Gaucher disease and the clinical experience with substrate reduction therapy

Gaucher disease is caused by an enzymatic defect with consequent accumulation of glucocerebroside. Type I, the non-neuronopathic form, is rather common and panethnic. Patients may present with hepatosplenomegaly, anaemia, thrombocytopenia and skeletal or lung involvement. Enzyme replacement therapy ameliorates disease symptoms and signs; however, it involves lifelong intravenous therapy, is costly and is incapable of crossing the blood-brain barrier. Substrate reduction with N-butyldeoxynojirimycin (OGT 918) is a harbinger of oral iminosugars for glycolipid storage disorders. Long-term data in the seminal trial (100 mg three times per day), demonstrate safety and efficacy in adult type I patients naive to enzyme therapy, and suggest its application in patients unwilling or unable to receive enzyme replacement and tolerating side effects, including diarrhoea, weight loss, tremor and peripheral neuropathy (mostly reversible with dose reduction or withdrawal). Dose dependency was demonstrated with 50 mg three times per day. In patients stabilized on enzyme therapy switched from or in combination with enzyme, no deterioration in disease parameters was seen but side effects were as above. Although efficacy is less dramatic than enzyme treatment, it may be that plateaux are achieved asymptotically so therapeutic outcomes with OGT 918 may ultimately be comparable. Yet, given the above side effects and the lack of long-term experience, patients with very mild manifestations would probably not be appropriate candidates.

Gaucher disease: pediatric concerns

Gaucher disease, the most prevalent lysosomal storage disorder, is inherited as an autosomal recessive condition. The gold standard for diagnosis is decreased acid beta-glucosidase activity in the lymphocytes or fibroblasts; molecular analysis of mutations allows for some prognostication of disease severity. Prenatal diagnosis and carrier testing for at-risk families are currently available. There is tremendous phenotypic heterogeneity in the non-neuronopathic form (type I), ranging from clinically asymptomatic to massive hepatomegaly, hypersplenism, growth retardation in children and extensive involvement of bone and lungs. Presence on one allele of the most common mutation, N370S, which is the most prevalent among Ashkenazi Jews for whom there is a predilection for Gaucher disease, is protective of neurological involvement. Some mutations, such as 84GG and IVS2+1, are associated with more severe disease manifestations when appearing as compound heterozygotes with N370S, but when occurring in the homozygous state are not compatible with life. Other mutations, such as L444P, are associated with severe non-neurological disease when occurring as compound heterozygotes with N370S, but when occurring in the homozygous state may be predictive of neurological disease of either acute (type II) or subacute (type III) forms. In the past decade, enzyme replacement therapy has become available which has resulted in a reduction in liver and spleen volume and consequently improved anemia and thrombocytopenia in most patients. It has also engendered catch-up growth in many children, induced improvement in lung involvement secondary to Gaucher disease, and to some extent ameliorated episodes of bone pain. By virtue of treatment, many children who may have been severely affected no longer need to undergo splenectomy to treat hypersplenism, and therefore they are not at risk of bone involvement consequent to the loss of the preferred reservoir for lipid-laden 'Gaucher cells'. However, enzyme treatment is ineffective in reversing neurological signs, requires a lifelong commitment to intravenous infusions, thereby reducing quality of life, and is relatively expensive for many national health schemes. Hence, alternative forms of treatment, such as substrate balance, are being explored. Symptomatic management, including orthopedic surgery, pain relief for bone pain and even splenectomy, still has importance for patients with Gaucher disease. In addition, there is the potential for bone marrow transplantation and, in the future, gene therapy to be curative, particularly for patients with the neuronopathic forms.

The role of the iminosugar N-butyldeoxynojirimycin (miglustat) in the management of type I (non-neuronopathic) Gaucher disease: a position statement

N-Butyldeoxynojirimycin (NB-DNJ, miglustat 'Zavesca') is an orally active iminosugar which inhibits the biosynthesis of macromolecular substrates that accumulate pathologically in glycosphingolipidoses. Clinical trials of NB-DNJ in patients with Gaucher's disease demonstrate the therapeutic potential of such substrate inhibitors in the glycolipid storage disorders. However, macrophage-targetted enzyme replacement using intravenous mannose-terminated human glucocerebrosidase (imiglucerase, Cerezyme) is highly effective in ameliorating many of the manifestations of Gaucher's disease and is a treatment in widespread use. Given that imiglucerase and miglustat are now both licensed for the treatment of Gaucher's disease, there is a need to review their therapeutic status. Here the treatment of type 1 (non-neuronopathic) Gaucher disease is evaluated with particular reference to the emerging role of oral N-butyldeoxynojirimycin (miglustat) as a substrate-reducing agent. This position statement represents the consensus viewpoint of an independent international advisory council to the European Working Group on Gaucher Disease.

