Prenatal diagnosis of X-linked ichthyosis.

Prenatal diagnosis of X-linked ichthyosis in a case of steroid sulfatase deficiency was made at 16 weeks by the demonstration of (1) high levels of dehydroepiandrosterone sulfate in amniotic fluid; (2) gross deficiency of steroid sulfatase activity in cultured amniotic fluid cells; (3) very low estriol concentrations in maternal blood and urine; (4) increased maternal plasma dehydroepiandrosterone sulfate; and (5) a characteristic maternal urinary steroid profile with greatly increased levels of 16 alpha-hydroxydehydroepiandrosterone. The latter method is particularly useful since it requires no invasive procedures for the patient and is very specific.