An improved fluorometric leukocyte beta-glucosidase assay for Gaucher's disease.

Three fluorometric leukocyte beta -glucosidase assays were compared for their ability to diagnose Gaucher's disease and identify carriers of the disorder: the acid beta-glucosidase assay of Beutler and Kuhl [2], a pH 5.5-sodium taurocholate-dependent assay and a new procedure which employs conduritol B epoxide, an active-site specific inhibitor of glucocerebrosidase. All three assays unambiguously identified patients with Gaucher's disease. With regard to identifying carriers the bile salt dependent assay of Peters et al. and the conduritol B epoxide-dependent procedure gave the greatest discrimination between the mean beta-glucosidase values for the control and heterozygote samples when evaluated using Student's t test. The most reliable assay for the identification of the carrier state was the conduritol B epoxide-dependent procedure which can be expected to provide the fewest false negative results when classifying heterozygotes (5%). However, the fact that none of these methods will completely separate control and heterozygote samples indicates that their use in screening programs will result in a significant number of incorrect assignments.