Question

who has hemophilia in the pedigree that is shown?
john and ann
fred and luke
john, charles, jack, and irene
ann and marie

Explanation:

In a pedigree for X - linked recessive disorders like hemophilia, affected males have the genotype \(X^{h}Y\) (purple squares) and carriers are heterozygous females (\(X^{H}X^{h}\), half - purple circles). Looking at the pedigree: Fred (purple square, \(X^{h}Y\)) and Luke (purple square, \(X^{h}Y\)) have the affected male genotype. Other options: John (not shown as affected), Ann (not in the relevant affected form), Charles (white square, normal), Jack (white square, normal), Irene (white circle, normal), Marie is a carrier (half - purple), not affected.

Answer:

Fred and Luke