Prenatal diagnosis of mosaic trisomy 20 in New Zealand

Abstract

This series confirms a much lower incidence of phenotypic abnormalities associated with mosaic trisomy 20 compared to other forms of mosaic aneuploidy. Attempts to predict which of these pregnancies will have poor outcomes have not proven to be reliable. We recommend that, if a detailed anatomy scan is normal, parents be counselled that the risk of abnormality is less than 10%. Further tests should be performed only on the basis of a clinical indication.