 The encoded protein is found in the endoplasmic reticulum, where it is present as a homodimer.A congenital deficiency in the enzyme is associated with X-linked ichthyosis, a scaly-skin disease affecting roughly 1 in every 2,000 to 6,000 males.The excessive skin scaling or hyperkeratosis is caused by a lack of breakdown and thus accumulation of cholesterol sulfate, a steroid that stabilizes cell membranes and adds cohesion, in the outer layers of the skin.