Question

hemophilia is a sex linked recessive genetic disorder in humans. the genes associated with the disorder are located on the x chromosome (x^h). females carrying a defective allele on x chromosome are carriers while males with a similar condition are hemophiliacs.
which genotypes are possible for the parents of a hemophiliac female?
○ male parent: x^hy; female parent: x^hx^h
○ male parent: x^hy; female parent: x^hx^h
○ male parent: x^hy; female parent: x^hx^h
○ male parent: x^hy; female parent: x^hx^h

Explanation:

• Hemophilia is a sex - linked recessive disorder. A female with hemophilia has the genotype \(X^{h}X^{h}\).
• For a female to have \(X^{h}X^{h}\), she must receive an \(X^{h}\) from each parent.
• Males have the genotype \(X^{h}Y\) (hemophilic) or \(X^{H}Y\) (normal). Since the father must give an \(X^{h}\) to his daughter (to make \(X^{h}X^{h}\)), the father's genotype is \(X^{h}Y\).
• Females have genotypes \(X^{H}X^{H}\) (normal), \(X^{H}X^{h}\) (carrier), or \(X^{h}X^{h}\) (hemophilic). Since the mother must give an \(X^{h}\) to her daughter, and if we assume the mother is not hemophilic (as the options don't have two hemophilic parents in most cases), the mother's genotype is \(X^{H}X^{h}\) (a carrier).

Answer:

male parent: \(X^{h}Y\); female parent: \(X^{H}X^{h}\)