Changes of serum hexosaminidase for the presumptive diagnosis of type I Gaucher disease in Tay-Sachs carrier screening.

Although reduced acid beta-glucosidase activity appears to be the primary enzyme defect in type I Gaucher disease, patients with this disorder also have marked elevation of serum acid phosphatase and beta-hexosaminidase activities but with a normal level of lactic dehydrogenase activity. Moreover, there is a characteristic alteration in the hexosaminidase isozyme distribution with a striking increase in hexosaminidase B. Since these changes appear to be consistent and unlike those associated with other disorders or the hormonally induced alterations associated with pregnancy, routine serum testing for the Tay-Sachs carrier state may offer a useful approach for the presumptive diagnosis and screening for Gaucher disease. Unlike the changes in affected homozygotes, there are no characteristic alterations of acid phosphatase or hexosaminidase in heterozygotes for Gaucher disease.