Fluorescent flow cytometric assay: a new diagnostic tool for measuring beta-glucocerebrosidase activity in Gaucher disease

The purpose of this study was to determine glucocerebrosidase activity by a fluorescent flow cytometry method in patients and carriers of Gaucher disease, and in healthy controls, and correlate the results with the standard glucocerebrosidase assay in the same individuals. Biochemical diagnosis has heretofore been performed by measuring enzyme activity using a fluorimetric assay method with cell lysate. We present the results of a quantitative fluorescence-activated cell sorter (FACS) assay for diagnosis of Gaucher disease. Twenty-eight patients, 15 obligate carriers, and 21 healthy controls were tested by both the standard and FACS methods. Fluorescent products were obtained by intracellular hydrolysis of fluorescein di-beta-glucopyranoside and measured by fluorescent flow cytometer. Activity was then expressed as an index ratio of mean fluorescence of the patient sample relative to control. Specificity of the assay for lysosomal beta-glucocerebrosidase was demonstrated using conditurol-beta-epoxide (CBE), a specific irreversible inhibitor of beta-glucocerebrosidase. Both methods were performed on blood samples without knowledge of the genetic results. The mean +/- SD results using FACS were: controls 1.12 +/- 0.26, patients with Gaucher disease 0.21 +/- 0.09 and carriers 0.76 +/- 0.15. Using the standard method, mean enzyme activities were: controls 35.7 +/- 9.0 uU/mg protein, patients with Gaucher disease 8.4 +/- 4.5 uU/mg protein, and carriers 32.2 +/- 6.9 uU/mg protein. Thus, FACS is a reliable and easy to use method for determination of enzyme activity in Gaucher disease, with excellent correlation with the standard method. The FACS method allows single cell enzyme evaluation rather than global activity of cell lysate, and gives excellent separation between patients, carriers, and controls.

Decreased salivary output in patients with Gaucher disease

BACKGROUND

Gaucher disease, the most common sphingolipid storage disease, results in accumulation of glucocerebroside in macrophages or "Gaucher cells". In a preliminary screening of 109 patients with type I disease, when asked specifically about dry mouth, approximately one quarter claimed to suffer from this symptom.

AIM

To ascertain whether decreased salivary output is a feature of Gaucher disease.

DESIGN

Prospective case-control study.

METHODS

Salivary output was measured in 65 adult patients and 65 healthy controls using the Saxon test with Hochberg's modification.

RESULTS

Mean salivary output was 1.91+/-1.19 g/min in the patient group vs. 2.74+/-1.17 g/min in the control group (p<0.001). This difference was greater among males. These results were not improved in the patients receiving enzyme replacement therapy, which is effective in ameliorating most Gaucher-related signs and symptoms.

DISCUSSION

Recent studies have implicated an association between sicca syndrome and viral hepatitis C infection, which may imply an immunological trigger for these findings, but in this specific cohort, only three patients were reactive for hepatitis C. Follow-up of patients, both untreated and receiving enzyme therapy, is needed to delineate the association with salivary hypofunction, and ascertain whether enzyme therapy may induce sicca symptoms.

Thrombocytosis associated with enzyme replacement therapy in Gaucher disease

We describe a patient with an intact spleen and moderately severe symptoms of Gaucher disease in whom, after initiation of (low-dose) enzyme replacement therapy (ERT), thrombocytosis (720 x 10(9)/l) was documented. Checking the International Gaucher Registry database revealed that this patient is the only nonsplenectomized patient of more than 1,000 treated patients to experience ERT-induced thrombocytosis. Platelet counts dropped immediately after the discontinuation of ERT.

Multiple hypoechoic hepatic lesions in a patient with Gaucher disease

The most common symptoms of Gaucher disease include hepatosplenomegaly and anemia and thrombocytopenia due to hypersplenism. We describe the case of a patient with Gaucher disease who had cachexia, massive hepatomegaly, and multiple focal hepatic lesions. The clinical and radiologic findings suggested malignancy. A biopsy specimen was taken from a hepatic lesion and revealed infiltration by Gaucher cells. We discuss our findings in light of the putative increased incidence of hematologic malignancies in patients with Gaucher disease.

Type I Gaucher disease in children with and without enzyme therapy

This retrospective study describes the course of 56 children with non-neuronopathic Gaucher disease who presented at <16 years and were followed at 6- to 12-month intervals for 3-9 years. Massive splenomegaly and height retardation marked those who required treatment. Enzyme replacement significantly increased hemoglobin levels; platelet counts were divergent at presentation and follow-up, regardless of therapy. Among treated patients there was a significant reduction in liver and spleen index volumes, and a significant increase in height z-scores. None of the children required splenectomy or developed lung involvement. Many patients diagnosed due to large-scale screening were very mildly affected and remain untreated.

