Gaucher's disease: clinical features and natural history

Macrophage-derived soluble CD163 level in young patients with Gaucher disease: relation to phenotypes, disease severity and complications

OBJECTIVES

Bone and lung involvement are two major causes of morbidity in Gaucher disease (GD). The soluble form of CD163 (sCD163) is a valuable diagnostic biomarker for monitoring diseases with increased macrophage activation. We determined sCD163 levels in 30 children and adolescence with GD compared with 30 healthy controls and assessed the relation to phenotypes, disease severity and complications.

METHODS

Thirty GD patients (10 had type 1 and 20 had type 3) were studied stressing on skeletal, pulmonary or neurological manifestations, enzyme replacement therapy (ERT), hematological profile, plasma chitotriosidase activity, D-dimer and sCD163. Liver and spleen volumes and bone mineral density (BMD) were assessed.

RESULTS

sCD163 levels were markedly elevated in patients compared with controls. D-dimer, chitotriosidase activity and sCD163 levels were significantly increased in type 3 GD patients compared with type 1. sCD163 was significantly elevated in GD patients with dysphagia, developmental delay, pulmonary hypertension risk or abnormal BMD (osteopenia/osteoporosis) than those without. GD patients receiving ERT every 2weeks had lower levels than those under ERT for more than 2weeks. sCD163 was positively correlated with age, disease duration, severity score index, D-dimer and chitotriosidase activity. The cutoff value of sCD163 at 9400ng/mL could differentiate GD patients with and without pulmonary hypertension risk with a sensitivity of 90% and specificity of 95%.

CONCLUSIONS

sCD163 is a biomarker for the clinical assessment of macrophage proliferation and activity that would help in risk prediction of bone and lung involvement and monitoring treatment response.

Red cell adhesion in human diseases

PURPOSE OF REVIEW

This review discusses the unexpected role of red blood cell (RBC) adhesiveness in the pathophysiology of two red cell diseases, hereditary spherocytosis and polycythemia vera, and two 'nonerythroid' disorders, central retinal vein occlusion and Gaucher disease. These pathologies share common clinical manifestations, that is vaso-occlusion and/or thrombotic events.

RECENT FINDINGS

Recently, the direct involvement of RBC adhesion to the vascular endothelium has been demonstrated in the occurrence of vaso-occlusive events, in particular in sickle cell disease (SCD). Several erythroid adhesion molecules and their ligands have been identified that belong to different molecular classes (integrins, Ig-like molecules, lipids...) and are activated by a variety of signaling pathways. Among these, the laminin receptor, Lutheran/basal cell adhesion molecule, which is activated by phosphorylation, appears to play a central role in several pathologies.

SUMMARY

RBC adhesiveness might be involved in complications such as the vaso-occlusive crisis in SCD, thrombosis in polycythemia vera, splenic sequestration in hereditary spherocytosis, occlusions in central retinal vein occlusion and bone infarcts in Gaucher disease. Characterization of this pathological process at the cellular and molecular levels should prove useful to develop new therapeutic approaches based on the blockade of RBC abnormal interactions with vascular endothelium and/or circulating blood cells.

Emerging therapeutic targets for Gaucher disease

INTRODUCTION

Gaucher disease (GD) is an inherited metabolic disorder caused by mutations in the glucocerebrosidase (GBA1) gene. Although infusions of recombinant GBA ameliorate the systemic effects of GD, this therapy has no effect on the neurological manifestations. Patients with the neuronopathic forms of GD (nGD) are often severely disabled and die prematurely. The search for innovative drugs is thus urgent for the neuronopathic forms.

AREAS COVERED

Here we briefly summarize the available treatments for GD. We then review recent studies of the molecular pathogenesis of GD, which suggest new avenues for therapeutic development.

EXPERT OPINION

Existing treatments for GD are designed to target the primary consequence of the inborn defects of sphingolipid metabolism, that is, lysosomal accumulation of glucosylceramide (GlcCer). Here we suggest that targeting other pathways, such as those that are activated as a consequence of GlcCer accumulation, may also have salutary clinical effects irrespective of whether excess substrate persists. These pathways include those implicated in neuroinflammation, and specifically, receptor-interacting protein kinase-3 (RIP3) and related components of this pathway, which appear to play a vital role in the pathogenesis of nGD. Once available, inhibitors to components of the RIP kinase pathway will hopefully offer new therapeutic opportunities in GD.

Sphingolipid lysosomal storage disorders

Lysosomal storage diseases are inborn errors of metabolism, the hallmark of which is the accumulation, or storage, of macromolecules in the late endocytic system. They are monogenic disorders that occur at a collective frequency of 1 in 5,000 live births and are caused by inherited defects in genes that mainly encode lysosomal proteins, most commonly lysosomal enzymes. A subgroup of these diseases involves the lysosomal storage of glycosphingolipids. Through our understanding of the genetics, biochemistry and, more recently, cellular aspects of sphingolipid storage disorders, we have gained insights into fundamental aspects of cell biology that would otherwise have remained opaque. In addition, study of these disorders has led to significant progress in the development of therapies, several of which are now in routine clinical use. Emerging mechanistic links with more common diseases suggest we need to rethink our current concept of disease boundaries.

Patients with type 1 Gaucher disease in South Florida, USA: demographics, genotypes, disease severity and treatment outcomes

Background

Gaucher disease, an autosomal recessive condition due to deficiency of lysosomal glucocerebrosidase, is a multisystemic disease, with variable age of onset, severity and progression. It is classified into subtypes delineated by the absence (type 1) or presence (type 2 and 3) of primary nervous system involvement.

The ethnically diverse, largely immigrant population in South Florida has a spectrum of Gaucher disease phenotypes, creating a challenge for optimization of disease management and an opportunity to explore treatment patterns.

Methods

Ninety-three records from patients with Gaucher type I in South Florida were retrieved from the International Collaborative Gaucher Group (ICGG) Registry. Individual genotypes were correlated with severity scores and success at achieving published therapeutic goals for haemoglobin concentration, platelet count, spleen volume, liver volume and amelioration of bone pain and bone crises.

Results

The majority of patients were diagnosed during the fifth decade of life. Almost two-thirds were homozygous for the N370S mutation, reflecting the large Ashkenazi Jewish population in South Florida. The majority received imiglucerase (62.8%) at various intervals. 24.5% of patients underwent splenectomy before starting enzyme replacement therapy. After a median 12 treatment years, South Florida patients matched or exceeded the ICCG 4 year therapeutic goal achievement for platelet count (85.4% vs. 79.6% success), spleen volume (93.3% vs. 78.0% success), liver volume (93.4% vs. 90.6% success), and bone crises (100% vs. 99% success). Nevertheless, fewer patients with intact spleens had sustained achievement of all 6 therapeutic goals (30.4% versus 41.4%) and only 40% of the splenectomy patients sustained achievement of 5/5 possible goals. 54.7% of the intact spleen patients continued to have bone pain vs. 29.8% in ICCG. Significantly, only 37% of the ICGG patient cohort had bone pain prior to initiation of treatment compared to 73.4% of the South Florida patients (moderate or severe pain in 59.6%).

