Mosaicism for Trisomy 17–18 and Trisomy 13–15 in Man

Abstract

TRISOMY for two chromosomes of the normal chromosome complement has been found in several human subjects. The chromosomes most often involved in these double trisomic states have been the X-chromosome^1,2 and chromosomes of the pairs 13–15³, 17–18^1,4 and 21^2–4. In addition, male subjects with 48 chromosomes have been described in whom one extra chromosome was an X-chromosome, giving the sex chromosome constitution XXY, together with true trisomy for an autosome^5,6. Hitherto, trisomies 13–15 and 17—18 have not been found in one individual and all the reported cases of double trisomy have apparently had only one cell line.