Phenylketonuria PKU is an inherited disorder that can lead t

Phenylketonuria (PKU) is an inherited disorder that can lead to mental issues if left untreated. PKU is inherited in an autosomal recessive manner. What is the chance that the boy marked with a \"?\" in the pedigree will have PKU? 1/2 1/3 1/4 1/6 1/8

Solution

Answer is (A) 1/2

Because it is autosomal recessive disorder which needs both alleles to be recessive to become PKU patient. Also all the people looks normal are heterozygous for the PKU gene SSO they will contribute to PKU along with affected people to next progeny(?).

So there is a chances of 50% to become PKU