Question

An abnormal human baby with 'XXX' allosome genotype was born due to

• A. Fusion of 2 ova and 1 sperm
• B. Fusion of 2 sperms and 1 ova
• C. Formation of abnormal sperms in father
• D. Formation of abnormal ova in mother

Answer 1

The correct option is D Formation of abnormal ova in mother

Baby has extra X chromosome, thus it must have been produced by fusion of XX ovum with normal X sperm.
In males abnormal sperms possible are XY and O.
If fusion of multiple gametes had occured, then baby would have had triploid genotype not trisomy.