Plasma chitotriosidase activity in patients with beta-thalassemia

Variable increases in chitotriosidase levels have been reported in Italian patients with beta-thalassemia major and intermedia. We measured plasma chitotriosidase levels in Israeli patients with beta-thalassemia to ascertain its use as a universal marker of disease and/or response to therapy. Chitotriosidase levels in 39 adults (16-53 years; 30 with beta-thalassemia major, 9 with intermedia), and in 14 children (0.7-15 years; 12 with beta-thalassemia major, 2 with intermedia) were compared with other measures of disease, such as ferritin, hemoglobin, liver function tests, and genotype. Plasma chitotriosidase levels were normal (0.37 +/- 0.04 mU/mL) in all children. Twelve adults (31%) had elevated levels (>1.33 mU/mL): 11 patients (37%) with thalassemia major and 1 patient (11%) with thalassemia intermedia. A significant correlation was only found between plasma chitotriosidase levels and ferritin levels, and with mean number of transfusions per year. The patient with the highest chitotriosidase (1,440 nmol/mL/hr) had the highest ferritin (5,175 microg/L), required the most transfusions per year (40), and had abnormal liver tests. Normal chitotriosidase levels in the pediatric cohort and increased levels in only some adults may reflect status of iron overload in macrophages; thus there may be a role for monitoring chitotriosidase in patients with beta-thalassemia. Our results confirm results of the Italian cohort; however, in the latter, a more universal correlation was noted and chitotriosidase levels were much higher.

Tc-99m sestamibi bone marrow scintigraphy in Gaucher disease

PURPOSE

No imaging technique has been found to be adequate to assess the severity and extent of bone involvement in patients with Gaucher disease. Marrow involvement, as determined by Tc-99m sulfur colloid, correlated well with the clinical and radiologic changes of the skeleton, but a normal pattern was found in the early stages of the disease. Subsequently, Tc-99m sestamibi (MIBI) has been suggested for direct visualization of glycolipid deposits in the bone marrow. This study was initiated as a pilot using MIBI to detect various forms of bone disease in patients with Gaucher disease of varying severity.

MATERIALS AND METHODS

Eleven patients (9 men; median age, 39.9; age range, 21 to 61 years) were evaluated. The clinical severity of disease was scored at presentation, and four patients with moderate to severe disease were treated with enzyme replacement therapy. Each patient underwent a radiographic skeletal survey, bone densitometry, and MIBI scintigraphy. The scan included static images of the lower limbs, with a whole-body scan acquired between the early and late acquisition. Tracer uptake in the bone marrow was graded and correlated with clinical and objective variables.

RESULTS

All but one patient had increased MIBI uptake in the bone marrow. No correlation was noted between MIBI uptake and severity score, radiographic changes, densitometry z score, or treatment status.

CONCLUSIONS

MIBI scanning is a sensitive technique for detecting bone marrow deposits in Gaucher disease, but it is inadequate for early identification of patients at high risk for skeletal complications or for the follow-up of patients treated with enzyme replacement.

Chitotriosidase deficiency in survivors of Candida sepsis

The existence of chitotriosidase, a human chitinolytic enzyme, hydrolyzes artificial chitotrioside substrates, but its specific function in humans is unknown. The homologous chitinases have an anti-fungal action in plants. In patients with Gaucher disease, chitotriosidase activity is markedly elevated and is a marker for response to specific treatment. In all populations, 6% of individuals are enzyme deficient but completely healthy. It was hypothesized that chitotriosidase deficient persons may be more vulnerable to fungal infections. Thus, the objective of the study was to ascertain the prevalence of homozygosity for the mutation of chitotriosidase among survivors of Candida sepsis. The prevalence of homozygosity among survivors was similar to that in the normal population. Although the cohort is the largest of its kind, since only survivors were tested, further studies should include all patients with Candida sepsis for comparison of survival rates among deficient versus sufficient individuals, and thereby elucidate if this enzyme has an anti-fungal function in man. Several theories are considered to explain the results.

C7 complement deficiency in an Israeli Arab village

Deficiencies of terminal complement components, particularly the latter ones, are often detected because of increased susceptibility to Neisserial infections. Herein we document the first report of C7 deficiency among a highly inbred Arab population living in the lower Galilee region of Israel. Both biochemical and molecular analysis were performed on samples from infected survivors and parents of children who succumbed to Neisserial infections in a 4-year period. Only the index case who suffered recurrent infections and a sibling who had not suffered an infection during the outbreak were found to be C7-deficient. The mutation was found to be the one previously described to be prevalent among Israeli Jews of Moroccan ancestry (mutation G1135C). The implications of this finding are discussed in the context of family pedigree, the protective effect of complement deficiency, and the clinical outcome.

