Discordant Expression of Fetal Hydantoin Syndrome in Heteropaternal Dizygotic Twins

Abstract

PRENATAL exposure to hydantoin analogues, including phenytoin, may result in the fetal hydantoin syndrome — a symptom complex characterized by poor growth and development with specific craniofacial and skeletal abnormalities.^{1 2 3 4} The full syndrome is seen in about 11 per cent of exposed infants, and an additional 31 per cent have partial expression of the teratogenic effects.¹ The resulting dysmorphism is most striking at birth and generally becomes less pronounced with age, although the associated mental deficiency is permanent.² Variability in the clinical manifestations of fetal hydantoin syndrome has been described in fraternal twins^{3 , 4} and triplets⁵ who were presumably exposed to . . .