Cytogenetic analysis of Down syndrome in Gujarat.

During 1995 to 2006, 382 cases clinically suspected for Down syndrome were investigated for cytogenetic study. Free trisomy 21 constituted 84.8% of cases, translocation 8.9%, mosaic 3.9% and in 2.4% cases regular T21 was associated with structural or numerical changes. Translocation was parentally inherited in 26.5% cases and maternal transmission was twice as common as paternal. Males were more pronounced to be affected than females in all the groups. 91.6% of DS babies were born to younger mothers (20-35 yr) compared to 8.4% in elderly mothers (>35 yr).