Multiple congenital anomalies in a child born after prenatal diagnosis of trisomy 20mosaicism

The clinical significance of trisomy 20 mosaicism in amniotic fluid cultures has remained unclear so far. We report data on a child with multiple congenital anomalies born after a diagnosis of true trisomy 20 mosaicism in 65% of amniotic fluid cells. The child had generalized dysmorphic features, including facial dysmorphy resembling those of a child with Williams syndrome. The boy also had hypotonia and language delay. Although most of the published cases do not mention any abnormalities in children born after prenatal diagnosis of trisomy 20 mosaicism, the distinct cranio-facial features and the similarities to previous reports of partial or complete chromosome 20 mosaicism raises the possibility that a recognizable pattern of malformation might be associated with the prenatally diagnosable condition in some cases.