Your browser does not support javascript:   Search for gard hereSearch for news-and-events here.


Genetic and Rare Diseases Information Center (GARD)

Print friendly version

Fetal hydantoin syndrome

Other Names for this Disease
  • Dilantin Embryopathy
  • Phenytoin Embryopathy
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.


What is fetal hydantoin syndrome?

What are the signs and symptoms of fetal hydantoin syndrome?

What is fetal hydantoin syndrome?

Fetal hydantoin syndrome is a disorder that is caused by exposure of a fetus to phenytoin, a drug commonly prescribed for epilepsy. Not all infants exposed to phenytoin will be affected with the disorder. Symptoms in affected individuals may include abnormalities of the skull and facial features, growth deficiencies, underdeveloped nails of the fingers and toes, and/or mild developmental delays. Other findings occasionally associated with this syndrome include cleft lip and palate, having an abnormally small head (microcephaly) and brain malformations with more significant developmental delays.[1] Treatment may include surgery for cleft lip and palate and special education and related services for children with learning delays. Other treatment is symptomatic and supportive.[1]
Last updated: 8/10/2011

What are the signs and symptoms of fetal hydantoin syndrome?

There is a wide range in the nature and severity of characteristics associated with fetal hydantoin syndrome. Of infants born to women who used phenytoin during pregnancy, 10-30% are reported to show some of the characteristics associated with this syndrome. Few infants exposed only to phenytoin have all of the characteristic that have been reported.[2]

Children with this condition may be small at birth, with increased hair on the body and face, and with poorly developed fingernails and toenails.[1] They may also have poor muscle tone.[1] Facial features that may be present with this syndrome include a flat bridge of the nose; an underdeveloped vertical groove in the center of the upper lip (philtrum); a large mouth; and malformed ears. Features specific to the eyes may include down-slanted eyes; widely spaced eyes (hypertelorism); crossed eyes (strabismus); drooping eyelids (ptosis); and/or epicanthal folds (skin folds of the eyelid covering the inner corner of the eye). Other features that have been reported include a short or webbed neck and low-set hair line.[1][3] Growth deficiencies may include underdeveloped fingers and/or toes, malformed nails, as well as finger-like thumbs.[1]

These features are often associated with growth delay and varying degrees of developmental delay. The risk for an affected child to be neurologically impaired is estimated at 1 to 11 % (two to three times higher than for the general population). The risk of cleft lip and/or palate and heart defects is estimated to be about five times higher among exposed infants. Some case reports have suggested an increased risk for the occurrence of benign (noncancerous) or malignant (cancerous) tumors, such as neuroblastoma or other neonatal tumors (ependymoma, ectodermal tumors, Wilms tumor).[3]
Last updated: 8/10/2011

  1. Fetal Hydantoin Syndrome. NORD. April 25, 2008; Accessed 8/9/2011.
  2. Aaron B Caughey. Seizure Disorders in Pregnancy. eMedicine. June 28, 2011; Accessed 8/10/2011.
  3. E. Robert-Gnansia. Fetal hydantoin syndrome. Orphanet. February 2006; Accessed 8/10/2011.