Glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as an X-linked recessive allele in humans. A woman whose father suffered from G6PD marries a normal man. What proportion of their sons is expected to be G6PD?
A) 100%
B) 1/4
C) 1/2
D) zero

Question

Quizplus · Accepted Answer

Since the woman is a carrier of the G6PD gene, her genotype is XGXg. Her normal husband's genotype is XNY. The possible gametes of the woman are XG and Xg, while the husband's are XN and Y. The sons will receive one X from the mother and one Y from the father. The daughters will receive one X from each parent.
The possible genotypes of their children are: XGXN, XgXN, XGXy, and XgXy. Only the XGXy and XgXy genotype will result in G6PD deficiency. Therefore, the probability of having a son with G6PD deficiency is 50%.

Glucose-6-Phosphate Dehydrogenase Deficiency (G6PD) Is Inherited as an X-Linked Recessive