Polymorphisms in glucosylceramide (glucocerebroside) synthase and the Gaucher disease phenotype

Gaucher disease results from the accumulation of glucosylceramide (glucocerebroside) in tissues of affected persons. Patients sharing the same genotype present with widely varying degrees of lipid storage and of clinical manifestations.

To determine whether variation in the glucosylceramide synthase (UDPGlucose ceramide glucosyltransferase) gene, which encodes the enzyme that regulates the synthesis of glucocerebroside, could account for the variability and clinical manifestations.

Patients homozygous for the 1226G (N370S) mutation, the most common in the Ashkenazi Jewish population, were investigated. The exons and flanking sequences of the gene were sequenced using DNA derived from five very mild Gaucher disease patients and four patients with relatively severe Gaucher disease.

One polymorphism was found in the coding region, but this did not change any amino acids. Seven other polymorphisms were found in introns and in the 5' untranslated region. Some of these were single nucleotide polymorphisms; others were insertions. The mutations appear to be in linkage equilibrium and none were found with a significantly higher frequency in either severe or mildly affected individuals.

Mutations in the glucosylceramide synthase gene do not appear to account for the variability in expression of the common Jewish Gaucher disease mutation.