Osteopenia in Gaucher disease develops early in life: response to imiglucerase enzyme therapy in children, adolescents and adults

The Diagnosis and Therapy of Osteoporosis in Gaucher Disease

Gaucher disease is a rare lysosomal storage disorder characterized by the accumulation of glucocerebroside lipids within multiple organs due to a deficiency of the lysosomal enzyme (acid β-glucosidase). It is an inherited autosomal recessive disease. The onset of symptoms can vary depending on disease type and severity, with milder forms presenting in adulthood. The main clinical manifestations include cytopenia, splenomegaly, hepatomegaly, and bone lesions. GD is characterized by several bone manifestations, such as osteopenia/osteoporosis, focal lytic or sclerotic lesions, osteonecrosis acute or chronic bone pain, Erlenmeyer flask deformity, and subchondral joint collapse with secondary degenerative arthritis. In 70-100% of patients affected by Gaucher disease type 1, clinical or radiographic evidence of bone disease occurs. Among bone complications, osteoporosis is very common, but its etiopathogenesis in GD is not completely clear. Results deriving from experimental studies support the hypothesis that there is an aberrant activity of both osteoclasts and osteoblasts due to several factors, resulting in impaired bone turnover. Bone complications represent the main cause of pain, disability, and reduced quality of life in these patients. Therefore, there is a need to enhance awareness among physicians on the skeletal manifestations throughout life of GD patients, in order to improve diagnosis and management of bone complications. In particular, this narrative review focuses on risk of bone fragility in GD, etiopathogenetic hypotheses, epidemiological data, diagnosis, monitoring, and treatment of osteoporosis in patients suffering from Gaucher disease, specifying the challenges not yet addressed.

A Case of Gaucher Disease With Atypical Presentation Mimicking Chronic Recurrent Multifocal Osteomyelitis

We present the case of a nine-year-old male who presented with recurrent bony pain episodes since the age of four, requiring multiple hospital admissions. Initial workup showed anemia, thrombocytopenia, prolonged prothrombin time (PT), partial thromboplastin time (PTT), and elevated C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). The patient underwent an open biopsy of the right femur with irrigation and debridement that was inconclusive, but cultures were positive for methicillin-resistant Staphylococcus aureus (MRSA) and group G hemolytic streptococci that were treated with clindamycin. Differential diagnosis was broad with a negative workup for malignancy, chronic granulomatous disease, infectious causes, sarcoidosis, and vasculitis. Multiple MRIs were consistent with bilateral femur osteomyelitis, right proximal tibia, and right humerus osteomyelitis with negative cultures on subsequent admissions. The patient was diagnosed with chronic recurrent multifocal osteomyelitis (CRMO). He had clinical and laboratory improvement for two years on methotrexate. He was then tried on a short course of steroids and adalimumab for worsening symptoms. Bone biopsy was repeated, and findings were consistent with Gaucher disease (GD), which was confirmed on biochemical testing with low beta-glucosidase activity. He was started on enzyme replacement therapy with clinical and biochemical improvement.

Adult type I Gaucher disease with splenectomy caused by a compound heterozygous GBA1 mutation in a Chinese patient: a case report

Gaucher disease (GD) is an autosomal recessive ailment resulting from glucocerebrosidase deficiency caused by a mutation in the GBA1 gene, leading to multi-organ problems in the liver, spleen, and bone marrow. In China, GD is extremely uncommon and has a lower incidence rate than worldwide. In this study, we report the case of an adult male with an enlarged spleen for 13 years who presented with abdominal distension, severe loss of appetite and weight, reduction of the three-line due to hypersplenism, frequent nosebleeds, and bloody stools. Regrettably, the unexpected discovery of splenic pathology suggestive of splenic Gaucher disease was only made after a splenectomy due to a lack of knowledge about rare disorders. Our patient's delayed diagnosis may have been due to the department where he was originally treated, but it highlights the need for multidisciplinary consultation in splenomegaly of unknown etiology. We then investigated the patient's clinical phenotypes and gene mutation features using genetically phenotypical analysis. The analysis of the GBA1 gene sequence indicated that the patient carried a compound heterozygous mutation consisting of two potentially disease-causing mutations: c.907C > A (p. Leu303Ile) and c.1448 T > C (p. Leu483Pro). While previous research has linked the p. Leu483Pro mutation site to neurologic GD phenotypes (GD2 and GD3), the patients in this investigation were identified as having non-neuronopathic GD1. The other mutation, p. Leu303Ile, is a new GD-related mutation not indexed in PubMed that enriches the GBA1 gene mutation spectrum. Biosignature analysis has shown that both mutations alter the protein's three-dimensional structure, which may be a pathogenic mechanism for GD1 in this patient.

Sphingolipid-Induced Bone Regulation and Its Emerging Role in Dysfunction Due to Disease and Infection

The human skeleton is a metabolically active system that is constantly regenerating via the tightly regulated and highly coordinated processes of bone resorption and formation. Emerging evidence reveals fascinating new insights into the role of sphingolipids, including sphingomyelin, sphingosine, ceramide, and sphingosine-1-phosphate, in bone homeostasis. Sphingolipids are a major class of highly bioactive lipids able to activate distinct protein targets including, lipases, phosphatases, and kinases, thereby conferring distinct cellular functions beyond energy metabolism. Lipids are known to contribute to the progression of chronic inflammation, and notably, an increase in bone marrow adiposity parallel to elevated bone loss is observed in most pathological bone conditions, including aging, rheumatoid arthritis, osteoarthritis, and osteomyelitis. Of the numerous classes of lipids that form, sphingolipids are considered among the most deleterious. This review highlights the important primary role of sphingolipids in bone homeostasis and how dysregulation of these bioactive metabolites appears central to many chronic bone-related diseases. Further, their contribution to the invasion, virulence, and colonization of both viral and bacterial host cell infections is also discussed. Many unmet clinical needs remain, and data to date suggest the future use of sphingolipid-targeted therapy to regulate bone dysfunction due to a variety of diseases or infection are highly promising. However, deciphering the biochemical and molecular mechanisms of this diverse and extremely complex sphingolipidome, both in terms of bone health and disease, is considered the next frontier in the field.

