Enzymatic basis of typical X-linked icthyosis.

Steroid sulphatase activity was determined in cultured fibroblasts from 25 individuals with X-linked ichthyosis from four countries. All those with X-linked disease had markedly reduced enzyme levels compared with controls and patients with other types of ichthyosis. X-linked ichthyosis seems to be the result of a common mutation affecting the expression of steroid-sulphatase activity.