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

Abstract

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.