HUMAN MATERNAL UNIPARENTAL DISOMY FOR CHROMOSOME-16 AND FETAL DEVELOPMENT

Two severely growth-retarded fetuses found to have maternal uniparenta l disomy (UPD) for chromosome 16 and trisomy 16 placental mosaicism bo th had an unfavourable outcome. Antenatally, the first case was compli cated by an unexplained raised maternal serum alpha-fetoprotein concen tration, preterm premature rupture of the membranes, and growth retard ation detectable at 21 weeks' gestation, whilst the other had an unexp lained raised maternal serum human chorionic gonadotrophin level, a tw o-vessel cord on ultrasound, and cessation of growth at 25 weeks. At p ost-mortem, both babies had an imperforate anus. Fetal maternal UPD ma y explain the poor outcome that occurs in some cases of confined place ntal mosaicism for chromosome 16 and is also associated with specific fetal abnormalities.