[Genetic counseling and prenatal diagnosis in families with neural tube defects].

An analysis of 141 families with children with neural-tube defects was performed. The families were consulted in the Department of Genetics, the Institute of Mother and in Child the period between 17.01.1978 and 29.02.1980. The family histories were obtained from the parents. The diagnosis was established on the basis of autopsy data and/or medical records. In cases of multiple congenital malformations coexisting with a neural-tube defect the precise diagnosis of the syndrome was established after a thorough search of the medical literature. Analysis of the material, showed that in 10 families (6,5%) neural-tube defect was associated with other malformations. There were 5 cases of sporadic syndromes (cloacal extrophy-2, aberrant tissue bands-2, sacrococageal teratoma-1), 3 families with Meckel's syndrome and 2 cases in which the nature of the syndrome was not determined. In 131 families the neural-tube defect was isolated and multifactorial inheritance was assumed (table VII). 113 families were given information about the cause of malformation, risk of recurrence, possibility of prenatal diagnosis and indications for amniocentesis (estimation of alpha-foetoprotein in amniotic fluid). After receiving genetic counseling and being fully informed about prenatal diagnosis the parents were asked about their procreative plans and their attitude to amniocentesis. Out of these families 74,3% planned next pregnancy (table IX), 57,6% wanted to have prenatal diagnosis (table VI). 131 family histories (probands with isolated neural-tube defect) were reviewed to determine recurrence risk for relatives. The recurrence risk for sibs was found to be: 4,9% (table III) and was higher than the expected risk (3,4%) from the population incidence of neural-tube defects in Poland (1, 15/1000 births including stillbirths). The recurrence risk for second and third degree relatives was found to be 0,1% (table IV) and 0,3% (table V) respectively.