NORD gratefully acknowledges Kimford J. Meador, MD, Professor, Department of Neurology & Neurological Sciences, Stanford Comprehensive Epilepsy Center, Stanford University School of Medicine, for assistance in the preparation of this report.
Fetal hydantoin syndrome is a characteristic pattern of mental and physical birth defects that results from maternal use of the anti-seizure (anticonvulsant) drug phenytoin (Dilantin) during pregnancy. The range and severity of associated abnormalities will vary greatly from one infant to another. However, characteristic features may include distinctive skull and facial features, growth deficiencies, underdeveloped (hypoplastic) nails of the fingers and toes, and/or mild developmental delays. Other findings occasionally associated with this syndrome include cleft lip and palate, a head circumference that is smaller than would be expected based upon an infant’s age and gender (microcephaly), and skeletal malformations particularly of the fingers or hands. The exact risk of a fetus developing fetal hydantoin syndrome is not fully understood, but only approximately 5-10% of fetuses exposed to phenytoin develop the disorder.Introduction
Anti-seizure medications, also known as antiepileptic or anticonvulsant medications are among the most common teratogens prescribed to women of childbearing age. A teratogen is a drug that interferes with the development of a fetus. Affected infants often develop similar symptoms regardless of the associated drug, particularly symptoms affecting the head and face region (craniofacial abnormalities). Studies have indicated that fetal valproate syndrome is associated with greater risk of neurological and cognitive abnormalities than other anti-seizure medications. NORD has a separate report on fetal valproate syndrome.
Although some disorders due to specific drugs (e.g. fetal hydantoin syndrome) are rare, many researchers believe that when considering the teratogenic effects of all antiepileptic drugs collectively these disorders are not rare. The concept of fetal antiepileptic syndromes in this regard is less useful than in the past and the broad consideration of the major and minor congenital malformations, various cognitive impairments, and behavioral abnormalities taken as a broader, collective concept is more appropriate.
Please note that some of these organizations may provide information concerning certain conditions potentially associated with this disorder.
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