The deficiency of the enzyme glucose- 6- phosphate dehydrogenase G6PD is inherited as a recessive gene on the X chromosome in humans.A phenotypically normal woman whose father had G6PD is married to a normal man.What fraction of their sons would be expected to have G6PD?
A)1/3
B)zero
C)1/2
D)100%
E)1/4

Question

Quizplus · Accepted Answer

Since G6PD deficiency is X-linked and the woman's father had it, she must carry one copy of the gene (being heterozygous). The normal man can only contribute a Y chromosome to sons, so sons inherit their X chromosome from their mother. Therefore, there's a 50% chance a son will inherit the affected X chromosome.

The Deficiency of the Enzyme Glucose- 6- Phosphate Dehydrogenase G6PD