X-linked ichthyosis is a genetic skin disorder that affects males. It is an inborn error of metabolism characterized by a deficiency of the enzyme steroid sulfatase. Under normal conditions, this enzyme breaks down (metabolizes) cholesterol sulfate, a member of the chemical family of steroids. Cholesterol sulfate plays a role in maintaining the integrity of the skin. If steroid metabolism is interrupted and cholesterol sulfate accumulates in the skin cells, the skin cells stick together more strongly than usual.
Reference: Rare Diseases (NORD)