Most common chromosomal syndrome is?: (A) Fragile X-syndrome, (B) Trisomy 17, (C) Trisomy 21, (D) Trisomy 13
Answer is C. Ans. is 'c' i.e., Trisomy 21 Down syndrome (Trisomy) is the most common of the chromosomal disorder. It occurs in frequency of 1:800 to 1:1000 newborn.