Diagnosing neuronopathic Gaucher disease: New considerations and challenges in assigning Gaucher phenotypes

Recent studies indicate an increased frequency of mutations in the gene encoding glucocerebrosidase (GBA), a deficiency of which causes Gaucher's disease, among patients with Parkinson's disease. We aimed to ascertain the frequency of GBA mutations in an ethnically diverse group of patients with Parkinson's disease. Sixteen centers participated in our international, collaborative study: five from the Americas, six from Europe, two from Israel, and three from Asia. Each center genotyped a standard DNA panel to permit comparison of the genotyping results across centers. Genotypes and phenotypic data from a total of 5691 patients with Parkinson's disease (780 Ashkenazi Jews) and 4898 controls (387 Ashkenazi Jews) were analyzed, with multivariate logistic-regression models and the Mantel-Haenszel procedure used to estimate odds ratios across centers. All 16 centers could detect two GBA mutations, L444P and N370S. Among Ashkenazi Jewish subjects, either mutation was found in 15% of patients and 3% of controls, and among non-Ashkenazi Jewish subjects, either mutation was found in 3% of patients and less than 1% of controls. GBA was fully sequenced for 1883 non-Ashkenazi Jewish patients, and mutations were identified in 7%, showing that limited mutation screening can miss half the mutant alleles. The odds ratio for any GBA mutation in patients versus controls was 5.43 across centers. As compared with patients who did not carry a GBA mutation, those with a GBA mutation presented earlier with the disease, were more likely to have affected relatives, and were more likely to have atypical clinical manifestations. Data collected from 16 centers demonstrate that there is a strong association between GBA mutations and Parkinson's disease. 2009 Massachusetts Medical Society

Gaucher's disease, the most prevalent of the sphingolipid storage disorders, is caused by a deficiency of the enzyme glucocerebrosidase (glucosylceramidase). Enzyme replacement was proposed as a therapeutic strategy for this disorder in 1966. To assess the clinical effectiveness of this approach, we infused macrophage-targeted human placental glucocerebrosidase (60 IU per kilogram of body weight every 2 weeks for 9 to 12 months) into 12 patients with type 1 Gaucher's disease who had intact spleens. The frequency of infusions was increased to once a week in two patients (children) during part of the trial because they had clinically aggressive disease. The hemoglobin concentration increased in all 12 patients, and the platelet count in 7. Serum acid phosphatase activity decreased in 10 patients during the trial, and the plasma glucocerebroside level in 9. Splenic volume decreased in all patients after six months of treatment, and hepatic volume in five. Early signs of skeletal improvements were seen in three patients. The enzyme infusions were well tolerated, and no antibody to the exogenous enzyme developed. Intravenous administration of macrophage-targeted glucocerebrosidase produces objective clinical improvement in patients with type 1 Gaucher's disease. The hematologic and visceral responses to enzyme replacement develop more rapidly than the skeletal response.

Gaucher disease (GD; glucosylceramidosis) is caused by a deficient activity of the enzyme glucocerebrosidase (GC). Clinical manifestations are highly variable and cannot be predicted accurately on the basis of the properties of mutant GC. Analysis of secondary abnormalities, such as elevated plasma levels of some hydrolases, may help to increase insight into the complicated pathophysiology of the disease and could also provide useful disease markers. The recent availability of enzyme supplementation therapy for GD increases the need for markers as early predictors of the efficacy of treatment. We report the finding of a very marked increase in chitotrisidase activity in plasma of 30 of 32 symptomatic type 1 GD patients studied: the median activity being > 600 times the median value in plasma of healthy volunteers. In three GC-deficient individuals without clinical symptoms, only slight increases were noted. Chitotriosidase activity was absent in plasma of three control subjects and two patients. During enzyme supplementation therapy, chitotriosidase activity declined dramatically. We conclude that plasma chitotriosidase levels can serve as a new diagnostic hallmark of GD and should prove to be useful in assessing whether clinical manifestations of GD are present and for monitoring the efficacy of therapeutic intervention.