The international cooperative Gaucher group (ICCG) Gaucher registry

Gaucher disease GD), is a rare lysosomal storage disorder caused by deficient acid β-glucosylceramidase activity and accumulation of glucosylceramide in tissue macrophages. With the 1991 advent of alglucerase enzyme replenishment therapy (ERT), the manufacturer (Genzyme Corporation) created the ICGG Gaucher Registry to collect longitudinal observational "real word" information about GD world-wide in heterogeneous patient populations, to annotate phenotypes and genotypes that define the natural history of GD in untreated patients, and to document and analyze treatment outcomes for alglucerase and any other future treatments. For 32 years, the ICGG Gaucher Registry has functioned as an educational tool for patients, clinicians, and other stakeholders to increase scientific knowledge of GD, to provide practical management guidance, and to positively impact patient care. This paper illustrates how an industry sponsored registry guided by a company independent scientific advisory board has successfully addressed its mission and evolved in step with technologic and scientific advances.

Pediatric Gaucher Disease Presenting with Massive Splenomegaly and Hepatic Gaucheroma

Gaucher Disease (GD) is a condition resulting from an autosomal recessive inheritance pattern, characterized by a deficiency of the lysosomal enzyme beta-glucocerebrosidase. This leads to the accumulation of glucocerebroside and other glycolipids in multiple tissues, causing damage to various organ systems. The diagnosis of GD can be challenging due to its heterogeneity, non-specific symptoms, and variability across different geographic regions and age groups. Although GD is suspected based on symptoms or signs, the diagnosis is confirmed through the measurement of deficient b-glucocerebrosidase activity and the identification of biallelic pathogenic variants in the GBA gene. Intravenous enzyme replacement therapy (ERT) is recommended for GD patients. In this paper, we report a case of a 2-year and 8-month-old girl with massive splenomegaly and radiological finding of hepatic gaucheroma, in whom a genetic study showed homozygous mutation on the GBA gene at c.1448T>C (p.Leu483Pro) and certified the diagnosis of GD. This patient represents the youngest child reported to have gaucheroma and also the first one presenting with gaucheroma at the diagnosis and not during the follow up, highlighting that GD should be routinely included in the differential diagnosis of children presenting with splenomegaly and hepatomegaly, taking into account that the early start of ERT can change the natural history of the disease-preventing serious complications.

Rare lysosomal disease registries: lessons learned over three decades of real-world evidence

Lysosomal storage disorders (LSD) are rare diseases, caused by inherited deficiencies of lysosomal enzymes/transporters, that affect 1 in 7000 to 1 in 8000 newborns. Individuals with LSDs face long diagnostic journeys during which debilitating and life-threatening events can occur. Clinical trials and classical descriptions of LSDs typically focus on common manifestations, which are not representative of the vast phenotypic heterogeneity encountered in real-world experience. Additionally, recognizing that there was a limited understanding of the natural history, disease progression, and real-world clinical outcomes of rare LSDs, a collaborative partnership was pioneered 30 years ago to address these gaps. The Rare Disease Registries (RDR) (for Gaucher, Fabry, Mucopolysaccharidosis type I, and Pompe), represent the largest observational database for these LSDs. Over the past thirty years, data from the RDRs have helped to inform scientific understanding and the development of comprehensive monitoring and treatment guidelines by creating a framework for data collection and establishing a standard of care, with an overarching goal to improve the quality of life of affected patients. Here, we highlight the history, process, and impact of the RDRs, and discuss the lessons learned and future directions.

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.

Skeletal involvement in Gaucher disease: extent of bone disease, splenic volume, and quality of life

Objective

To investigate the correlations among the extent of bone involvement, splenic volume, and quality of life in patients with Gaucher disease.

Materials and Methods

This was a descriptive, prospective cross-sectional study of 18 patients with Gaucher disease who underwent 3-T magnetic resonance imaging of both femurs and the lumbar spine. Semiquantitative analyses were performed on the basis of the bone marrow burden (BMB) score. We looked for linear relationships among the variables splenic volume, quality of life score, and BMB score.

Results

We identified a linear relationship between the BMB scores and splenic volume. The quality of life score showed no statistically significant relationship with splenic volume or the BMB score.

Conclusion

The linear relationship between the BMB score and the splenic volume indicates that the extent of bone disease is greater in individuals with splenomegaly. No correlation was found between the BMB and quality of life scores, illustrating the insidious and silent progression of Gaucher disease.

The International Collaborative Gaucher Group GRAF (Gaucher Risk Assessment for Fracture) score: a composite risk score for assessing adult fracture risk in imiglucerase-treated Gaucher disease type 1 patients

Background

Fractures in Gaucher disease type 1 (GD1) patients cause significant morbidity. Fracture risk may be decreased by enzyme replacement therapy (ERT) but not eliminated. When considering initiation of treatment, it is useful to know to what extent fixed patient-specific factors determine risk for future fractures beyond standard risk factors that change with time and treatment, such as decreased bone mineral density. We developed a tool called the GRAF score (Gaucher Risk Assessment for Fracture) that applies 5 widely available characteristics (sex, age at treatment initiation [ATI], time interval between diagnosis and treatment initiation, splenectomy status, history of pre-treatment bone crisis) and provides a practical method to assess future fracture risk when imiglucerase ERT is initiated.

Methods

Inclusion criteria: GD1 patients in the International Collaborative Gaucher Group Gaucher Registry as of September 2019 initially treated with alglucerase/imiglucerase; known splenectomy status; at least one skeletal assessment on treatment (3216 of 6422 patients). Data were analyzed by ATI group (< 18, ≥ 18 to < 50, or ≥ 50 years of age) using Cox proportional hazards regression with all 5 risk factors included in the multivariable model. A composite risk score was calculated by summing the contribution of each parameter weighted by the strength of its association (regression coefficient) with fracture risk.

Results

Patients were followed from the date of treatment initiation (or age 18 years for patients if treatment started earlier) to the date of first adult fracture (n = 288 first fracture endpoints), death, or end of follow-up. The GRAF score for each ATI group was associated with a 2.7-fold increased risk of adult fracture for each one-point increase (p < 0.02 for < 18 ATI, p < 0.0001 for ≥ 18 to < 50 ATI and ≥ 50 ATI).

Conclusions

The GRAF score is a tool to be used with bone density and other modifiable, non-GD-specific risk factors (e.g. smoking, alcohol intake, frailty) to inform physicians and previously untreated GD1 patients about risk for a future fracture after starting imiglucerase regardless of whether there is an eventual switch to an alternative ERT or to substrate reduction therapy. GRAF can also help predict the extent that fracture risk increases if initiation of treatment is further delayed.

