Prenatal diagnosis of tetrasomy 9p in a 19‐week‐old fetus with Dandy–Walker malformation: a case report

Objective The presentation of sonographic and perinatal findings of tetrasomy 9p. Methods and Results Chorionic villus sampling and amniocentesis were performed at 19 weeks of gestation because of the sonographic findings of Dandy–Walker malformation with bilateral ventriculomegaly. Cytogenetic analysis showed 47,XX,+i psu dic(9)(pter->q12::q12>-pter). The pregnancy was terminated at 20 weeks of gestation at the request of the parents. At post-mortem examination, the presumed hypoplasia of the vermis could not be confirmed for technical reasons. No other pathological findings were seen. Conclusion From our experience and from the literature, we conclude that Dandy–Walker malformation is an important finding in tetrasomy 9p. Chromosomal studies should be carried out in fetuses with sonographically detected Dandy–Walker malformation, even in the absence of other abnormalities. Copyright © 2004 John Wiley & Sons, Ltd.