Data on selected malformations in the EUROCAT study

In the context of the EUROCAT study data on selected congenital malformatio ns and chromosome aberrations were collected from the Canton of: Zurich (19 88-1997). It was found that the major proportion of severe and early malfor mations, such as anencephalus and holoprosencephaly were detected prenatall y; for oral clefts and meningomyeloceles this was not the case, at any rate in regard to isolated (non-syndromic) malformations. However, if these def ects occur in combination with a chromosome aberration, the likelihood of s uch a case being registered is higher For the same reason, i.e. due to abno rmal ultrasound findings and intrauterine growth retardation, trisomies 13 and 18 were more often detected prenatally than trisomy 21.