A Quantitative Systems Pharmacology Model of Gaucher Disease Type 1 Provides Mechanistic Insight Into the Response to Substrate Reduction Therapy With Eliglustat

Gaucher’s disease type 1 (GD1) leads to significant morbidity and mortality through clinical manifestations, such as splenomegaly, hematological complications, and bone disease. Two types of therapies are currently approved for GD1: enzyme replacement therapy (ERT), and substrate reduction therapy (SRT). In this study, we have developed a quantitative systems pharmacology (QSP) model, which recapitulates the effects of eliglustat, the only first‐line SRT approved for GD1, on treatment‐naïve or patients with ERT‐stabilized adult GD1. This multiscale model represents the mechanism of action of eliglustat that leads toward reduction of spleen volume. Model capabilities were illustrated through the application of the model to predict ERT and eliglustat responses in virtual populations of adult patients with GD1, representing patients across a spectrum of disease severity as defined by genotype‐phenotype relationships. In summary, the QSP model provides a mechanistic computational platform for predicting treatment response via different modalities within the heterogeneous GD1 patient population.

Evaluation of the efficacy and safety of the biosimilar drug Glurazyme (imiglucerase) in patients with Gaucher disease type 1

Background. Gaucher disease (GD) is a rare hereditary condition, which represents the most common form of lysosomal storage diseases. Enzyme replacement therapy (ERT) with recombinant glucocerebrosidase is used for the treatment of type 1 and type 3 GD. Imiglucerase (recombinant glucocerebrosidase) is the first biotechnological ERT medication possessing confirmed clinical efficacy and safety.

Aim. To compare the efficacy and safety of the biosimilar drug Glurazyme and the reference drug Cerezyme during ERT therapy in patients with type 1 GD.

Materials and methods. Thirty patients aged from 19 to 63 years (33 ± 9.7 years) with a stable course of type 1 GD were enrolled in the study. The patients were randomly divided into two equal treatment groups, one of which received Glurazyme and the other received the reference drug Cerezyme. In both groups, the drugs were used in doses of 15–40 U/kg intravenously once every 14 days for 52 weeks.

Results. At the end of the study, at week 52 (primary endpoint of efficacy), both groups demonstrated a similar increase in hemoglobin concentration compared to the baseline data. In both groups, the average increase in hemoglobin concentration was 4.8 g/l, with this parameter varying between the groups by 0.1 g/l. At week 52, the calculated 95% confidence interval for the difference in hemoglobin concentration did not cross the non-inferiority margin of 18 g/l, which had been specified as the lower level of drug efficacy. This led to the conclusion that the studied drug Glurazyme is not inferior to Cerezyme in terms of efficacy. A comparison of the treatment groups by secondary endpoints of efficacy revealed: no decrease in hemoglobin concentration by more than 20 % in both groups; no differences between the groups by the number of patients with a change in platelet concentration relative to the baseline values; no increase in the spleen and liver volume by more than 20 and 10 %, respectively, in both groups. The doses of the drug under study and the reference drug remained unchanged during the research. The concentration of chemokine CCL-18 decreased slightly in 10 patients (64.3 %) and 6 patients (40 %) in the Glurazyme group and the Cerezyme group, respectively. The proportion of patients with improved physical and mental health components was 57.1 and 57.1 %, respectively, in the Glurazyme group compared to 73.3 and 60 %, respectively, in the Cerezyme group. Changes in the state of the bone tissue and the reserves of accumulated metabolites in the bone marrow showed a similar decrease in the severity of bone marrow infiltration in both groups.

Conclusions. Glurazyme and Cerezyme showed comparable parameters of efficacy and safety in patients with GD type 1 during long-term enzyme replacement therapy.

Jaw bones' involvement and dental features of type I and type III Gaucher disease: a radiographic study of 42 paediatric patients

PURPOSE

Gaucher disease (GD) is a lysosomal storage disease caused by an autosomal recessive inherited deficiency of the lysosomal enzyme glucocerebrosidase. The aim of this study is to describe jaw bones' involvement and dental radiographic features in paediatric Gaucher disease patients (type I and type III).

METHODS

The study population of this case-control study included: 42 Gaucher patients (study group) and 84 medically free children (control group). The radiographic images of both groups were analysed for the following findings: generalised bone rarefaction, localised rarefaction and enlarged bone marrow spaces, thinning of cortex, pseudocystic radiolucent lesions, anodontia and dental anomalies. Dental age assessment of Gaucher patients using the Demirjian's method was also performed.

RESULTS

Generalised rarefaction showed almost similar percentages in both types of Gaucher disease cases. Localised rarefaction was noted in 30.77% and 18.75% of Gaucher disease type III and type I, respectively. Pseudocystic radiolucent lesions, thinning of cortex, anodontia and dental anomalies were more prevalent in type III Gaucher patients. The mean chronological and mean dental ages in both sexes of Gaucher patients were not statistically significant.

CONCLUSION

Thinning of cortex, localised rarefaction and generalised rarefaction are the most common jaw bone findings in Gaucher patients.

Gaucher Disease in Bone: From Pathophysiology to Practice

Gaucher disease (GD) is a rare, genetic lysosomal disorder leading to lipid accumulation and dysfunction in multiple organs. Involvement of the skeleton is one of the most prevalent aspects of GD and a major cause of pain, disability, and reduced quality of life. Uniform recommendations for contemporary evaluation and management are needed. To develop practical clinical recommendations, an international group of experienced physicians conducted a comprehensive review of 20 years' of the literature, defining terms according to pathophysiological understanding and pointing out best practice and unmet needs related to the skeletal features of this disorder. Abnormalities of bone modeling, reduced bone density, bone infarction, and plasma cell dyscrasias accompany the displacement of healthy adipocytes in adult marrow. Exposure to excess bioactive glycosphingolipids appears to affect hematopoiesis and the balance of osteoblast and osteoclast numbers and activity. Imbalance between bone formation and breakdown induces disordered trabecular and cortical bone modeling, cortical bone thinning, fragility fractures, and osteolytic lesions. Regular assessment of bone mineral density, marrow infiltration, the axial skeleton and searching for potential malignancy are recommended. MRI is valuable for monitoring skeletal involvement: It provides semiquantitative assessment of marrow infiltration and the degree of bone infarction. When MRI is not available, monitoring of painful acute bone crises and osteonecrosis by plain X-ray has limited value. In adult patients, we recommend DXA of the lumbar spine and left and right hips, with careful protocols designed to exclude focal disease; serial follow-up should be done using the same standardized instrument. Skeletal health may be improved by common measures, including adequate calcium and vitamin D and management of pain and orthopedic complications. Prompt initiation of specific therapy for GD is crucial to optimizing outcomes and preventing irreversible skeletal complications. Investing in safe, clinically useful, and better predictive methods for determining bone integrity and fracture risk remains a need. © 2019 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

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.

