Most common cause of Down syndrome is: (A) Robesonian translocation, (B) Mosaicism, (C) Meiotic nondisjuction, (D) Epigenetic mutation
Answer is C. Genetics of Down syndrome 95% cases - Meiotic nondisjunction of chromosome 21 occurring in the ovum 4% cases - Robesonian translocation 1% cases - Mosaicism resulting from mitotic nondisjunction of chr 21