Abnormal first trimester screen in partial deletion of chromosome 6p21: a case-report.

In this case-report we describe a 21-year-old primigravida with an abnormal first trimester screen: combined risk for Downs Syndrome was 1:90. Karyotype revealed 46,XX,del(6)(p21). Termination with Cytotec was offered because of the risk of congenital malformations and subsequent abnormalities associated with deletions in chromosome 6p. As to our knowledge no report has been written about the prenatal diagnosis of deletions on the short arm of chromosome six based on the first trimester screen. By publishing our experience we want to create awareness. This case-report shows the importance of combining prenatal screening with the biochemical tests, instead of only measuring nuchal translucency. It also shows the need for full karyotyping when invasive prenatal testing is done.