Gene variants of osteoprotegerin, estrogen-, calcitonin- and vitamin D-receptor genes and serum markers of bone metabolism in patients with Gaucher disease type 1

Purpose

Osteopathy/osteoporosis in Gaucher disease type 1 (GD1) shows variable responses to enzyme replacement therapy (ERT); the pathogenesis is incompletely understood. We aimed to investigate the effects of several gene variants on bone mineral density (BMD) and serum markers of bone metabolism in GD1.

Patients and methods

Fifty adult Caucasian patients with GD1/117 controls were genotyped for gene variants in the osteoprotegerin (TNFRSF11B; OPG), estrogen receptor alpha, calcitonin receptor (CALCR), and vitamin D receptor (VDR) genes. In patients and 50 matched healthy controls, we assessed clinical data, serum markers of bone metabolism, and subclinical inflammation. BMD was measured for the first time before/during ERT (median 6.7 years).

Results

Forty-two percent of patients were splenectomized. ERT led to variable improvements in BMD. Distribution of gene variants was comparable between patients/controls. The AA genotype (c.1024+283G>A gene variant; VDR gene) was associated with lower Z scores before ERT vs GA (P=0.033), was encountered in 82.3% of patients with osteoporosis and was more frequent in patients with pathological fractures. Z score increases during ERT were higher in patients with the CC genotype (c.9C>G variant, TNFRSF11B; OPG gene; P=0.003) compared with GC (P=0.003). The CC genotype (c.1340T>C variant, CALCR gene) was associated with higher Z scores before ERT than the TT genotype (P=0.041) and was absent in osteoporosis. Osteocalcin and OPG were lower in patients vs controls; beta crosslaps, interleukin-6, and ferritin were higher.

Conclusions

We suggest for the first time a protective role against osteoporosis in GD1 patients for the CC genotype of the c.9C>G gene variant in the TNFRSFB11 (OPG) gene and for the CC genotype of the c.1340T>C gene variant (CALCR gene), while the AA genotype of the c.1024+283G>A gene variant in the VDR gene appears as a risk factor for lower BMDs. Serum markers suggest decreased osteosynthesis, reduced inhibition of osteoclast activation, increased bone resorption, and subclinical inflammation during ERT.

Impact of sphingolipids on osteoblast and osteoclast activity in Gaucher disease

Gaucher disease (GD) is an inherited disorder in which mutations in the GBA1 gene lead to deficient β-glucocerebrosidase activity and accumulation of its substrate glucosylceramide. Bone disease is present in around 84% of GD patients, ranging from bone loss including osteopenia and osteonecrosis to abnormal bone remodelling in the form of Erlenmeyer flask formation. The range of severity and variety of types of bone disease found in GD patients indicate the involvement of several mechanisms. Here we investigate the effects of exogenous sphingolipids on osteoclasts, osteoblasts, plasma cells and mesenchymal stem cells (MSC) and the interactions between these cell types. Osteoclasts were differentiated from the peripheral blood of Gaucher patients and control subjects. Osteoblasts were differentiated from mesenchymal stem cells isolated from bone marrow aspirates of Gaucher patients and control subjects. The human osteoblast cell line SaOS-2 was also investigated. Osteoclasts, osteoblasts and a human myeloma plasma cell line NCI-H929 were cultured with relevant exogenous sphingolipids to assess effects on cellular viability and function. Calcium deposition by osteoblasts differentiated from Gaucher patient MSC's was on average only 11.4% of that deposited by control subject osteoblasts. Culture with glucosylsphingosine reduced control subject MSC viability by 10.4%, SaOS-2 viability by 17.4% and plasma cell number by 40%. Culture with glucosylceramide decreased calcium deposition by control MSC-derived osteoblasts while increasing control subject osteoclast generation by 55.6%, Gaucher patient osteoclast generation by 37.6% and plasma cell numbers by up to 29.7%. Excessive osteoclast number and activity and reduced osteoblast activity may have the overall effect of an uncoupling between osteoclasts and osteoblasts in the GD bone microenvironment.

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.

Recent advances in the diagnosis and management of Gaucher disease

INTRODUCTION

Gaucher disease, the autosomal recessive deficiency of the lysosomal enzyme glucocerebrosidase, is associated with wide phenotypic diversity including non-neuronopathic, acute neuronopathic, and chronic neuronopathic forms. Overlap between types can render definitive diagnoses difficult. However, differentiating between the different phenotypes is essential due to the vast differences in clinical outcomes and response to therapy. Genotypic information is helpful, but cannot always be used to make clinical predictions. Current treatments for Gaucher disease, including enzyme replacement therapy and substrate reduction therapy, can reverse many of the non-neurological manifestations, but these therapies must be administered continually and are extremely costly.

AREAS COVERED

We reviewed the literature concerning the varied clinical presentations of Gaucher disease throughout the lifetime, along with treatment options, management goals, and current and future research challenges. A PubMed literature search was performed for relevant publications between 1991 to January 2018.

EXPERT COMMENTARY

Interest and research in the field of Gaucher disease is rapidly expanding. However, significant barriers remain in our ability to predict phenotype, assess disease progression using objective biomarkers, and determine optimal treatment strategy on an individual basis. As the field grows, we anticipate identification of genetic modifiers, new biomarkers, and small-molecule chaperone therapies, which may improve patient quality of life.

Taliglucerase alfa: safety and efficacy across 6 clinical studies in adults and children with Gaucher disease

Taliglucerase alfa is an enzyme replacement therapy (ERT) approved for treatment of adult and paediatric patients with Type 1 Gaucher disease (GD) in several countries and the first plant cell-expressed recombinant therapeutic protein approved by the US Food and Drug Administration for humans. Here, we review the findings across six key taliglucerase alfa clinical studies. A total of 33 treatment-naïve adult patients were randomized to taliglucerase alfa 30 U/kg or 60 U/kg in a 9-month, multicentre, randomized, double-blind, parallel-group, dose-comparison pivotal study, after which eligible patients continued into two consecutive extension studies; 17 treatment-naïve adult patients completed 5 total years of treatment with taliglucerase alfa. In the only ERT study focused on exclusively paediatric patients with GD, 11 treatment-naïve children were randomized to taliglucerase alfa 30 U/kg or 60 U/kg in a 12-month, multicentre, double-blind study; nine completed 3 total years of treatment in a dedicated paediatric extension study. The effect of switching patients from imiglucerase to taliglucerase alfa was also investigated in a separate 9-month study that included 26 adults and five children; 10 adults completed a total of 3 years and two children completed a total of 2.75 years of taliglucerase alfa treatment in the extension studies. All studies evaluated safety and spleen volume, liver volume, platelet count, haemoglobin concentration, and biomarkers as measures of efficacy. Detailed results from baseline through the end of these studies are presented. Taliglucerase alfa was well tolerated, and adverse events were generally mild/moderate in severity and transient. Treatment with taliglucerase alfa resulted in improvements (treatment-naïve patients) or stability (patients switched from imiglucerase) in visceral, haematologic, and biomarker parameters. Together, this comprehensive data set supports the treatment of adult and paediatric patients with GD who are naïve to ERT or who have previously been treated with imiglucerase.

