Frequency of carriers of chronic (type I) Gaucher disease in Ashkenazi Jews.

In this study we estimate the frequency of carriers of chronic (type I) Gaucher disease among Ashkenazi Jews by examining the glucocerebrosidase activity in leukocytes in a population of 635 blood donors (441 Ashkenazi) and 57 obligatory heterozygotes. Estimation using the defect in the enzyme glucocerebrosidase (beta-glucosidase) in leukocytes is complicated by the existence of considerable overlap between enzyme activity in normals and in heterozygotes. The assay was carried out with a natural substrate labeled with 14C. Discriminant analysis was used to establish an optimal cutoff point between the obligatory heterozygotes and normal (non-Ashkenazi) subjects for the purpose of estimating frequency of carriers. Applied to the Ashkenazi group, the cutoff point identified 3.17% as heterozygotes. Corrected for errors in classification, the carrier rate was estimated as 4.67%. This figure is in good agreement with a carrier rate of 4% estimated from the number of known cases of clinical Gaucher disease ascertained in Israel.