Question

which allele combination represents a male who has an x - linked recessive disorder?
○ x^ry
○ x^ry
○ x^rx^r
○ x^rx^r

Explanation:

• Males have the sex - chromosome combination \(XY\).
• For an X - linked recessive disorder, the allele on the X - chromosome must be recessive. Let the recessive allele be represented as \(X^{r}\).
• So the allele combination for a male with an X - linked recessive disorder is \(X^{r}Y\).
• \(X^{R}Y\) represents a male with the dominant allele (so no disorder). \(X^{r}X^{r}\) is a female (two X - chromosomes) with the recessive disorder. \(X^{R}X^{r}\) is a female (two X - chromosomes) who is a carrier (heterozygous).

Answer:

\(X^{r}Y\) (the first option)