Demographics and patient characteristics of 1209 patients with Gaucher disease: Descriptive analysis from the Gaucher Outcome Survey (GOS)

The Gaucher Outcome Survey (GOS) is an international Gaucher disease (GD) registry established in 2010 for patients with a confirmed GD diagnosis, regardless of GD type or treatment status, designed to evaluate the safety and long‐term effectiveness of velaglucerase alfa and other GD‐related treatments. As of February 25, 2017, 1209 patients had enrolled, the majority from Israel (44.3%) and the US (31.4%). Median age at GOS entry was 40.4 years, 44.1% were male, and 13.3% had undergone a total splenectomy. Most patients had type 1 GD (91.5%) and were of Ashkenazi Jewish ethnicity (55.8%). N370S/N370S was the most prevalent genotype, accounting for 44.2% of genotype‐confirmed individuals (n = 847); however, there was considerable variation between countries. A total of 887 (73.4%) patients had received ≥1 GD‐specific treatment at any time, most commonly imiglucerase (n = 587), velaglucerase alfa (n = 507), and alglucerase (n = 102). Hematological and visceral findings at the time of GOS entry were close to normal for most patients, probably a result of previous treatment; however, spleen volume of patients in Israel was almost double that of patients elsewhere (7.2 multiples of normal [MN] vs. 2.7, 2.9 and 4.9 MN in the US, UK and rest of world), which may be explained by a greater disease severity in this cohort. This analysis aimed to provide an overview of GOS and present baseline demographic and disease characteristics of participating patients to help improve the understanding of the natural history of GD and inform the overall management of patients with the disease.

Tandem mass spectrometry assay of β-glucocerebrosidase activity in dried blood spots eliminates false positives detected in fluorescence assay

Deficiency of β-Glucocerebrosidase (GBA) activity causes Gaucher Disease (GD). GD can be diagnosed by measuring GBA activity (Beutler and Kuhl, 1990). In this study, we assayed dried blood spots from a cohort (n=528) enriched for GBA mutation carriers (n=78) and GD patients (n=18) using both the tandem mass spectrometry (MS/MS) and fluorescence assays and their respective synthetic substrates. The MS/MS assay differentiated normal controls, which included GBA mutation carriers, from GD patients with no overlap. The fluorescence assay did not always differentiate normal controls including GBA mutation carriers from GD patients and false positives were observed. The MS/MS assay improved specificity compared to the fluorescence assay.

In vitro osteoclastogenesis from Gaucher patients' cells correlates with bone mineral density but not with Chitotriosidase

Gaucher disease (GD) is caused by mutations on the gene encoding for the lysosomal enzyme glucocerebrosidase. Type I GD (GD1) patients present anemia, hepatosplenomegaly and bone alterations. In spite of treatment, bone alterations in GD patients persist, including poor bone mineral density (BMD). Mechanisms leading to bone damage are not completely understood, but previous reports suggest that osteoclasts are involved. Chitotriosidase (CHIT) is the most reliable biomarker used in the follow up of patients, although its correlation with bone status is unknown. The aim of this work was to study the pro-osteoclastogenic potential in patients and to evaluate its correlation with CHIT activity levels and clinical parameters. PBMCs from treated patients and healthy controls were cultured in the presence of M-CSF, and mature osteoclasts were counted. BMD, blood CHIT activity and serum levels of CTX, BAP, and cytokines were evaluated in patients. We found that blood CHIT activity and osteoclast differentiation were significantly increased in patients, but no correlation between them was observed. Interestingly, osteoclast numbers but not CHIT, presented a negative correlation with BMD expressed as Z-score. CTX, BAP and serum cytokines involved in bone remodeling were found altered in GD1 patients. These results show for the first time a correlation between osteoclast differentiation and BMD in GD1 patients, supporting the involvement of osteoclasts in the bone pathology of GD1. Our results also suggest that an altered immune response may play an important role in bone damage.

Transformation in pretreatment manifestations of Gaucher disease type 1 during two decades of alglucerase/imiglucerase enzyme replacement therapy in the International Collaborative Gaucher Group (ICGG) Gaucher Registry

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

Assessment of Bone Health in Patients With Type 1 Gaucher Disease Using Impact Microindentation

Gaucher disease (GD), one of the most common lysosomal disorders (a global population incidence of 1:50,000), is characterized by beta-glucocerebrosidase deficiency. Some studies have demonstrated bone infiltration in up to 80% of patients, even if asymptomatic. Bone disorder remains the main cause of morbidity in these patients, along with osteoporosis, avascular necrosis, and bone infarcts. Enzyme replacement therapy (ERT) has been shown to improve these symptoms. This cross-sectional study included patients with type 1 Gaucher disease (GD1) selected from the Catalan Study Group on GD. Clinical data were collected and a general laboratory workup was performed. Bone mineral density (BMD) was measured at the lumbar spine and hip using dual-energy X-ray absorptiometry (DXA). Patients with bone infarcts or any other focal lesion in the area of indentation visible on imaging were excluded. Bone Material Strength index (BMSi) was measured by bone impact microindentation using an Osteoprobe instrument. Analysis of covariance (ANCOVA) models were fitted to adjust for age, sex, weight, and height. Sixteen patients with GD1 and 29 age- and sex-matched controls were included. GD1 was associated with significantly lower BMSi (adjusted beta -9.30; 95% CI, -15.18 to -3.42; p = 0.004) and reduced lumbar BMD (adjusted beta -0.14; 95% CI, -0.22 to -0.06; p = 0.002) and total hip BMD (adjusted beta -0.09; 95% CI, -0.15 to -0.03; p = 0.006), compared to GD1-free controls. Chitotriosidase levels were negatively correlated with BMSi (linear R²  = 51.6%, p = 0.004). Bone tissue mechanical characteristics were deteriorated in patients with GD1. BMSi was correlated with chitotriosidase, the marker of GD activity. Bone disorder requires special consideration in this group of patients, and microindentation could be an appropriate tool for assessing and managing their bone health. © 2017 American Society for Bone and Mineral Research.

