Hereditary factors in the etiology of neural tube defects. Results of a survey.

Ongoing research in the etiology of neural tube defects is increasingly being directed towards the molecular mechanisms at work in the formation of these complex lesions. We undertook to review the family history of patients in a large myelomeningocele/spina bifida clinic in an effort to identify genetic trends in these families, particularly as they relate to current research efforts and laboratory models. Surveys were received from 363 patients (35.5% of the clinic population) and analyzed. The myelomeningocele recurrence rate was 4.3%. Seven sets of twins were identified and all were discordant for their spinal lesions. A family history of spina was found to be evenly distributed between maternal and paternal relatives, rather than tending to follow through the maternal side. Epilepsy was more commonly found on the maternal side of the family, most likely reflecting the postulated causal relationship between maternal anticonvulsant use and the occurrence of spina bifida, although also possibly supporting the concept that a genetic predisposition for maternal epilepsy may also be associated with a higher frequency of birth defects among children of epileptics, independent of anticonvulsant use. Patients with spina bifida in the setting of Waardenburg syndrome and fragile X syndrome were also identified and will be discussed.