Conclusions

Demographic characteristics are a significant determinant of the differences in response to treatment observed in South Florida Gaucher patients compared to those described in the international population enrolled in the ICGG Gaucher Registry. Individual genotypes and ethnic background are important considerations for optimizing patient care for Gaucher disease.

Chronic neuronopathic type of Gaucher’s disease with progressive myoclonic epilepsy in the absence of visceromegaly and bone involvement

Introduction

Gaucher’s disease is a lysosomal storage disorder caused by the deficiency of glucocerebrosidase. Gaucher’s disease has three clinical types: non-neuronopathic (Type 1), Acute Neuropathic (Type 2) and chronic neuronopathic (Type 3). The chronic neuronopathic (Type 3) is characterised by a variety of disease variants with onset in childhood with hepatomegaly, skeletal lesions and later slow horizontal saccades, treatment-resistant generalised tonic–clonic and myoclonic seizures, dementia, progressive spasticity, cognitive deterioration, ataxia and death in the second or third decade of life.

Case presentation

We describe a case of a 17-year-old girl who was born normally but subsequently developed treatment-refractory seizures at the age of nine with myoclonus, oculomotor apraxia, ataxia and cognitive decline. Enzyme activity of beta-glucocerebrosidase was found to be low without visceromegaly or bone involvement.

Conclusion

Screening for lysosomal enzyme activity should be done in patients exhibiting features suggestive of progressive myoclonic epilepsy.

Gaucher disease: haematological presentations and complications

Gaucher disease (GD) is an autosomal recessive lysosomal storage disease, caused by deficiency of the enzyme glucocerebrosidase, required for the degradation of glycosphingolipids. Clinical manifestations include hepatosplenomegaly, thrombocytopenia, bone disease and a bleeding diathesis, frequently resulting in presentation to haematologists. Historically managed by splenectomy, transfusions and orthopaedic surgery, the development of specific therapy in the form of intravenous enzyme replacement therapy in the 1990s has resulted in dramatic improvements in haematological and visceral disease. Recognition of complications, including multiple myeloma and Parkinson disease, has challenged the traditional macrophage-centric view of the pathophysiology of this disorder. The pathways by which enzyme deficiency results in the clinical manifestations of this disorder are poorly understood; altered inflammatory cytokine profiles, bioactive sphingolipid derivatives and alterations in the bone marrow microenvironment have been implicated. Further elucidating these pathways will serve to advance our understanding not only of GD, but of associated disorders.

Glucocerebrosidase mutations and the pathogenesis of Parkinson disease

Parkinson disease (PD) is the second most common neurodegenerative disease after Alzheimer disease with a lifetime risk in the UK population of almost 5%. An association between PD and Gaucher disease (GD) derived from the observation that GD patients and their heterozygous carrier relatives were at increased risk of PD. GD is an autosomal recessive lysosomal storage disorder caused by homozygous mutations in the gene encoding glucocerebrosidase (GBA). Approximately 5%-10% of PD patients have GBA mutations, making these mutations numerically the most important genetic predisposing risk factor for the development of PD identified to date. GBA mutations result in a phenotype that is virtually indistinguishable clinically, pharmacologically, and pathologically from sporadic PD, except GBA mutations result in a slightly earlier age of onset and more frequent cognitive impairment among PD patients. The mechanisms by which GBA mutations result in PD are not yet understood. Both reduced glucocerebrosidase enzyme (GCase) activity with lysosomal dysfunction, and unfolded protein response (UPR) with endoplasmic reticulum-associated degradation (ERAD) and stress are considered contributory.

Evoked potentials and neurocognitive functions in pediatric Egyptian Gaucher patients on enzyme replacement therapy: a single center experience

BACKGROUND

Effectiveness of enzyme replacement therapy (ERT) in reverting hematologic, skeletal, and visceral symptoms in Gaucher disease (GD) has been demonstrated, although, its efficacy in neurologic involvement is still debated.

AIM

We evaluated the extent of neuro-cognitive dysfunction using brain stem evoked potential in GD3 patients, age-matched controls, and GD1 patients without neurological manifestations served as disease control group.

METHODS

Study included 56 GD (36 had type 1, 20 had type 3) under ERT. Investigations included complete blood count, beta glucosidase assay in peripheral leucocytes, plasma chitotriosidase and bone marrow examination, electroencephalography, brain stem auditory (AEP), somatosensory (SSEP) and visual evoked potentials (VEP) as well as IQ testing.

RESULTS

Both types of GD showed significantly higher mean latency at 75 on left eye, lower PP amplitude ratio, higher latency at 75, 100, 145, lower amplitude, and higher Lat Diff LT-RT ms and Lt-Rt % compared to controls (p < 0.05) with no difference between both groups in other values of VEP. Both groups showed significantly prolonged latency of N 13-19 compared to controls (p < 0.05) with positive correlation between age and duration of therapy with parameters of SSEP (p < 0.01). Both groups of GD had significantly prolonged latency of the mean waves of AEP compared to controls (p < 0.05) with no significant difference between both groups. There was a negative correlation between age and waves II, III, I-III, I-V and threshold values of AEP. IQ level was positively correlated with AEP values. Severity scoring tool was positively correlated with AEP and SSEP values.

CONCLUSIONS

Electrophysiological abnormalities were present in both types of GD and have been correlated to cognitive function and disease characteristics.

Functional and genetic characterization of the non-lysosomal glucosylceramidase 2 as a modifier for Gaucher disease

Background

Gaucher disease (GD) is the most common inherited lysosomal storage disorder in humans, caused by mutations in the gene encoding the lysosomal enzyme glucocerebrosidase (GBA1). GD is clinically heterogeneous and although the type of GBA1 mutation plays a role in determining the type of GD, it does not explain the clinical variability seen among patients. Cumulative evidence from recent studies suggests that GBA2 could play a role in the pathogenesis of GD and potentially interacts with GBA1.