Skeletal involvement in type 1 Gaucher disease: Not just bone mineral density

Gaucher disease is characterized by multi-organ infiltration of phospholipid-laden macrophages. Bone involvement is characterized by typical deformities, osteopenia/osteoporosis, pathological fractures, and bone marrow infiltration (avascular osteonecrosis, infarction). Estimation of skeletal disease includes bone quality that contributes substantially to bone strength. We studied 23 type 1 Gaucher patients (median age 22years, range 3-73) on Enzyme Replacement Therapy from 2months to 26years (median 7years); 4 patients had pathological fractures, 10 bone infarctions, 6 avascular osteonecrosis. We noninvasively assessed bone quality by trabecular microarchitecture and macroscopic geometry, using two innovative dual-energy X-ray absorptiometry tools: Trabecular Bone Score (TBS) and Hip Structural Analysis (HSA). Bone quality parameters distinguished the patients with skeletal complications. TBS was significantly lower in patients with avascular osteonecrosis (p=0.049) and pathological fractures (p=0.024), while it could not identify those with bone infarctions. Among HSA parameters, the Cross Sectional Area of the intertrochanteric region and the Buckling Ratio of the narrow neck allowed the distinction of patients with avascular osteonecrosis. BMD was low in 11 patients (50%); neither BMD nor HSA were associated with pathological fractures. The combined evaluation of bone quality and bone quantity is useful to identify GD patients with more severe skeletal involvement.

Diagnosis features of pediatric Gaucher disease patients in the era of enzymatic therapy, a national-base study from the Spanish Registry of Gaucher Disease

BACKGROUND

The enzymatic replacement therapy (ERT) availability for Gaucher disease (GD) has changed the landscape of the disease, several countries have screening programs. These actions have promoted the early diagnosis and avoided many complications in pediatric patients. In Spain ERT has been available since 1993 and 386 patients have been included in the Spanish Registry of Gaucher Disease (SpRGD). The aim of this study is to analyze the impact of ERT on the characteristics at time of diagnosis and initial complications in pediatric Gaucher disease patients.

AIM

To analyze the impact of ERT on the characteristics at time of diagnosis and initial complications in pediatric Gaucher disease patients.

METHODS

A review of data in SpRGD from patients' diagnosed before 18 years old was performed. The cohort was split according the year of diagnosis (≤1994, cohort A; ≥1995, cohort B).

RESULTS

A total of 98 pediatric patients were included, GD1: 80, GD3: 18; mean age: 7.2 (0.17-16.5) years, 58 (59.2%) males and 40 (40.8%) females. Forty-five were diagnosed ≤ 1994 and 53 ≥ 1995. Genotype: N370S/N370S: 2 (2.0%), N370S/L444P: 27 (27.5%), N370S/other: 47 (48%), L444P/L444P: 7 (7.1%), L444P/D409H: 2 (2.0%), L444P/other: 3 (6.2%), other/other: 10 (10.2%). The mean age at diagnosis was earlier in patients diagnosed after 1995 (p < 0.001) and different between the subtypes, GD1: 8.2 (0.2-16.5) years and GD3: 2.8 (0.17-10.2) years (p < 0.001). There were more severe patients in the group diagnosed before 1994 (p = 0.045) carrying L444P (2), D409H (2), G377S (1), G195W (1) or the recombinant mutation. The patients' diagnosed ≤1994 showed worse cytopenias, higher chance of bone vascular complications at diagnosis and previous spleen removal. The patients started ERT at a median time after diagnosis of 5.2 years [cohort A] and 1.6 years [cohort B] (p < 0.001).

CONCLUSIONS

The early diagnosis of Gaucher disease in the era of ERT availability has permitted to reduce the incidence of severe and irreversible initial complication in pediatric patients, and this has permitted better development of these patients. This is the largest pediatric cohort from a national registry.

A Review of Gaucher Disease Pathophysiology, Clinical Presentation and Treatments

Gaucher disease (GD, ORPHA355) is a rare, autosomal recessive genetic disorder. It is caused by a deficiency of the lysosomal enzyme, glucocerebrosidase, which leads to an accumulation of its substrate, glucosylceramide, in macrophages. In the general population, its incidence is approximately 1/40,000 to 1/60,000 births, rising to 1/800 in Ashkenazi Jews. The main cause of the cytopenia, splenomegaly, hepatomegaly, and bone lesions associated with the disease is considered to be the infiltration of the bone marrow, spleen, and liver by Gaucher cells. Type-1 Gaucher disease, which affects the majority of patients (90% in Europe and USA, but less in other regions), is characterized by effects on the viscera, whereas types 2 and 3 are also associated with neurological impairment, either severe in type 2 or variable in type 3. A diagnosis of GD can be confirmed by demonstrating the deficiency of acid glucocerebrosidase activity in leukocytes. Mutations in the GBA1 gene should be identified as they may be of prognostic value in some cases. Patients with type-1 GD-but also carriers of GBA1 mutation-have been found to be predisposed to developing Parkinson's disease, and the risk of neoplasia associated with the disease is still subject to discussion. Disease-specific treatment consists of intravenous enzyme replacement therapy (ERT) using one of the currently available molecules (imiglucerase, velaglucerase, or taliglucerase). Orally administered inhibitors of glucosylceramide biosynthesis can also be used (miglustat or eliglustat).

Ten plus one challenges in diseases of the lysosomal system

The advent of the first effective specific therapy for a lysosomal storage disease (LSDs), Gaucher disease type 1, by Roscoe O. Brady was foundational for development of additional treatments for this group of rare diseases. The past 26years, since the approval of enzyme therapy for Gaucher disease type 1, have witnessed a burgeoning understanding of LSDs at genetic, molecular, biochemical, cell biologic, and clinical levels. Simultaneously, this expansion of knowledge has exposed our incomplete understanding of the individual pathophysiologies of LSDs as well as difficult challenges for improvement in therapy and therapeutic outcomes for afflicted individuals. Here, 10 such challenges/problems representing major impediments, which need to be overcome, to move forward toward the goals of more effective and complete therapies for these devastating diseases.

