title: Sib risk of neural tube defect: is prenatal diagnosis indicated in pregnancies following the birth of a hydrocephalic child?
abstract: Recurrence frequencies of central nervous system malformations in sibs of probands with anencephalus or spina bifida range between 1% and 7%. The frequency of hydrocephalus among sibs of such probands is low (0.21%) but, nevertheless, is increased 2 to 5-fold when compared to general population frequencies. Anencephalus and spina bifida cystica were observed in 1.65% of sibs of children with hydrocephalus, a 2- to 8-fold increased over the population frequencies. These data indicate that some aetiological factors may be common to all three malformations. The risk figure of 1.65% for anencephalus and spina bifida in sibs born after the birth of a hydrocephalic proband constitutes sufficient indication for prenatal diagnosis by alphafetoprotein determination of the amniotic fluid.
mesh_terms: D000757:Anencephaly / Q000235:genetics; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000235:genetics; D009436:Neural Tube Defects / Q000235:genetics*; D011247:Pregnancy; D011296:Prenatal Diagnosis; D012008:Recurrence; D012306:Risk; D016136:Spina Bifida Occulta / Q000235:genetics