Methods

We used a framework of functional and genetic approaches in order to further characterize a potential role of GBA2 in GD. Glucosylceramide (GlcCer) levels in spleen, liver and brain of GBA2-deficient mice and mRNA and protein expression of GBA2 in GBA1-deficient murine fibroblasts were analyzed. Furthermore we crossed GBA2-deficient mice with conditional Gba1 knockout mice in order to quantify the interaction between GBA1 and GBA2. Finally, a genetic approach was used to test whether genetic variation in GBA2 is associated with GD and/ or acts as a modifier in Gaucher patients. We tested 22 SNPs in the GBA2 and GBA1 genes in 98 type 1 and 60 type 2/3 Gaucher patients for single- and multi-marker association with GD.

Results

We found a significant accumulation of GlcCer compared to wild-type controls in all three organs studied. In addition, a significant increase of Gba2-protein and Gba2-mRNA levels in GBA1-deficient murine fibroblasts was observed. GlcCer levels in the spleen from Gba1/Gba2 knockout mice were much higher than the sum of the single knockouts, indicating a cross-talk between the two glucosylceramidases and suggesting a partially compensation of the loss of one enzyme by the other. In the genetic approach, no significant association with severity of GD was found for SNPs at the GBA2 locus. However, in the multi-marker analyses a significant result was detected for p.L444P (GBA1) and rs4878628 (GBA2), using a model that does not take marginal effects into account.

Conclusions

All together our observations make GBA2 a likely candidate to be involved in GD etiology. Furthermore, they point to GBA2 as a plausible modifier for GBA1 in patients with GD.

Enhanced differentiation of osteoclasts from mononuclear precursors in patients with Gaucher disease

Gaucher disease (GD) is an autosomal recessive disorder caused by deficiency of β-glucocerebrosidase. Storage of glucosylceramide in reticuloendothelial cells results in multiorgan pathology including bone disease. Established skeletal disease may remain problematic despite Gaucher-specific treatment. Both osteopenia and osteonecrosis have been described but the underlying pathophysiology, in particular the role of monocyte-derived osteoclasts is not well defined. The objective of this study was to explore the effect of glucocerebrosidase deficiency, inhibition and replacement on osteoclast development and function. In cultures derived from GD patients, or where GBA was chemically inhibited multinucleate giant cells expressing markers of osteoclast differentiation occurred earlier and in greater numbers compared to normal controls and the functional capacity of osteoclasts for bone resorption was enhanced. Increases in osteoclast number and activity correlated with radiological markers of active bone disease. Abnormalities were reversed by addition of specific therapies and were attenuated by co-culture with cells derived from healthy controls (HCs). Numbers of osteoblast lineage cells in the peripheral blood were mismatched to osteoclast precursors indicating uncoupling of osteoblast-osteoclast regulation which may further impact on bone remodelling. Elucidation of the underlying mechanisms of these changes will suggest rational therapies for the most disabling aspect of this condition.

Revised recommendations for the management of Gaucher disease in children

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

CONCLUSION

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

Velaglucerase alfa enzyme replacement therapy compared with imiglucerase in patients with Gaucher disease

Enzyme replacement therapy for Gaucher disease (GD) has been available since 1991. This study compared the efficacy and safety of velaglucerase alfa with imiglucerase, the previous standard of care. A 9-month, global, randomized, double-blind, non-inferiority study compared velaglucerase alfa with imiglucerase (60 U/kg every other week) in treatment-naïve patients aged 3-73 years with anemia and either thrombocytopenia or organomegaly. The primary endpoint was the difference between groups in mean change from baseline to 9 months in hemoglobin concentration. 35 patients were randomized: 34 received study drug (intent-to-treat: 17 per arm), 20 were splenectomized. Baseline characteristics were similar in the two groups. The per-protocol population included 15 patients per arm. The mean treatment difference for hemoglobin concentration from baseline to 9 months (velaglucerase alfa minus imiglucerase) was 0.14 and 0.16 g/dL in the intent-to-treat and per-protocol populations, respectively. The lower bound of the 97.5% one-sided confidence interval in both populations lay within the pre-defined non-inferiority margin of -1.0 g/dL, confirming that velaglucerase alfa is non-inferior to imiglucerase. There were no statistically significant differences in the secondary endpoints. Most adverse events were mild to moderate. No patient receiving velaglucerase alfa developed antibodies to either drug, whereas four patients (23.5%) receiving imiglucerase developed IgG antibodies to imiglucerase, which were cross-reactive with velaglucerase alfa in one patient. This study demonstrates the efficacy and safety of velaglucerase alfa compared with imiglucerase in adult and pediatric patients with GD clinically characterized as Type 1. Differences in immunogenicity were also observed.

Enzyme replacement therapy with velaglucerase alfa in Gaucher disease: Results from a randomized, double-blind, multinational, Phase 3 study

Type 1 Gaucher disease (GD1), resulting from glucocerebrosidase deficiency, leads to splenomegaly, hepatomegaly, anemia, thrombocytopenia, and bone involvement. Current standard treatment is enzyme replacement therapy. Velaglucerase alfa is an enzyme replacement product for GD1, with the same amino acid sequence as naturally occurring human glucocerebrosidase. This multinational, Phase 3 trial evaluated the efficacy and safety of two doses of velaglucerase alfa in 25 treatment-naïve, anemic patients with GD1 (4-62 years of age), randomized to intravenous velaglucerase alfa 60 U/kg (n=12) or 45 U/kg body weight (n=13) every other week for 12 months. The primary endpoint was change from baseline in hemoglobin concentration in the 60 U/kg arm. At 12 months, mean hemoglobin concentrations increased from baseline [60 U/kg: +23.3%; +2.43 g/dL (P<0.001); 45 U/kg: +23.8%; +2.44 g/dL (P<0.001)], as did mean platelet counts [60 U/kg: +65.9%; +50.9 × 10(9) /L (P=0.002); 45 U/kg: +66.4%; +40.9 × 10(9) /L(P=0.01)]. Mean splenic volume decreased from baseline [60 U/kg: -50.4%, from 14.0 to 5.8 multiples of normal (MN) (P=0.003); 45 U/kg: -39.9%, from 14.5 to 9.5 MN (P=0.009)]. No drug-related serious adverse events or withdrawals were observed. One patient developed antibodies. Velaglucerase alfa was generally well tolerated and effective for adults and children with GD1 in this study. All disease-specific parameters measured demonstrated clinically meaningful improvements after 12 months.