Management and monitoring recommendations for the use of eliglustat in adults with type 1 Gaucher disease in Europe

PURPOSE

In Gaucher disease, diminished activity of the lysosomal enzyme, acid β-glucosidase, leads to accumulation of glucosylceramides and related substrates, primarily in the spleen, liver, and bone marrow. Eliglustat is an oral substrate reduction therapy approved in the European Union and the United States as a first-line treatment for adults with type 1 Gaucher disease who have compatible CYP2D6 metabolism phenotypes. A European Advisory Council of experts in Gaucher disease describes the characteristics of eliglustat that are distinct from enzyme augmentation therapy (the standard of care) and miglustat (the other approved substrate reduction therapy) and recommends investigations and monitoring for patients on eliglustat therapy within the context of current recommendations for Gaucher disease management.

RESULTS

Eliglustat is a selective, potent inhibitor of glucosylceramide synthase, the enzyme responsible for biosynthesis of glucosylceramides which accumulate in Gaucher disease. Extensive metabolism of eliglustat by CYP2D6, and, to a lesser extent, CYP3A of the cytochrome P450 pathway, necessitates careful consideration of the patient's CYP2D6 metaboliser status and use of concomitant medications which share metabolism by these pathways. Guidance on specific assessments and monitoring required for eliglustat therapy, including an algorithm to determine eligibility for eliglustat, are provided.

CONCLUSIONS

As a first-line therapy for type 1 Gaucher disease, eliglustat offers eligible patients a daily oral therapy alternative to biweekly infusions of enzyme therapy. Physicians will need to carefully assess individual Gaucher patients to determine their appropriateness for eliglustat therapy. The therapeutic response to eliglustat and use of concomitant medications will require long-term monitoring.

Imiglucerase in the management of Gaucher disease type 1: an evidence-based review of its place in therapy

Introduction

Gaucher disease is the first lysosomal disease to benefit from enzyme replacement therapy, thus serving as model for numerous other lysosomal diseases. Alglucerase was the first glucocerebrosidase purified from placental extracts, and this was then replaced by imiglucerase – a Chinese hamster ovary cell-derived glucocerebrosidase.

Aim

The aim was to review the evidence underlying the use of imiglucerase in Gaucher disease type 1

Evidence review

Data from clinical trials and Gaucher Registries were analyzed.

Conclusion

Imiglucerase has been prescribed and found to have an excellent efficacy and safety profile. We report herein the evidence-based data published for 26 years justifying the use of imiglucerase.

Early manifestations of type 1 Gaucher disease in presymptomatic children diagnosed after parental carrier screening

PURPOSE

The overall published experience with pediatric type 1 Gaucher disease (GD1) has been based on ascertainment through clinical presentation of the disease. We describe the longitudinal follow-up in a presymptomatic pediatric cohort.

METHODS

The cohort includes children diagnosed with GD1, either prenatally or postnatally by molecular genetic testing, and followed for clinical care at our center from 1998 to 2016. All patients' parents were GBA mutation carriers identified through carrier screening programs. Longitudinal clinical, laboratory, and imaging data were obtained through chart review.

RESULTS

Thirty-eight patients aged 1-18 years (mean at last visit 6.9 ± 4.1 years) were followed, including 32 p.N409S homozygotes and 6 p.N409S/p.R535H compound heterozygotes. At the last evaluation, a minority had hematological (5%), bone (15%), or linear growth (19%) issues. Only 12% had splenomegaly and 74% had moderate hepatomegaly. Chitotriosidase activity varied widely (6-5,640 nmol/hour/ml) and generally increased with age. Pediatric Gaucher severity scores (GSS) remained stable and within the mild-disease range for most (95%). Treatment for progressive disease during this period was recommended for four children.

CONCLUSION

Most children with the p.N409S/p.N409S and p.N409S/p.R535H GD1 genotypes have minimal disease manifestations and progression during childhood and can be monitored using limited assessments. Those with other mutations may require additional monitoring. These data are valuable for newborn screening and counseling.Genet Med advance online publication 13 October 2016.

Evaluation of Bone Mineral Density in Patients with Type 1 Gaucher Disease in Argentina

The purpose of this study was to evaluate the frequency of osteoporosis (OP) in patients with Gaucher disease (GD) in Argentina. GD patients from 28 centers were consecutively included from April 2012 to 2014. Bone mineral density (BMD) was determined by dual X-ray absorptiometry in the lumbar spine and the femoral neck or the total proximal femur for patients ≥20 yr of age, and by whole-body scan in the lumbar spine in patients <20 yr of age. In children, mineral density was calculated using the chronological age and Z height. OP diagnosis was determined following adult and pediatric official position of the International Society for Clinical Densitometry. A total of 116 patients were included, of which 62 (53.5%) were women. The median age was 25.8 yr. All patients received enzyme replacement therapy, with a median time of 9.4 yr. Normal BMD was found in 89 patients (76.7%), whereas low bone mass (LBM) or osteopenia was found in 15 patients (13%) and OP in 12 patients (10.3%). The analysis of the pediatric population revealed that 4 patients (9.3%) had LBM and 3 (7%) had OP (Z-score ≤ -2 + fractures height-adjusted by Z), whereas in the adult population (n = 73), 11 patients (15%) had LBM or osteopenia and 9 (12.3%) had OP. Bone marrow infiltration and the presence of fractures were significantly correlated with the presence of OP (p = 0.04 and <0.001, respectively). This is the first study in Argentina and in the region describing the frequency of OP or LBM in GD patients treated with imiglucerase using the official position of the International Society for Clinical Densitometry.

