Hemophilia A is an X-linked recessive mutation in humans. If a couple gives birth to a daughter with hemophilia A, which of the following may be the genotype of the parents?

a. XCXC and XCY

b. XCXC and XcY

c. XCXc and XcY

d. XcXc and XCY

c. XCXc and XcY

Explanation:

Hemophilia is an X linked recessive disorder. The disease follows criss-cross inheritance. A hemophiliac father and hemophiliac or carrier mother can have a hemophiliac daughter. To have an affected daughter (X^cX^c) both the parents should have at least one copy of the X^c chromosome to pass it to the daughter. The parental genotypes "XCXc and XcY" have one copy of X^c in both the parents and therefore can have a hemophiliac daughter.