Neuronal forms of Gaucher disease

Gaucher disease is an inherited metabolic disease caused by the defective activity of the lysosomal enzyme, glucosylceramidase (GlcCerase), which is responsible for the last step in the degradation of complex glycosphingolipids. As a result, glucosylceramide (GlcCer) accumulates intracellularly. Little is known about the mechanisms by which GlcCer accumulation leads to Gaucher disease, particularly for the types of the disease in which severe neuropathology occurs. We now summarize recent advances in this area and in particular focus in the biochemical and cellular pathways that may cause neuronal defects. Most recent work has taken advantage of newly available mouse models, which mimic to a large extent human disease progression. Finally, we discuss observations of a genetic link between Gaucher disease and Parkinson's disease and discuss how this link has stimulated research into the basic biology of the previously underappreciated glycosphingolipid, GlcCer.

Evaluation of miglustat as maintenance therapy after enzyme therapy in adults with stable type 1 Gaucher disease: a prospective, open-label non-inferiority study

Background

Previous studies have provided equivocal data on the use of miglustat as maintenance therapy in Gaucher disease type 1. We report findings from a clinical trial evaluating the effects of miglustat treatment in patients with stable type 1 Gaucher disease after enzyme therapy.

Methods

Adult type 1 Gaucher disease patients stabilized during at least 3 years of previous enzyme therapy were included in this 2-year, prospective, open-label non-inferiority study. The primary endpoint was percent change from baseline in liver volume. Secondary endpoints included changes in spleen volume, hemoglobin concentration and platelet count.

Results

Forty-two patients were enrolled (mean±SD age, 45.1±12.7 years; previous enzyme therapy duration 9.5±4.0 years). Median (range) exposure to miglustat 100 mg t.i.d. was 658 (3–765) days. Twenty-one patients discontinued treatment prematurely; 13 due to adverse events, principally gastrointestinal. The upper 95% confidence limit of mean percent change in liver volume from baseline to end of treatment was below the non-inferiority margin of 10% (–1.1%; 95%CI −6.0, 3.9%). Mean (95%CI) changes in spleen volume, hemoglobin concentration and platelet count were 102 (24,180) mL, –0.95 (−1.38, –0.53) g/dL and −44.1 (–57.6, –30.7) ×10⁹/L, respectively.

Conclusions

The primary efficacy endpoint was met; overall there was no change in liver volume during 24 months of miglustat therapy. Several patients showed a gradual deterioration in some disease manifestations, suggesting that miglustat could maintain clinical stability, but not in all patients. Miglustat demonstrated a predictable profile of safety and tolerability that was consistent with that reported in previous clinical trials and experience in clinical practice.

Trial registration

Clinicaltrials.gov identifier NCT00319046

Endosperm-specific expression of human acid beta-glucosidase in a waxy rice

BACKGROUND

The deficiency of human acid beta-glucosidase (hGCase) causes Gaucher disease, a rare genetically-inherited disorder currently treated by enzyme replacement therapy using recombinant CHO-derived GCase. In an attempt to provide an alternative and more efficient production system, a chimeric cDNA coding for hGCase operatively linked to the signal peptide of rice glutelin 4 (GluB4) was put under the control of the GluB4 endosperm-specific promoter and inserted into the genome of a waxy rice.

RESULTS

Molecular, immunological and biochemical analyses showed that recombinant hGCase, targeted to the protein storage vacuoles of rice endosperm cells, is equivalent to the native protein and has a glycosylation pattern compatible with direct therapeutic use. Compared to a previous study carried out on transgenic tobacco seeds, enzyme contents per unit of biomass were drastically increased; in addition, differently from what observed in tobacco, rice seed viability was unaffected by hGCase even at the highest production level. Transgenic seed polishing combined with a pretreatment of seed flour greatly facilitated hGCase extraction and purification with an industrially-scalable procedure.

CONCLUSIONS

This study opens up the possibility to efficiently produce in the rice seed pharmaceutical compounds which are available in limited amounts or completely excluded from clinical practice due to the inadequacy of their production systems.

Abnormal properties of red blood cells suggest a role in the pathophysiology of Gaucher disease

Gaucher disease (GD) is a lysosomal storage disorder caused by glucocerebrosidase deficiency. It is notably characterized by splenomegaly, complex skeletal involvement, ischemic events of the spleen and bones, and the accumulation of Gaucher cells in several organs. We hypothesized that red blood cells (RBCs) might be involved in some features of GD and studied the adhesive and hemorheologic properties of RBCs from GD patients. Hemorheologic analyses revealed enhanced blood viscosity, increased aggregation, and disaggregation threshold of GD RBCs compared with control (CTR) RBCs. GD RBCs also exhibited frequent morphologic abnormalities and lower deformability. Under physiologic flow conditions, GD RBCs adhered more strongly to human microvascular endothelial cells and to laminin than CTR. We showed that Lu/BCAM, the unique erythroid laminin receptor, is overexpressed and highly phosphorylated in GD RBCs, and may play a major role in the adhesion process. The demonstration that GD RBCs have abnormal rheologic and adhesion properties suggests that they may trigger ischemic events in GD, and possibly phagocytosis by macrophages, leading to the appearance of pathogenic Gaucher cells.

The French Gaucher's disease registry: clinical characteristics, complications and treatment of 562 patients

Background

Clinical features, complications and treatments of Gaucher’s disease (GD), a rare autosomal–recessive disorder due to a confirmed lysosomal enzyme (glucocerebrosidase) deficiency, are described.

Methods

All patients with known GD, living in France, with ≥1 consultations (1980–2010), were included in the French GD registry, yielding the following 4 groups: the entire cohort, with clinical description; and its subgroups: patients with ≥1 follow-up visits, to investigate complications; recently followed (2009–2010) patients; and patients treated during 2009–2010, to examine complications before and during treatment. Data are expressed as medians (range) for continuous variables and numbers (%) for categorical variables.

Results

Among the 562 registry patients, 265 (49.6%) were females; 454 (85.0%) had type 1, 22 (4.1%) type 2, 37 (6.9%) perinatal–lethal type and 21 (3.9%) type 3. Median ages at first GD symptoms and diagnosis, respectively, were 15 (0–77) and 22 (0–84) years for all types. The first symptom diagnosing GD was splenomegaly and/or thrombocytopenia (37.6% and 26.3%, respectively). Bone-marrow aspiration and/or biopsy yielded the diagnosis for 54.7% of the patients, with enzyme deficiency confirming GD for all patients. Birth incidence rate was estimated at 1/50,000 and prevalence at 1/136,000. For the 378 followed patients, median follow-up was 16.2 (0.1–67.6) years. Major clinical complications were bone events (BE; avascular necrosis, bone infarct or pathological fracture) for 109 patients, splenectomy for 104, and Parkinson’s disease for 14; 38 patients died (neurological complications for 15 type-2 and 3 type-3 patients, GD complications for 11 type-1 and another disease for 9 type-1 patients). Forty-six had monoclonal gammopathy. Among 283 recently followed patients, 36 were untreated and 247 had been treated during 2009–2010; 216 patients received treatment in December 2010 (126 with imiglucerase, 45 velaglucerase, 24 taliglucerase, 21 miglustat). BE occurred before (130 in 67 patients) and under treatment (60 in 41 patients) with respective estimated frequencies (95% CI) of first BE at 10 years of 20.3% (14.1%–26.5%) and 19.8% (13.5%–26.1%).

