Measuring Scale Steroid Sulfatase and ß-Lipoprotein Mobility in Ichthyosis

To the Editor.— X-linked ichthyosis, as pointed out by Epstein et al in a recent editorial in the DecemberArchives(1981;117:761-763) is a genetic disorder with a specific biochemical defect—an absence of steroid sulfatase activity associated with an accumulation of cholesterol sulfate in the skin. A simple, noninvasive assay was reported by Baden et al,1involving measurement of steroid sulfatase in scale or callus samples scraped from the feet. Epstein and Leventhal2described a technique (available in most clinical laboratories) to demonstrate increased electrophoretic mobility of low-density lipoproteins due to a greater cholesterol-sulfate content. Our extensive experience with patients with ichthyosis has made us realize that the value of these tests has not been fully appreciated by the practicing dermatologist. Report of a Case.— We recently saw a 56-year-old man with apparent sex-linked ichthyosis, whose condition was diagnosed by the referring physician on the basis of his clinical