Low-dose N-butyldeoxynojirimycin (OGT 918) for type I Gaucher disease

The objective of this study was to evaluate the efficacy and safety of low-dose substrate balance therapy with OGT 918 for the treatment of adults with Gaucher disease. Eighteen patients with Gaucher disease from two centers were enrolled in an open-label 6-month study of OGT 918, 50 mg taken three times daily (TID), followed by an optional extended-use phase. Changes in liver and spleen volume at 6 and 12 months, as well as routine hematological and biochemical parameters on a monthly basis, were evaluated. During the extension, dosage was increased to 100 mg TID in patients in one center to improve the response. Seventeen patients completed 6 months; of 16 patients in the extension phase, 13 were evaluable at 12 months. Percentage changes in liver (-5.9%, P = 0.007) and spleen (-4.5%, P = 0.025) volumes and in chitotriosidase levels (-4.6%, P = 0.039) at 6 months were commensurately lower than those reported previously in an open-label trial using 100 mg TID; hemoglobin and platelet counts were not boosted. At 12 months there were further mean decreases from baseline in liver volume (-6.2%, P = 0.037), spleen volume (-10.1%, P < 0.05), and chitotriosidase levels (-15.3%, P < 0.05) as well as mean changes of +1.2 and +14.7% in hemoglobin and platelet concentrations, respectively [correction]. There were no serious adverse effects throughout the 6-month study period; common side effects were diarrhea (94%) and weight loss (67%), comparable to the incidence in the original trial. We conclude that OGT 918 was safe and effective at 50 mg TID, but shows dose dependency in ameliorating parameters of Gaucher disease relative to the results noted in the seminal trial; there was no improvement in the rate of hematological response and no reduction in side effects. Results from the extension wherein some patients were dose increased suggest that 100 mg TID should be the preferred starting regimen for patients with symptomatic type I Gaucher disease.

Spectrum of abdominal sonographic findings in 103 pediatric patients with Gaucher disease

The purpose of this study was to catalogue spleen and liver features by US in a cohort of 103 pediatric patients with Gaucher disease, and to document response to enzyme replacement therapy by serial US examination. There were 42 boys and 61 girls, 2 were splenectomized. Forty-eight patients received enzyme replacement therapy (ERT). At presentation all patients evinced organomegaly and 4.9% had focal (splenic or hepatic) lesions (hypo- and hyper-echoic or mixed). Fifteen patients began ERT before 11 years of age. There was a mean liver volume reduction from 230 to 137% after 2 years of ERT, with further reduction of 91% up to 6 years later. Mean spleen volume reduction was 38.4% at 2 years of ERT and a further reduction to 40.8% at last evaluation. Fourteen children began ERT between ages 11 and 16 years. Mean liver reduction was from 230 to 124% at 2 years and further reduction to mean of 104% recently. Mean splenic reduction was 37.7% after 2 years of ERT, with a mean of 43.8% recently (mean 4.5 years later). Organ volume changes in untreated and treated children were documented by US which is the modality of choice for repeat measures in this population. Our results highlight the initial dramatic and then continued response to ERT in pediatric patients with Gaucher disease.

High prevalence of low serum vitamin B12 in a multi-ethnic Israeli population

This study ascertained serum vitamin B12 levels among patients with Gaucher disease and among healthy Israelis. Serum B12 and metabolites' levels were studied in consecutive adult patients with Gaucher disease not treated with enzyme plus Ashkenazi Jewish neighbour-controls, together with healthy blood-donor volunteers of various ethnicities. Each group showed a high incidence of low serum B12 concentrations, with a 22.3% incidence among Ashkenazi Jews and 40% among patients with Gaucher disease. These findings raise questions on the individual and community levels of serum B12. We recommend evaluation of B12 levels among geographically contingent peoples.

Lung involvement and enzyme replacement therapy in Gaucher's disease

Symptomatic lung involvement in Gaucher's disease is relatively rare, being restricted to patients with other severe manifestations. We describe our experience in eight of 411 patients in our referral clinic, who presented with prominent pulmonary signs or symptoms. There were four adults and four children; all have been successfully treated with enzyme replacement therapy. Routine means of monitoring pulmonary status including clinical assessment, chest X-ray, pulmonary function tests, and high-resolution CT (HRCT) were used. Enzyme treatment resulted in decreased hepatosplenomegaly, improved haematological parameters, and increased well-being; There was decreased clubbing and decreased dyspnoea in some of the patients, although on radiology, lung pathology had not normalized. All four children showed improved respiratory compliance, with significant improvement of the radiological findings in one and unchanged disease in the others. Two adults showed improvement in oxygen saturation but worsening of pulmonary hypertension. On chest X-ray, both had increased interstitial markings; one had gradual progression of pulmonary artery accentuation and fine interstitial stable pattern on HRCT. The other two adults had no change in lung function or on chest X-ray, but on HRCT there was apparent improvement in one patient. There is great heterogeneity in presentation and response to enzyme therapy in patients with Gaucher's disease and symptomatic lung involvement. Clinically, some benefited significantly from enzyme therapy, but in contrast to the dramatic reduction in organomegaly, there was no normalization in pulmonary function or lung architecture.