Conclusion

This registry enabled the epidemiological description of GD in France and showed that BE occur even during treatment.

Unexpected cure from cutaneous leukocytoclastic vasculitis in a patient treated with N-butyldeoxynojirimycin (miglustat) for Gaucher disease

Cutaneous leukocytoclastic vasculitis (CLV) is a necrotizing inflammation of the small vessels in the dermis. We report the case of a Swedish man with an untreated N370S/L444P Gaucher disease who developed CLV at the age of 79 years. The patient has been treated for CLV with topical and oral corticosteroids, moisturizing agents, and periodically with antibiotics for 3 years without improvement. Administration of miglustat (N-butyldeoxynojirimycin; Zavesca®) because of progress of Gaucher disease resulted in a prompt and durable cure of the CLV.

Glucocerebrosidase involvement in Parkinson disease and other synucleinopathies

Mutations in both copies (homozygous or compound heterozygous) of the gene encoding the lysosomal enzyme glucocerebrosidase, which cleaves the glycolipid glucocerebroside into glucose and ceramide cause Gaucher disease. However, multiple independent studies have also reported an association between GBA mutations and Parkinsonism with an increased frequency of heterozygous GBA mutations in various cohorts of patients with parkinsonism and other Lewy body disorders. Furthermore, GBA mutation carriers exhibit diverse parkinsonian phenotypes and present a diffuse pattern of Lewy body distribution in the cerebral cortex. This review provides an overview of the genetic basis for this association in various diseases with dysfunction of the central nervous system in which affected individuals developed Parkinsonian symptoms. The emerging clinical, pathological, and genetic studies in neuronal synucleinopathies suggest a common underlying mechanism in the etiology of these neurodegenerative disorders.

Gaucher disease: outcome following total hip replacements and effect of enzyme replacement therapy in a cohort of UK patients

Only a limited number of reports of total hip replacements (THRs) in patients with Gaucher disease (GD) have been published, with the majority showing high rates of early aseptic loosening as well as an increased number of peri-operative complications. We present a series of twelve THRs in nine affected patients, with a mean age of 39 years at the time of surgery (median 37 years; range 27-60 years). We examine the medium- to long-term results and present the outcome scores, survival, and assess the effect of enzyme replacement therapy (ERT). Four hips (33.3%) required revision for aseptic loosening at a mean time of 11.5 years. There was no significant difference in survival between the group on ERT at the time of surgery and group not on ERT. Those on ERT did, however, have fewer peri-operative complications and there was a trend to better outcome scores. Five of the 12 THRs were performed when the diagnosis of GD was unknown and all of these had early complications.?Our results show better survival of THRs in patients with GD than previously thought. The use of ERT pre-operatively did not have an effect on survival, nor outcome scores, but did reduce the peri-operative complication rate. Those not on ERT at the time of surgery were commenced on it at some point in their treatment (at an average of 8.6 years following THR) and we believe the use of ERT, at any time in the treatment, could have contributed to the improved survival seen in our series compared to historical results in the literature.

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

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

[Clinical characteristics of the neurological forms of Gaucher's disease]

Gaucher's disease is the most prevalent disease of accumulation of glycosphingolipids. Neurological involvement is used to classify the different types of the disease. Type 1 affects approximately 90% of patients, and visceral manifestations and bone marrow, without affecting the nervous system. Type 2 is considered a severe form of disease with severe nervous system and death within two years. Type 3 is late, slowly progressive neurological symptoms and survival until the third decade. Besides these classical syndromes, the best knowledge of the disease related to the existence of national registries, the increased survival of patients resulting from replacement therapy, and demonstration of the behavior of glucocerebrosidase mutations as a risk factor of neurodegenerative diseases, has expanded the clinical phenotype and altered the traditional classification of the disease.

Mapping the genetic and clinical characteristics of Gaucher disease in the Iberian Peninsula

Background

Gaucher disease (GD) is due to deficiency of the glucocerebrosidase enzyme. It is panethnic, but its presentation reveals ethnicity-specific characteristics.

Methods

We evaluated the distribution, and clinical and genetic characteristics of GD patients in the Iberian Peninsula (IP). We analysed geographical distribution, demographic, genetic and clinical data, age at diagnosis, type, and years of therapy in 436 GD patients from the IP.

Results

The prevalence of GD was 1/149,000 inhabitants; 88.3% were type 1, 6.7% type 2, and 5.0% type 3. The mean age at diagnosis in type 1 was 28.7 years. A total of 72.7% were classified as having mild forms, 25.5% moderate, and 1.7% severe. Anemia and thrombocytopenia were present in 56% and 55%, respectively. Bone disease and hepatomegaly were reported in 62% and 68%, respectively, and were more likely in asplenic than in non-splenectomized patients. Sixty-nine mutant alleles were identified, and five mutations accounted for 75% of the GBA alleles. Several patients described in our series had interesting phenotypes. A total of 58.7% of patients had received enzyme replacement therapy and 12.6% were treated with miglustat.

Conclusions

A broad spectrum of GBA mutations is present in the IP, with 98.2% of type 1 GD being mild and 23.0% never treated. These data highlight genetic and phenotypic heterogeneities among geographic populations.

[Therapeutic targets in Gaucher's disease]

Gaucher's disease (GD) occurs because of deficiency of the enzyme beta-glucocerebrosidase that results in accumulation of this glycolipid compound in the cells of the macrophage-monocyte system. There are 3 types: type 1 is non-neuronopathic with primarily visceral signs and symptoms which range tremendously in severity; infantile-onset type 2 and later-onset type 3 involve the central nervous system. More than 300 mutations have been described in the gene, partially explaining phenotypic heterogeneity. Commercialization in 1991 of the first enzyme replacement therapy, alglucerase, resulted in a revolution in the management of patients with symptomatic GD (i.e., by improving the hematological and visceral signs and symptoms). Within the first 5 years of alglucerase, its safety and efficacy in improving hemoglobin levels and platelet counts, and in reducing splenic and hepatic enlargement were confirmed albeit recognizing its inability to impact neurological symptoms and signs because of its large molecular size. Recombinant imiglucerase soon replaced alglucerase as the standard of care for GD. The therapeutic targets recently defined as treatment goals were: normalization of cell counts; reduction of liver and spleen volume; elimination of the infiltration in the bone marrow to prevent the complications, and improvement in surrogate biomarkers.

