Trisomy 18 mosaicism in a mildly retarded boy with postnatal overgrowth.

Abstract

We report a 6-year-old mildly retarded boy with trisomy 18 in 44% of peripheral lymphocytes. He had mild nonspecific dysmorphic features, microcephaly, micropenis with cryptorchidism and postnatal overgrowth. Trisomy 18 mosaicism was confirmed by a fluorescent in situ hybridization study. Ten previous reports of trisomy 18 mosaicism with normal or subnormal intelligence have been described but only one case of trisomy 18 mosaicism with high stature has been reported.