Fetal hydantoin syndrome

Fetal hydantoin syndrome (FHS), also known as fetal dilantin syndrome or phenytoin embryopathy, is a pattern of birth defects that occurs in some children born to mothers who took the anticonvulsant medication phenytoin (Dilantin) during pregnancy. It is not an inherited genetic disorder but rather a teratogenic condition caused by prenatal exposure to phenytoin, which interferes with normal fetal development. The syndrome affects multiple body systems, including the craniofacial structures, limbs, cardiovascular system, and central nervous system. Key clinical features include a distinctive facial appearance characterized by a broad, flat nasal bridge, short nose, wide mouth, cleft lip and/or palate, hypertelorism (widely spaced eyes), and epicanthal folds. Limb abnormalities are common and include hypoplasia (underdevelopment) of the distal phalanges and nails, particularly of the fingers and toes. Children may also present with intrauterine growth restriction, resulting in low birth weight and short stature. Congenital heart defects, such as ventricular septal defects and other cardiac malformations, have been reported. Mild to moderate intellectual disability and developmental delays may occur in some affected individuals, though the severity varies considerably. There is no cure for fetal hydantoin syndrome, and management is supportive and symptom-based. Treatment may involve surgical correction of cleft lip/palate or congenital heart defects, early intervention programs for developmental delays, and educational support for children with learning difficulties. Prevention is the most important strategy, involving careful evaluation of the risks and benefits of phenytoin use during pregnancy and consideration of alternative anticonvulsant medications with lower teratogenic potential when possible. Genetic counseling is recommended for women of childbearing age who require antiepileptic therapy.

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