ANTENATAL MOLECULAR DIAGNOSIS OF X-LINKED ICHTHYOSIS BY MATERNAL SERUM SCREENING FOR DOWNS-SYNDROME

A case of X-linked ichthyosis diagnosed antenatally by molecular analy sis of fetal DNA is described. The diagnosis was made at 16 weeks gest ation, following the finding of a maternal serum unconjugated estriol level lower than 0.1 MoM when performing a triple test. Fetal DNA was obtained from cultured amniocytes; two specific regions were amplified by polymerase chain reaction at 5' and 3' ends of the steroid sulfata se (STS) gene on Xp22.3 region. Analysis showed complete deletion of t he STS gene on the distal tip of the X-chromosome short arm.