Effect of ozone on neutrophil function in vitro

The application of ozone is widely practised as a form of alternative medicine, particularly in Germany and Eastern Europe. Ozone major autohemotherapy (the return of a small amount of a patient's blood to the circulation after ex vivo exposure to ozone) has been reported to have a therapeutic effect in various pathological conditions, including ischemic, infectious, autoimmune and neoplastic disorders. Ozone has an effect on the expression of cytokines, adhesion molecules and acute phase reactants, which are responsible in part for the respiratory inflammatory response observed after exposure to this gas. The purpose of the present study was to investigate the effect of ozone administration ex vivo, at a concentration commonly used in major autohemotherapy, on peripheral blood neutrophil function in vitro. Blood drawn from healthy volunteers was studied for neutrophil adhesion, chemotaxis and O-2 production before and after exposure to 30 microg/ml ozone. There was no significant difference in adhesion and chemotaxis of neutrophils exposed to ozone versus unexposed cells. O-2 production was minimally decreased (20.3 +/- 5.0 vs. 22.1 +/- 5.5 nmol/106 cells/10 min, respectively; P=0.01), a reduction of no clinical significance. This study confirms that major autohemotherapy with ozone is safe as far as neutrophil function is concerned. Combined with previous data, it seems that well-designed clinical trials to assess the efficacy of major autohemotherapy would pose no danger to blood cell populations, and should be encouraged.

High prevalence of complement C7 deficiency among healthy blood donors of Moroccan Jewish ancestry

The incidence of the specific component deficiencies in various ethnic groups is not known, although there appears to be an ethnic predilection for C6 and C8alpha-gamma deficiencies in blacks, whereas C7 and C8beta deficiencies are predominantly noted in Caucasians. Infectious diseases, particularly recurrent meningococcal infections, are observed more commonly with late component deficiencies. In the current study, we have simplified the PCR technique by using site-directed mutagenesis and designer primers in a cohort of Israeli Moroccan Jewish blood donors to ascertain allele frequency in this ethnic group, which, based on earlier studies, was considered to be at risk for C7 deficiency. The total mutant allele frequency in this ethnic cohort was 1.1% of a total of 365 healthy Israeli Moroccan Jews, including one homozygote. The identification of mutant alleles was efficient and inexpensive, and hence a large cohort was studied. The finding of complement deficiency identifies individuals at risk for Neisserial infections, which are known to be potentially life-threatening. Conversely, when a patient of Moroccan ancestry is diagnosed with a Neisserial infection, it is important to determine the complement status.

Inhibition of substrate synthesis as a strategy for glycolipid lysosomal storage disease therapy

The glycosphingolipid (GSL) lysosomal storage diseases are caused by mutations in the genes encoding the glycohydrolases that catabolize GSLs within lysosomes. In these diseases the substrate for the defective enzyme accumulates in the lysosome and the stored GSL leads to cellular dysfunction and disease. The diseases frequently have a progressive neurodegenerative course. The therapeutic options for treating these diseases are relatively limited, and for the majority there are no effective therapies. The problem is further compounded by difficulties in delivering therapeutic agents to the brain. Most research effort to date has focused on strategies for augmenting enzyme levels to compensate for the underlying defect. These include bone marrow transplantation (BMT), enzyme replacement and gene therapy. An alternative strategy that we have been exploring is substrate deprivation. This approach aims to balance the rate of GSL synthesis with the impaired rate of GSL breakdown. The imino sugar N-butyldeoxynojirimycin (NB-DNJ) inhibits the first step in GSL biosynthesis and has been used to evaluate this approach. Studies in an asymptomatic mouse model of Tay-Sachs disease have shown that substrate deprivation prevents GSL storage in the CNS. In a severe neurodegenerative mouse model of Sandhoff disease, substrate deprivation delayed the onset of symptoms and disease progression and significantly increased life expectancy. Combining NB-DNJ and BMT was found to be synergistic in the Sandhoff mouse model. A clinical trial in type I Gaucher disease has been undertaken and has shown beneficial effects. Efficacy was demonstrated on the basis of significant decreases in liver and spleen volumes, gradual but significant improvement in haematological parameters and disease activity markers, together with diminished GSL biosynthesis and storage as determined by independent biochemical assays. Further trials in type I Gaucher disease are in progress; studies are planned in patients with GSL storage in the CNS.

Viral infections and phenotypic heterogeneity in Gaucher disease

Gaucher disease, the most common lysosomal storage disorder, is remarkable for its tremendous phenotypic heterogeneity even among patients with the same genotype. Beyond mutations at the 1q21 locus, there may be other genetic and environmental factors that impact on the natural course of Gaucher disease and indeed may trigger symptoms and signs. Among candidate events are viral infections such as the Epstein-Barr virus (EBV) or cytomegalovirus (CMV). The purpose of this study was to ascertain if indeed prior infection with EBV or CMV in patients homozygous for the most common mutation, N370S (1226G), is predictive of a more severe phenotype. Evidence for an EBV virus was IgG and IgM antibodies to early antigen and IgG anti-EBNA. For CMV infection, IgG and IgM antibodies were sought. This study failed to demonstrate any correlation between prior EBV or CMV infection and clinical course of Gaucher disease in patients homozygous for the N370S (1226G) mutation. The only positive finding was a higher level of anti-EBNA antibodies among patients with moderate/severe disease. In conclusion, other than a small subset of patients who showed a pattern comparable to immunosuppression, there was no association between severity of Gaucher disease and prior EBV or CMV infection.

