Kamlesh, a 2 year old girl, has Down's syndrome. Her karyotype is 21/21 translocation. What is the risk ofrecurrence in subsequent pregnancies if the father is a balanced translocation carrier :
(A) 100% (B) 50% (C) 25% (D) 0%
(A) Down Syndrome– (Trisomy 21)

Seen in 11n 800 to 1000 newborns
M/C Nonlethal trisomy
Risk of Down syndrome increases with increase in maternal age
At maternal age of 35 years, the risk of having a baby with Down syndrome is 1:365. to 1:400.

Recurrent Risk of Down’s syndrome