Gaucher's disease: the changing paradigm of a lysosomal disorder

Gaucher's disease (GD) is the most common lysosomal storage disease with a frequency of approximately 1:50,000 people. It is the result of the deficiency of the lysosomal enzyme beta-glucocerebrosidase. The deficiency of the enzyme results in the accumulation of the substrate, glucosyl-ceramide, in the organs. Substitutive enzymatic treatment has been available since almost 20 years. This brief overview highlights some of the most important milestones and the treatments for this disease. The study of this rare disorder is beginning to provide information on the pathogenesis of common diseases such as Parkinson's disease or cancer. Individuals with GD are at greater risk of developing cancer in general, especially hepatobiliary and hematologic (multiple myeloma and B-cell neoplasms). This association has been attributed to the immunologic abnormalities associated with abnormal expression of cytokines such as interleukin-6. Alternative and complementary, some recently marketed and licensed, are providing options for patients throughout Europe and the world.

The cellular pathology of lysosomal diseases

With a constitutive recycling function and the capacity to digest exogenous material as well as endogenous organelles in the process of autophagy, lysosomes are at the heart of the living cell. Dynamic interactions with other cellular components ensure that the lysosomal compartment is a central point of convergence in countless diverse diseases. Inborn lysosomal (storage) diseases represent about 70 genetically distinct conditions, with a combined birth frequency of about 1 in 7500. Many are associated with macromolecular storage, causing physical disruption of the organelle and cognate structures; in neurons, ectopic dendritogenesis and axonal swelling due to distension with membraneous tubules and autophagic vacuoles are observed. Disordered autophagy is almost universal in lysosomal diseases but biochemical injury due to toxic metabolites such as lysosphingolipid molecules, abnormal calcium homeostasis and endoplasmic reticulum stress responses and immune-inflammatory processes occur. However, in no case have the mechanistic links between individual clinico-pathological manifestations and the underlying molecular defect been precisely defined. With access to the external fluid-phase and intracellular trafficking pathways, the lysosome and its diseases are a focus of pioneering investment in biotechnology; this has generated innovative orphan drugs and, in the case of Gaucher's disease, effective treatment for the haematological and visceral manifestations. Given that two-thirds of lysosomal diseases have potentially devastating consequences in the nervous system, future therapeutic research will require an integrative understanding of the unitary steps in their neuro pathogenesis. Informative genetic variants illustrated by patients with primary defects in this organelle offer unique insights into the central role of lysosomes in human health and disease. We provide a conspectus of inborn lysosomal diseases and their pathobiology; the cryptic evolution of events leading to irreversible changes may be dissociated from the cellular storage phenotype, as revealed by the outcome of therapeutic gene transfer undertaken at different stages of disease.

Biomarkers for osteonecrosis in Gaucher disease

INTRODUCTION

The search for surrogate biomarkers of osteonecrosis, a disabling complication of Gaucher disease, has intensified in the last decade. Biomarkers that predict osteonecrosis and monitor the effectiveness of therapies would improve clinical practice and enrich the molecular exploration of this disorder.

AREAS COVERED

Here we discuss advances in biomarker research with special reference to those biomarkers associated with Gaucher disease and investigated in the context of enzyme therapy. Much progress has been made in the diversification of treatment for the condition and several biomarker molecules, which may ultimately improve risk assessment for osteonecrosis, have been identified.

EXPERT OPINION

The discovery of prospective biomarkers of osteonecrosis such as CCL18/PARC, CXCL8/IL-8, CCL5/RANTES, CCL3/MIP-1α, CCL4/MIP-1β, particularly during recurrent episodes occurring despite enzyme treatment, has the potential radically to change practices in the management of Gaucher disease and should improve therapeutic monitoring and prognostic evaluation. Ultimately, exploration of this field will provide the basis for a refined mechanistic understanding of pathogenesis.

Radiological aspects of Gaucher disease

Advances in imaging and the development of commercially available enzyme therapy have significantly altered the traditional radiology of Gaucher disease. The cost of treatment and need for monitoring response to therapy have magnified the importance of imaging. There are no recent comprehensive reviews of the radiology of this relatively common lysosomal storage disease. This article describes the modern imaging, techniques and radiological manifestations of Gaucher disease.

Synchronous presentation of Gaucher disease and solitary plasmacytoma with progression to multiple myeloma

A 37-year-old Polish immigrant presented with unilateral hip pain and difficulty weight-bearing. Plain radiography and magnetic resonance imaging (MRI) revealed a lytic lesion in the acetabulum, with abnormal serum electrophoresis and bone marrow biopsy. The patient was diagnosed with two rare conditions presenting synchronously – Gaucher disease and plasmacytoma. He was treated with enzyme therapy and radiotherapy, but subsequently developed a recurrence of plasmacytoma in the right femur, confirmed with bone marrow biopsy. This was also treated with radiotherapy, followed by a retrograde femoral nail to reduce the risk of pathological fracture. The patient went on to develop multiple lytic lesions in the ribs and vertebra, seen on MRI. Further bone marrow biopsy confirmed dissemination of the plasmacytoma into multiple myeloma, for which he was treated with systemic chemotherapy. In patients presenting with refractory bone or joint pain, haematological and histological investigations should be considered to exclude less common diagnoses.

A reappraisal of Gaucher disease-diagnosis and disease management algorithms

Type 1 (non-neuronopathic) Gaucher disease was the first lysosomal storage disorder for which an effective enzyme replacement therapy was developed and it has become a prototype for treatments for related orphan diseases. There are currently four treatment options available to patients with Gaucher disease, nevertheless, almost 25% of Type 1 Gaucher patients do not gain timely access to therapy because of delays in diagnosis after the onset of symptoms. Diagnosis of Gaucher disease by enzyme testing is unequivocal, but the rarity of the disease and nonspecific and heterogeneous nature of Gaucher disease symptoms may impede consideration of this disease in the differential diagnosis. To help promote timely diagnosis and optimal management of the protean presentations of Gaucher disease, a consensus meeting was convened to develop algorithms for diagnosis and disease management for Gaucher disease.