Outcome of total hip arthroplasty in patients with Gaucher disease

This retrospective survey includes 29 total hip arthroplasties (THAs) in 23 patients with Gaucher disease, with heterogeneous techniques, with various prostheses, and performed by 9 different surgical teams. THA was discouraged in patients with Gaucher disease because of a tendency toward infection, poor bone matrix because of Gaucher cell infiltration, and deterioration of matrix with disease progression. Subjective assessment of pain and function, objective examination of outcome, and radiologic signs of loosening after THA were evaluated. In primary THAs, there was enhancement of quality of life, allowing restoration of full participation in normal activities; function was improved; radiologic evidence of loosening was low; and there were no infections. In revisions, the results were not as good. THA is recommended in this population using criteria comparable to those in other patients, with equally good results.

Incidence of thrombophilia in patients with Gaucher disease

An inherited risk for thrombosis, including mutant thermolabile variant of methylenetetrahydrofolate reductase (MTHFR), factor V Leiden, or prothrombin may be the co-factor(s) for avascular necrosis (AVN) in patients with sickle cell disease. Similarly, heterozygosity for factor V Leiden is sufficient to explain the increased blood viscosity observed in children with Legg-Calve-Perthes disease who develop AVN. Because there are no laboratory tests or clinical markers that are helpful in predicting which patients with Gaucher disease may develop AVN, the current study was undertaken to ascertain if there exists an inherited predilection to hypercoagulability in patients with Gaucher disease and AVN. Analysis was performed on genomic DNA extracted from 56 adult patients with type I Gaucher disease. In this cohort of Ashkenazi Jewish patients, the frequency of mutations in the MTHFR, prothrombin, and factor V Leiden genes was found to be low, as was the presence of anticardiolipin antibodies; and none was correlated with increased incidence of AVN. Splenectomy, that may be a predisposing factor to AVN in patients with Gaucher disease, was factored out. Hence the presence of any of the above thrombophilic factors, and which by extension may be risk factors for AVN in other diseases, are not more common in patients with Gaucher disease who develop AVN. Studies in larger cohorts and possibly inclusion of additional factors may be needed to ascertain whether a correlation exists.

[Relevance and feasibility of a surveillance system of the effects of atmospheric pollution]

New regulations on the quality of air together with the epidemiological results obtained in the last 10 years on the short-term effects of air pollution on health have led the InVS to set up a program of epidemiological surveillance in 9 French cities. The first phase of this program was dedicated to the study of feasibility of such a surveillance system. Metrological and health data collection was conducted at both local and national levels in order to obtain significant data in close collaboration with experts of each field. The analysis of the relationship between temporal variations of daily series of the two types of indicators have allowed to obtain dose-response relationships between air pollution and mortality. The organisational and technical feasibility of such a surveillance system was confirmed in the first phase of the program.

Withdrawal of enzyme replacement therapy in Gaucher's disease

Although enzyme replacement therapy is safe and effective in ameliorating the signs and symptoms of Gaucher's disease, some patients have withdrawn from treatment. The purpose of this study was to evaluate the response to withdrawal and to discuss the implications for patients currently on unaltered therapy regimens since the advent of treatment. Fifteen patients, who had been treated with enzyme replacement for 5-56 months and then withdrew for 8-47 months, were assessed for changes in haematological parameters and in liver and spleen index volume. Despite non-uniformity of duration of on and off periods, degree of organomegaly, anaemia and thrombocytopenia, most patients did not revert to respective baseline values in most parameters after withdrawal. None of the patients suffered exacerbation of bone involvement or had new or aggravated pulmonary hypertension. Adult patients with stable Gaucher's disease may be withdrawn from therapy for circumscribed periods without forfeiting most gains accrued during enzyme therapy. Therefore, stopping and restarting may be considered in some patients. Alternatively, maintenance at reduced dosage and/or frequency may be appropriate in some adult patients who are stable or non-responsive after the first years of enzyme therapy. This caveat does not apply to children.

Novel oral treatment of Gaucher's disease with N-butyldeoxynojirimycin (OGT 918) to decrease substrate biosynthesis

BACKGROUND

Current treatment for Gaucher's disease involves administration of intravenous glucocerebrosidase to degrade glucocerebroside stored in lysosomes. Lowering the rate of biosynthesis of glucocerebroside should decrease accumulation of this substrate. We investigated the safety and efficacy of OGT 918 (N-butyldeoxynojirimycin), an inhibitor of glucosyltransferase, as a novel oral treatment for non-neuronopathic Gaucher's disease.

METHODS

We recruited, into a 1-year open-label study, 28 adults (seven with previous splenectomies) from four national Gaucher's referral clinics, who were unable or unwilling to receive enzyme treatment. We measured liver and spleen volume by computed tomography or magnetic resonance imaging at baseline and at months 6 and 12, and biochemical and haematological variables monthly, including chitotriosidase activity (a sensitive marker of Gaucher's disease activity). Patients were started on 100 mg oral OGT 918 three times daily.

