Gaucher disease, a condition transmitted by autosomal recessive inheritance, results from a genetic defect in beta-glucosidase, an enzyme which degrades sphingolipids. Deficiency in beta-glucosidase leads to accumulation of its substrate, glycosylceramide, in macrophages and, in the more severe cases, in neurons. Clinically, splenomegaly, hepatomegaly, bone destruction, cytopenia, and in some cases, central neurological lesions develop. Three phenotypes have been described according to the absence (type 1) or presence of neurological involvement (type 2: severe, type 3: intermediate severity). The disease occurs in patients of all ethnic origins but type 1 is particularly well known in Ashkenese Jews and type 3 is found in the Swedish province of Norrbottnie. About forty mutations of the beta-glucosidase gene have been identified. Four account for 80% of the known mutations (1226G, 1448C, 84GG, IVS2+1). Residual enzyme activity of mutant beta-glucosidase explains some of the phenotypic variations. The phenotype resulting from the 1226G mutation has sufficient enzyme activity for degradation of gangliosides in the brain, explaining the absence of neurological involvement in patients with this allele. Treatment is based on enzyme supplemention: blood parameters return to normal and the volume of the spleen and liver are greatly reduced after 6 months. In infants with very severe disease, bone marrow graft may be used.