Question

Recessive mutations in some rare genetic disorders can manifest as disease. A couple had four sons and four daughters, of which two sons developed such a genetic disorder. The parents did not manifest disease symptoms. Further studies shows that this disease affects only males. If genes $P$ (dominant allele) and $p$ (recessive allele) are involved in this disorder, identify the correct statement from the options given below.

• A. The genotype of the mother is $Pp$
• B. The genotype of the father is $PP$
• C. The gene $\left(P/p\right)$ is located on an autosome
• D. The gene $\left(P/p\right)$ is located on $Y$ chromosome

Answer 1

The correct option is A The genotype of the mother is $Pp$

The genotype of the parents should be Pp. They are carriers and so they do not show the symptoms. The couple will have children with genotypes PP, Pp and pp. As per the studies, the daughters are not affected. The sons with genotype pp are the affected/diseased ones while the sons with PP and Pp genotypes are normal.

Thus, the correct answer is option A.