Translocation Down syndrome.

Cytogenetic investigations carried out on 1021 cases of Down syndrome revealed translocation in 46 cases. The most frequent was of t(14;21) and t(21;21) types. Most of the translocation DS cases (n = 31) were born to younger mothers (< 25 years), when compared to pure trisomy 21 DS cases. Parental karyotypes, family history and parental ages has helped us greatly in offering genetic counseling, prenatal diagnosis and estimating the risk for the next conception.