Comparison of Bone Mineral Density by Dual-Energy X-Ray Absorptiometry and Bone Strength by Speed-of-Sound Ultrasonography in Adults With Gaucher Disease

Patients with the lysosomal disorder Gaucher disease (GD) are at risk of osteoporosis and/or avascular necrosis, but to date, no adequate biomarkers are available to ascertain individual predilections. Bone mineral density by dual-energy X-ray absorptiometry (DXA) has traditionally been used to monitor trends. With the availability of a speed-of-sound (SOS) ultrasonography to assess bone strength/elasticity, we aimed to ascertain whether these modalities are complimentary or comparable so SOS, with no radiation risk, might be used more routinely as a potential biomarker. A prospective comparative study in adult GD patients undergoing routine follow-up of bone mineral density T- and Z-scores at forearm (FA), femoral neck, and lumbar spine, and SOS Z-scores at FA was initiated. Interpretation was by qualitative categorization of Z-scores. The kappa measure of agreement beyond chance was calculated between pairs of measurements and the McNemar test was then applied. This noninterventional trial (ClinicalTrials.gov Identifier: NCT02067247) was approved by the institutional ethics committee. There were 89 patients (ages 21-78 years, 61% female, 62% common Ashkenazi genotype, 18% splenectomized, and 18% with avascular necrosis/fractures). When comparing Z-scores at FA by DXA and SOS, only 39.3% correlated, while the remaining results were in disagreement; no trend was noted. Similarly, when comparing Z-scores at the femoral neck by DXA with those at FA by SOS, 44.9% of the results were in agreement; no trend was noted; and Z-scores at the lumbar spine by DXA with FA by SOS, 46% were in agreement and no trend was noted. DXA at the 3 sites did not track in the same direction or the same magnitude of difference with SOS at FA in adult patients with GD. Due to the fundamental differences between the 2 measurements and their clinical correlates, plus the lack of long-term follow-up to assess outcome, the potential added value of the measurements at the FA by SOS in patients with GD awaits further studies.

Skeletal involvement in Gaucher disease: An observational multicenter study of prognostic factors in the Argentine Gaucher disease patients

Patients with Gaucher type 1 (GD1) throughout Argentina were enrolled in the Argentine bone project to evaluate bone disease and its determinants. We focused on presence and predictors of bone lesions (BL) and their relationship to therapeutic goals (TG) with timing and dose of enzyme replacement therapy (ERT). A total of 124 patients on ERT were enrolled in a multi-center study. All six TG were achieved by 82% of patients: 70.1% for bone pain and 91.1% for bone crisis. However, despite the fact that bone TGs were achieved, residual bone disease was present in 108 patients on ERT (87%) at time 0. 16% of patients showed new irreversible BL (bone infarcts and avascular osteonecrosis) despite ERT, suggesting that they appeared during ERT or were not detected at the moment of diagnosis. We observed 5 prognostic factors that predicted a higher probability of being free of bone disease: optimal ERT compliance; early diagnosis; timely initiation of therapy; ERT initiation dose ≥45 UI/kg/EOW; and the absence of history of splenectomy. Skeletal involvement was classified into 4 major phenotypic groups according to BL: group 1 (12.9%) without BL; group 2 (28.2%) with reversible BL; group 3 (41.9%) with reversible BL and irreversible chronic BL; and group 4 (16.9%) with acute irreversible BL. Our study identifies prognostic factors for achieving best therapeutic outcomes, introduces new risk stratification for patients and suggests the need for a redefinition of bone TG. Am. J. Hematol. 91:E448-E453, 2016. © 2016 Wiley Periodicals, Inc.

Recommendations for the use of eliglustat in the treatment of adults with Gaucher disease type 1 in the United States

In Gaucher disease, deficient activity of acid β-glucosidase results in accumulation of its substrates, glucosylceramide and glucosylsphingosine, within the lysosomes of cells primarily in the spleen, liver, bone marrow, and occasionally the lung. The multisystem disease is predominantly characterized by hepatosplenomegaly, anemia, thrombocytopenia, and skeletal disease. Enzyme replacement therapy with recombinant human acid β-glucosidase has been the first-line therapy for Gaucher disease type 1 for more than two decades. Eliglustat, a novel oral substrate reduction therapy, was recently approved in the United States and the European Union as a first-line treatment for adults with Gaucher disease type 1. Eliglustat inhibits glucosylceramide synthase, thereby decreasing production of the substrate glucosylceramide and reducing its accumulation. Although existing recommendations for the care of patients with Gaucher disease remain in effect, unique characteristics of eliglustat require additional investigation and monitoring. A panel of physicians with expertise in Gaucher disease and experience with eliglustat in the clinical trials provide guidance regarding the use of eliglustat, including considerations before starting therapy and monitoring of patients on eliglustat therapy.

Gaucher Disease: Clinical, Biological and Therapeutic Aspects

We present a brief review of Gaucher disease (GD), the most common lysosomal storage disease. GD is a rare autosomal recessive disorder characterized by the defective function of the catabolic enzyme β-glucocerebrosidase (GBA), leading to an accumulation of its substrate, glucocerebroside. Clinical signs and symptoms include neurological dysfunctions, bone infarcts and malformations, hepatosplenomegaly and hypersplenism leading to anemia, neutropenia and thrombocytopenia. Enzyme replacement therapy with recombinant GBA is the mainstay of treatment for GD, which became the first successfully managed lipid storage disease. Future treatments may include oral enzyme replacement and/or gene therapy interventions.

Long-term treatment outcomes in Gaucher disease

Following the treatment of the first Gaucher disease patient with enzyme replacement therapy (ERT), it was clear that ERT had the potential to be transformative with dramatic improvements in systemic manifestations of the disease within 2 years. Following over 20 years existence of the International Collaborative Gaucher Group Gaucher Registry and evidence from ∼6000 patients, the long-term effects of therapy have been documented. It has been shown that ERT can result in improvements in all clinical and laboratory parameters of nonneuronopathic disease. However, different aspects of the disease, such as hematologic parameters, organ volumes and bone disease do not necessarily respond to therapy at the same rate or to the same extent, and this has had major implications for disease monitoring and for the establishment of therapeutic goals for ERT. Response may be affected by factors such as the timing of therapy initiation, the presence of irreversible complications such as osteonecrosis, and by enzyme dose. It is also apparent that ERT has no impact on neurological aspects of disease and highlights the need for additional or alternative treatment strategies able to meet the needs of patients with neuronopathic disease.

Gaucher disease types 1 and 3: Phenotypic characterization of large populations from the ICGG Gaucher Registry

Study of the natural history of Gaucher disease has revealed marked phenotypic variation. Correlations to genotypes could provide insight into individual susceptibility to varying disease severity, which may impact whole-life medical care, reproductive decisions, and therapeutic choices for affected families. Importantly, pre-symptomatic or prospective interventions or the use of therapies with significant risk require accurate risk-benefit analyses based on the prognosis for individual patients. The body of international data held within the International Collaborative Gaucher Group (ICGG) Gaucher Registry provides an unprecedented opportunity to characterize the phenotypes of Gaucher disease types 1 and 3 and to appreciate demographic and ethnic factors that may influence phenotypes. The diversity of GBA gene mutations from patients with Gaucher disease represented in the ICGG Gaucher Registry database and in the literature provides the basis for initial genotype/phenotype correlations, the outcomes of which are summarized here.