Normal activity of C₂₇-steroid 26-hydroxylase in cultured sitosterolaemia fibroblasts

Abstract

The primary defect in sitosterolaemia is unknown. In some patients excretion of bile alcohols is increased, and it has been suggested that the defect is located to some step in the biosynthesis of bile acids. The activity of C₂₇-steroid 26-hydroxylase was measured in cultured skin fibroblasts from a sitosterolaemic patient. The same assay was used as before in demonstrating deficiency of this enzyme activity in cerebrotendinous xanthomatosis (CTX), a disease in which high excretion of bile alcohols is typical. The substrate, 5β-cholestane-3α, 7α, 12α-triol, was 26-hydroxylated to the same extent in the patient cells as in those of healthy controls. Thus, the sitosterolaemia cells have a normal activity of this enzyme.

Key words:

• bile acid biosynthesis
• bile alcohols
• phytosterolaemia