Down syndrome due to 21;21 translocation in a male twin

A spontaneous 21;21 translocation resulting in features consistent with Down syndrome is reported in the first born of male fraternal twins. No history of twinning or chromosomal abnormalities in the family was noted. Any association between dizygous twinning and Down syndrome due to de novo translocation remains speculative until a sufficient pool of published data is available from study of such families.