Gaucher disease: clinical profile and therapeutic developments

Gaucher disease is a rare inborn error of glycosphingolipid metabolism due to deficiency of lysosomal acid β-glucocerebrosidase; the condition has totemic significance for the development of orphan drugs. A designer therapy, which harnesses the mannose receptor to complement the functional defect in macrophages, ameliorates the principal clinical manifestations in hematopoietic bone marrow and viscera. While several aspects of Gaucher disease (particularly those affecting the skeleton and brain) are refractory to treatment, enzyme (replacement) therapy has become a pharmaceutical blockbuster. Human β-glucocerebrosidase was originally obtained from placenta and the Genzyme Corporation (Allston, MA) subsequently developed a recombinant product. After purification, the enzyme is modified to reveal terminal mannose residues which facilitate selective uptake of the protein, imiglucerase (Cerezyme^®), in macrophage-rich tissues. The unprecedented success of Cerezyme has attracted fierce competition: two biosimilar agents, velaglucerase-alfa, VPRIV^® (Shire Human Genetic Therapies, Dublin, Ireland) and taliglucerase-alfa (Protalix, Carmiel, Israel), are now approved or in late-phase clinical development as potential ‘niche busters’. Oral treatments have advantages over biological agents for disorders requiring lifelong therapy and additional stratagems which utilize small, orally active molecules have been introduced; these include two chemically distinct compounds which inhibit uridine diphosphate glucose: N-acylsphingosine glucosyltransferase, the first step in the biosynthesis of glucosylceramide – a key molecular target in Gaucher disease and other glycosphingolipidoses. Academic and commercial enterprises in biotechnology have combined strategically to expand the therapeutic repertoire in Gaucher disease. The innovative potential of orphan drug legislation has been realized – with prodigious rewards for companies embracing its humanitarian precepts. In the era before enzyme therapy, bone marrow transplantation was shown to correct systemic disease in Gaucher patients by supplying a source of competent donor macrophages. As a radical advance on cell- or protein-replacement techniques, contemporary methods for transferring genes to autologous hematopoietic stem cells, and to the brain, merit further exploration. At present, the inflated pharmaceutical niche of Gaucher disease appears to be resilient, but if the remaining unmet needs of patients are to be convincingly addressed and commercial development sustained, courageous scientific investment and clinical experimentation will be needed.

Peripheral neuropathy in adult type 1 Gaucher disease: a 2-year prospective observational study

Type 1 Gaucher disease is currently categorized as non-neuronopathic, although recent studies suggest peripheral neurological manifestations. We report prevalence and incidence data for peripheral neuropathy and associated conditions from a multinational, prospective, longitudinal, observational cohort study in patients with type 1 Gaucher disease, either untreated or receiving enzyme replacement therapy. The primary outcome parameters were the prevalence and incidence of polyneuropathy, evaluated by standardized assessments of neurological symptoms and signs, and electrophysiological studies. All diagnoses of polyneuropathy were adjudicated centrally. Secondary outcome parameters included the prevalence and incidence of mononeuropathy, other neurological or electrophysiological abnormalities not fulfilling the criteria for a mono- or polyneuropathy and general type 1 Gaucher disease symptoms. Furthermore, a literature search was performed to identify all studies reporting on prevalence and incidence of polyneuropathy in the general population. One hundred and three patients were enrolled [median (range) age: 42 (18-75) years; disease duration: 15 (0-56) years; 52% female]; 14 (13.6%) were untreated and 89 (86.4%) were on enzyme replacement therapy. At baseline, 11 patients [10.7%; 95% confidence interval (CI): 5.9-18.3] were diagnosed with sensory motor axonal polyneuropathy. Two (1.9%; 95% CI: 0.1-7.2) had a mononeuropathy of the ulnar nerve. The 2-year follow-up period revealed another six cases of polyneuropathy (2.9 per 100 person-years; 95% CI: 1.2-6.3). Patients with polyneuropathy were older than those without (P<0.001). Conditions possibly associated with polyneuropathy were identified in four patients only, being monoclonal gammopathy, vitamin B(1) deficiency, folic acid deficiency, type 2 diabetes mellitus, renal insufficiency, alcohol abuse and exposure to toxins related to profession. The 11 cases of polyneuropathy found at baseline were confirmed during follow-up. According to the literature, the prevalence of polyneuropathy in the general population was estimated between 0.09 and 1.3% and the incidence was estimated between 0.0046 and 0.015 per 100 person-years. Thus, we conclude that the prevalence and incidence of polyneuropathy in patients with type 1 Gaucher disease is increased compared with the general population.

Hyperferritinemia and iron overload in type 1 Gaucher disease

Hyperferritinemia occurs in Gaucher disease but its clinical spectrum or its association with systemic iron overload and HFE mutations are not known. In 114 patients with Type 1 Gaucher disease, we determined serum ferritin, transferrin saturation and HFE genotype. The results were correlated with the extent of hepatosplenomegaly, overall Gaucher disease severity score index, and response to enzyme replacement therapy. In a subset of patients with radiological and/or laboratory evidence of systemic iron overload, liver biopsy was performed. There was a mean 3.7-fold elevation of serum ferritin over the upper limit of normal (ULN). Prior splenectomy was associated with most severe hyperferritinemia compared to patients with intact spleen (6.53 x ULN vs. 2.69 x ULN, P = 0.003). HFE genotyping revealed two patients homozygous for H63D mutation and 30% of patients heterozygote carriers of H63D mutation; no patients harbored C282Y mutation; there was no correlation of ferritin with HFE genotype. Ferritin level correlated with liver volume (Pearson correlation coefficient = 0.254, P = 0.035) and it was negatively correlated with hemoglobin (r = -0.315, P = 0.004); there was no relationship with other indicators of Gaucher disease activity. Enzyme replacement therapy (ERT) resulted in amelioration of hyperferritinemia: 707 +/- 898 ng/ml vs. 301 +/- 310 ng/ml (P = 0.001), transferrin saturation remained normal. Three patients were suspected of clinical iron overload, confirmed on liver biopsy. Iron accumulation was variably noted in hepatocytes and Kupffer cells. There is a high prevalence of hyperferritinemia in Type 1 Gaucher disease that is associated with indicators of disease severity, reversed by ERT and is not related to HFE mutations.

High incidence of cholesterol gallstone disease in type 1 Gaucher disease: characterizing the biliary phenotype of type 1 Gaucher disease

BACKGROUND

In Gaucher disease (GD), lysosomal glucocerebrosidase deficiency results in glucosylceramide accumulation in macrophage lysosomes. Hepatocytes do not accumulate glucosylceramide due in part to biliary secretion. Although gallstones (GS) occur in type 1 Gaucher disease (GD1), the chemical nature of stones, their association with metabolic parameters, and whether bile composition is altered are not understood. We assessed the prevalence of GS, their chemical composition, biliary lipids, and associated metabolic factors.

