameters including hemoglobin levels and platelet counts, liver and spleen volumes, skeletal status and BMD. Abcertin® administration was continued in three patients for another 24 weeks as an extension of the study. Hemoglobin levels and platelet counts were maintained in all three patients. In conclusion, the efficacy and safety of Abcertin® are similar to those of imiglucerase, and Abcertin® is an effective therapeutic agent for patients with type 1 Gaucher disease (Clinical Trial Registry No. NCT02053896 at www.clinicaltrials.gov).

Innovative treatments for lysosomal diseases

Striking therapeutic advances for lysosomal diseases have harnessed the biology of this organelle and illustrate its central rôle in the dynamic economy of the cell. Further Innovation will require improved protein-targetting or realization of therapeutic gene- and cell transfer stratagems. Rescuing function before irreversible injury, mandates a deep knowledge of clinical behaviour as well as molecular pathology – and frequently requires an understanding of neuropathology. Whether addressing primary causes, or rebalancing the effects of disordered cell function, true therapeutic innovation depends on continuing scientific exploration of the lysosome. Genuine partnerships between biotech and the patients affected by this extraordinary family of disorders continue to drive productive pharmaceutical discovery.