FINDINGS

Baseline liver volumes were 1.1-2.7 times normal and spleen volumes 5.1-24.8 times normal. At 12 months, mean liver and spleen volumes were significantly lowered by 12% (95% CI 7.8-16.4) and 19% (14.3-23.7), respectively (each p<0.001). Haematological variables improved slightly. Mean organ volume and blood counts improved continually between 6 months and 12 months of treatment. Mean chitotriosidase concentrations fell by 16.4% over 12 months (p<.0001). Six patients withdrew because of gastrointestinal complaints (two), personal reasons (two), or severe pre-existing disease (two). The most frequent adverse effect was diarrhoea, which occurred in 79% of patients shortly after the start of treatment.

INTERPRETATION

Decrease of substrate formation by OGT 918 improves key clinical features of non-neuronopathic Gaucher's disease. The strategy justifies further trials in this and other glycosphingolipid storage disorders.

Is there a correlation between degree of splenomegaly, symptoms and hypersplenism? A study of 218 patients with Gaucher disease

Despite the prevalence of splenomegaly as a sign in many disorders, there have been no studies that correlate the degree of organomegaly with the symptoms generally ascribed to splenic enlargement. The degree of splenomegaly was compared with five overt symptoms of mechanical displacement, i.e. chronic abdominal pain, abdominal discomfort, early satiety, pain while lying on the side, or attacks of acute (colicky) left upper quadrant pains. We have also employed splenomegaly as seen in Gaucher disease as a paradigm to determine whether there is a correlation between the degree of splenomegaly and the parameters of hypersplenism. Although there was a statistically significant correlation between degree of splenomegaly and blood counts, this proved to be clinically negligible. Surprisingly, there was also no correlation between degree of splenomegaly and any of symptoms investigated.

Asymptomatic Gaucher disease implications for large-scale screening

Gaucher disease, the most prevalent genetic disorder among Ashkenazi Jews, is characterized by significant phenotypic heterogeneity. Because seven mutations account for more than 96% of the disease alleles in this population, large-scale screening is feasible, and genotyping is commercially available. To date, only 400 Gaucher patients have been diagnosed in Israel, although 2,500 patients are predicted by gene frequency; hence, there is the probability that those uncovered by population screening will prove to be very mild or asymptomatic since these patients have generally escaped medical attention until now. We studied objective and subjective aspects in 68 asymptomatic/very mild patients, followed for a mean of 2.6 years, to assess the implications of identifying many more such patients if large-scale screening were to be implemented. We found there were no medically significant changes in disease severity during follow-up. The patients' subjective reports of their general health status were similar to those of normal subjects, and there were no significant changes in quality of life during follow-up. Our findings suggest that asymptomatic/mild Gaucher patients do not require frequent monitoring; there is no justification for "prophylactic" enzyme therapy in this group, and, hence, no rationale for large-scale screening in the Ashkenazi population. Furthermore, one needs to be concerned with the adverse effects of labeling large numbers of asymptomatic individuals as affected because of the potential for stigmatization and discrimination.

Platelet function abnormalities in Gaucher disease patients

Bleeding manifestations are common in Gaucher disease patients. Although usually attributed to thrombocytopenia, some patients with relatively high platelet counts and normal coagulation tests have hemorrhagic phenomena. To investigate whether perturbed platelet function could explain these bleeding manifestations we performed platelet aggregation tests on 32 type I adult Gaucher patients who were not severely thrombocytopenic (platelet counts >50 x 10(9)/L). Seven patients (22%) had abnormal platelet aggregation. In five, platelet aggregation was markedly reduced in response to collagen and ADP and virtually absent in response to epinephrine, whereas two patients had isolated severely impaired epinephrine-induced aggregation. In one patient platelet aggregation markedly improved following one year of enzyme replacement therapy. Incubating normal platelets with high concentrations of glucocerebroside did not impair their ability to aggregate, suggesting that plasma glucocerebroside does not directly interfere with platelet function. Platelet dysfunction is a hitherto unrecognised, relatively common cause of excessive bleeding in Gaucher patients.

Gaucher's disease with valve calcification: possible role of Gaucher cells, bone matrix proteins and integrins

Gaucher's disease, an autosomal recessive storage disease, leads to deposition of glucocerebrosides in various organs, especially those of the reticuloendothelial system. The heart is not thought to be frequently involved and studies of patients with cardiac involvement have concentrated on myocardial involvement. Despite careful prior investigation Gaucher cells have never been detected in the valves of these patients. Pathological findings of a patient with Gaucher's disease, type IIIc, with prominent cardiac valvular involvement are reported and, for the first time, the presence of Gaucher cells in the valve tissue is documented. There is evidence that the pathogenesis of the valvular injury may be by way of a cell-mediated mechanism involving bone matrix proteins and integrins.

