Trisomy 21 mosaicism in a woman with two children with trisomy 21 Down's syndrome.

Trisomy 21 mosaicism in a woman with two children with trisomy 21 Down's syndrome* Summary. Trisomy 21 mosaicism was identified by fluorescent quinacrine banding in a phenotypically normal mother, who gave birth to two children with trisomy 21 Down's syndrome. Trisomy 21 Down's syndrome associated with maternal mosaicism was first described by Smith et al in 1962. Since then there have been at least eight more reported cases of trisomy 21 Down's syndrome associated with maternal trisomy 21 mosaicism (reviewed by Aarskog, 1969). Similarly, paternal mosaicism has resulted in children with Down's syndrome (Hsu et al, 1971; Mehes, 1973). We have recently detected another phenotypically normal mother with mosaicism through her two children who had trisomy 21 Down's syndrome.