PRENATAL DETECTION OF X-LINKED ICHTHYOSIS BY MATERNAL SERUM SCREENINGFOR DOWN-SYNDROME

Maternal serum unconjugated oestriol (uE3) was measured in 15 375 preg nancies during 2 years of second-trimester risk assessment for Down sy ndrome using biochemical markers. Very low levels of uE3 (<0.1 MOM) we re detected in 22 serum samples (0.14 per cent). Very low uE3 was asso ciated with an adverse outcome in 13 pregnancies including fetal death and miscarriage (N = 11), anencephaly (N = 1), and Meckel-Gruber synd rome (N = 1). Dry scales on the skin appeared in the first year of lif e in four boys. From dermatological diagnosis, prenatal uE3 levels, an d pedigree analysis, it is concluded that at least 5 in approximately 7500 male births in the study population are affected by steroid sulph atase deficiency, which is the biochemical defect in X-linked ichthyos is. Very low uE3 levels in the second trimester are indicative of this disease in pregnancies with normal ultrasound findings.