Ethical considerations for enzyme replacement therapy in neuronopathic Gaucher disease

Enzyme replacement therapy for Gaucher diseases, the most prevalent lysosmal storage disease, was originally approved by the FDA for type I patients and has proven to be both safe and effective in reducing hepatosplenomegaly and improving the hematological parameters. However, the use of enzyme treatment in both neuronopathic forms has heretofore been on an investigational or trial basis, with reports of progression of neurological deterioration even at very high doses. To date, there are no guidelines for clinicians with regard to enzyme replacement therapy in the neuronopathic forms of metabolic diseases. Herein. we discuss strategies derived from the literature vis-à-vis treatment of very premature babies and from the Jewish Halachic point of view. In conclusion. we describe recommendations for the ethical treatment and/or withdrawal of treatment, as well as practical guidelines for dosage regimens, in children with neuronopathic Gaucher disease.

Low-dose low-frequency imiglucerase as a starting regimen of enzyme replacement therapy for patients with type I Gaucher disease

The issue of the interplay of optimal dosage and frequency regimens for enzyme replacement therapy in type I Gaucher disease has been a source of controversy during the 7 years since the introduction of the placenta-derived enzymatic preparation in 1991. We present the results of treatment with the human recombinant form of the enzyme in 28 type I Gaucher patients, who have been treated for 6 to 24 months. As long as cost is an important factor in the management of patients with Gaucher disease, low-dose low-frequency imiglucerase promises satisfactory clinical improvement without compromising quality of life.

Echocardiographic assessment of pulmonary hypertension in Gaucher's disease

BACKGROUND

Enzyme therapy has been shown to decrease the signs and symptoms of Gaucher's disease. A few patients, however, develop pulmonary hypertension on such treatment. We investigated the frequency of pulmonary hypertension in Gaucher's disease.

METHODS

We studied 134 adults with type 1 Gaucher's disease, including 73 patients on enzyme replacement, with echocardiography. We measured tricuspid incompetence (TI) with continuous-wave doppler. Pulmonary hypertension was indicated by a TI gradient of more than 30 mm Hg.

FINDINGS

Nine (7%) patients had pulmonary hypertension: all were treated and six had undergone splenectomy. Chest radiographs confirmed the presence of pulmonary hypertension in these patients as well as in most patients with TI gradients of 25-29 mm Hg.

INTERPRETATION

The confounding effects of disease severity and splenectomy in many treated patients precluded definitive conclusion of cause and effect. Nonetheless, we found an unexpectedly high rate of pulmonary hypertension and recommended routine echocardiographic monitoring of all treated and untreated patients with type 1 Gaucher's disease. We also suggest consideration of treatment withdrawal if the TI gradient progresses to more than 30 mm Hg.

The nature and extent of jaw involvement in Gaucher disease: observations in a series of 28 patients

A wide variety of osteoarticular pathoses plague the clinical course of many patients with Gaucher disease. Osseous lesions involving the jaws have been described, usually as isolated case reports. The purpose of this study was to ascertain the nature and extent of mandibulo-maxillofacial pathosis in 28 patients with documented Gaucher disease by means of panoramic radiography. Twenty-five of the 28 patients displayed radiographic evidence of jaw involvement. The most prevalent finding was gross widening of marrow spaces; frank radiolucencies, endosteal scalloping, cortical thinning, root resorption, and inferior displacement of the mandibular canal or effacement of its cortices were also seen. A previously unreported finding was delayed eruption of permanent teeth, which was seen in more than one half of the patients who were under 20 years of age. Osseous changes throughout the jaws may be more common than previously suspected and may alert the dentist to the presence of the disease.

Use of enzyme replacement therapy for Gaucher disease during pregnancy

OBJECTIVE

To date there has been little published experience with enzyme replacement therapy in pregnant women with symptomatic type I Gaucher disease.

STUDY DESIGN

We describe six patients, including three with repeated early pregnancy loss, five of whom successfully carried pregnancies to term; the last pregnancy was terminated because of pulmonary hypertension.

RESULTS

All pregnancies were uneventful and five resulted in healthy newborns.

CONCLUSION

We concluded that in patients with Gaucher disease of childbearing age,for whom obstetric complications are an important symptom of the disease, pregnancy is not contraindicated (unless there is evidence or suspicion of pulmonary hypertension) and treatment should not be interrupted because the clinical improvement engendered by enzyme replacement therapy is conducive to fewer complications during pregnancy and delivery and post partum.

Skeletal involvement in Gaucher's disease

Perhaps the most variable of all the symptoms attributed to Gaucher's disease is that of bone involvement, both in the Type 1 and Type 3 forms of the disease. Expression of skeletal involvement in Gaucher patients ranges from asymptomatic disease, with or without radiological signs, to symptomatic disease, which can be severe and engender considerable pain and disability. Herein we discuss the imaging techniques currently available to document the presence and progression of bone involvement as well as the various forms of medical and surgical management that are employed to help the Gaucher patient cope with skeletal disease.