In a family, a man with hemophilia, a genetic disorder where blood doesn't clot properly, marries a woman who is a carrier of the gene but does not express the disorder. What is the probability that their son will have hemophilia?
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Hemophilia is an X-linked recessive disorder. In such disorders, sons inherit their X chromosome from their mother and the Y chromosome from their father.
Step 1: Hemophilia Inheritance. Hemophilia is an X-linked recessive condition. Affected males have the genotype \(X^hY\), and carrier females have the genotype \(X^HX^h\).Step 2: Genetic Cross Analysis. A Punnett square illustrates the potential offspring genotypes:\[\begin{array}{c|c|c} & X^h & Y \hlineX^H & X^HX^h & X^HY X^h & X^hX^h & X^hY \end{array}\]The cross yields the following outcomes: \(X^HY\): Unaffected son. \(X^hY\): Son with hemophilia. \(X^HX^h\): Carrier daughter. \(X^hX^h\): Daughter with hemophilia.Step 3: Probability of an Affected Son. One out of two male offspring (\(X^hY\)) will inherit hemophilia. The probability is therefore:\[\text{Probability} = \frac{1}{2} = 50\%.\]\[\therefore \text{The correct answer is: 50\%.}\]