METHODS

The study cohort comprised 417 patients comprehensively evaluated for GD1 severity. Ascertainment of GS, fasting lipoprotein profile, and bile lipid analyses were performed.

RESULTS

The prevalence of GS in GD1 was 32%. Compared with men, the prevalence of GS was higher in women, increasing from 4.2% and 11.8% at age 20-29 years to 71% and 60% at age >70 years, respectively. Patients with GS were more likely to be asplenic (p < 0.0001), older (p < 0.0001), have higher low-density lipoprotein (LDL) cholesterol (p = 0.002), and more severe GD1 disease compared with those without GS. On multiple logistic regression analysis, factors associated with GS were age (p < 0.001), female sex (p = 0.03), and splenectomy (p = 0.005). Compared with the general population, prevalence of GS was approximately 5-fold higher. Bile lipid analyses revealed cholesterol stones in five patients and pigment stones in one. Bile lipid composition was abnormal and contained glucosylceramide.

CONCLUSIONS

Our results point to a metabolic syndrome in GD1 consisting of a propensity to cholesterol GS, low high-density lipoprotein (HDL) cholesterol, LDL cholesterol, and body mass index (BMI) associated with abnormal biliary lipid secretion.

Expanding spectrum of the association between Type 1 Gaucher disease and cancers: a series of patients with up to 3 sequential cancers of multiple types--correlation with genotype and phenotype

In Gaucher disease (GD), inherited deficiency of lysosomal glucocerebrosidase due to mutations in GBA1 gene results in accumulation of glucosylceramide in tissue macrophages, systemic macrophage activation, and a complex multisystemic phenotype. We and others have reported an increased risk of multiple myeloma and other malignancies in non-neuronopathic Type 1 GD (GD1). Here, we describe a subset of GD1 patients with multiple malignancies. In our cohort of 403 patients with GD1, nine patients (2.2%) developed two or three different types of cancers either consecutively or simultaneously. Patients were characterized by age at diagnosis of GD1, GBA1 genotype, disease severity, age at cancer diagnosis, enzyme replacement therapy (ERT) status, and splenectomy status. Of the nine patients, six developed two types of malignancies and three had three cancers each. Overall, the hematologic malignancies comprised lymphoma/leukemia (4) and multiple myeloma (4). Nonhematologic malignancies included colon (2), lung (2), thyroid (2), and prostate cancer (1). Of the seven patients who received ERT, the first cancer was diagnosed before initiation of ERT in all but one. Asplenic patients were more likely to have single or multiple cancers compared with patients with intact spleens (P < 0.0072 and P < 0.0203, respectively). Our data strengthen the association of GD1 and cancer and suggest that patients may be at risk of developing multiple malignancies. We found an association between splenectomy and multiple cancers in GD1. It will be of interest to determine whether timely ERT and declining rates of splenectomy will translate into declining rates of multiple and single cancers.

Glucocerebrosidase as a genetic modifier influencing susceptibility and phenotype of Parkinson’s disease

Evaluation of: Sidransky E, Nalls MA, Aasly JO et al.: Multicenter analysis of glucocerebrosidase mutations in Parkinson’s disease. N. Engl. J. Med. 361, 1651–1661 (2009). This study aimed to substantiate the role of glucocerebrosidase (GBA) mutations in Parkinson’s disease (PD) by pooling clinical and genotypic data for 5691 PD patients and 4898 unaffected individuals from 16 international centers. Genotyping was performed for either two mutations (N370S and L444P) or for three to eight GBA mutations. One of the N370S and L444P mutations was found in 15 and 3% of PD patients of Ashkenazi and non-Ashkenazi Jewish origin, respectively. Whole gene sequencing performed in a subgroup of these patients revealed a combined odds ratio of carrying any GBA mutation of 5.43. Genotype–phenotype correlations verified that GBA mutation carriers were more likely to develop PD at an earlier age, have affected relatives and show increased incidence of cognitive changes compared with PD patients without mutations. This study provides evidence that heterozygosity for GBA mutations is the most common susceptibility factor for the onset of PD symptoms to date. It also highlights the need for further studies using large numbers of patients and controls in order to elucidate the effect(s) of GBA mutations on PD clinical manifestations and their role in the molecular mechanisms of PD pathogenesis.

Force majeure: therapeutic measures in response to restricted supply of imiglucerase (Cerezyme) for patients with Gaucher disease

Gaucher disease is the first lysosomal disorder for which clinically effective enzyme replacement therapy has been introduced. Lifelong treatment with imiglucerase, the recombinant glucocerebrosidase manufactured by the Genzyme Corporation (MA, USA), is administered intravenously - usually at biweekly intervals. An acute shortage of imiglucerase (to 20% of prior global supply) has occurred as a result of viral contamination of the production facility; production was halted, and a full supply of imiglucerase is not anticipated until January 2010. An urgent meeting of physicians, researchers, and patients was convened through the agency of the European Working Group for Gaucher Disease; this was instigated by patients internationally represented by the European Gaucher Alliance. Here we present a position statement based on the findings of the group, with key recommendations about identification and monitoring of at-risk patients threatened by the abrupt withdrawal of treatment, the equitable distribution of residual imiglucerase - and access to alternative treatments including those that have completed phase III clinical trials but have not yet been licensed.

Timing of initiation of enzyme replacement therapy after diagnosis of type 1 Gaucher disease: effect on incidence of avascular necrosis

Data from the International Collaborative Gaucher Group Gaucher Registry were analysed to assess the relationship between enzyme replacement therapy with imiglucerase (ERT) and incidence of avascular necrosis (AVN) in type 1 Gaucher disease (GD1), and to determine whether the time interval between diagnosis and initiation of ERT influences the incidence rate of AVN. All patients with GD1 enrolled in the Gaucher Registry who received ERT and did not report AVN prior to starting therapy (n = 2700) were included. The incidence rate of AVN following initiation of ERT was determined. An incidence rate of AVN of 13·8 per 1000 person-years was observed in patients receiving ERT. Patients who initiated ERT within 2 years of diagnosis had an incidence rate of 8·1 per 1000 person-years; patients who started ERT ≥2 years after diagnosis had an incidence rate of 16·6 per 1000 person-years. The adjusted incidence rate ratio was 0·59 [95% confidence interval (CI) 0·36–0·96, P = 0·0343]. Splenectomy was an independent risk factor for AVN (adjusted incidence rate ratio 2·23, 95% CI 1·61–3·08, P < 0·0001). In conclusion, the risk of AVN was reduced among patients who initiated ERT within 2 years of diagnosis, compared to initiating treatment ≥2 years after diagnosis. A higher risk of AVN was observed among patients who had previously undergone splenectomy.