IDENTIFICATION AND EXPRESSION OF ACID BETA-GLUCOSIDASE MUTATIONS CAUSING SEVERE TYPE-1 AND NEUROLOGIC TYPE-2 GAUCHER-DISEASE IN NON-JEWISH PATIENTS

Gaucher disease, the most prevalent lysosomal storage disease, occurs in three subtypes, all resulting from mutations in the acid beta-gluco sidase gene, Molecular studies in five severely affected type 1 and tw o type 2 Gaucher disease patients of non-Jewish descent identified six new mutations: K74X, W179X, G195E, S271N, V352L, and a two-base delet ion in exon 10 (1450del2), Two additional mutations identified in thes e patients (R48W and G202R) have been reported previously, but were no t expressed or characterized, Heterologous expression in Sf9 cells usi ng the baculovirus system revealed that the missense mutations, R48W a nd V352L, had 14 and 7%, respectively, of the specific activity based on cross-reacting immunologic material expressed by the normal allele, In contrast, the G195E, G202R, and S271N mutant alleles were more sev erely compromised with only 1-2% of the normal expressed specific acti vity based on cross-reacting immunologic material, Structural distorti on at the active site was probed by comparing the interaction of the m utant enzymes with active site-directed inhibitors (castanospermine, c onduritol B epoxide and deoxynojirimycin), R48W, G202R, and S271N were normally inhibited, whereas the V352L and G195E mutant enzymes had si gnificantly decreased binding affinity, These mutations further expand the genetic heterogeneity in the lesions causing Gaucher disease type s 1 and 2, and further delineate genotype/phenotype correlations and f unctional domains within the acid beta-glucosidase gene.