Question

which allele combination represents a female who is a carrier for an x - linked recessive disorder?\
\\( x^r x^r \\)\
\\( x^r x^r \\)\
\\( x^r y \\)\
\\( x^r y \\)

Explanation:

1. For X - linked recessive disorders, females have two X chromosomes (\(XX\)) and males have one X and one Y (\(XY\)). So we can eliminate options with \(Y\) ( \(X^{R}Y\) and \(X^{r}Y\) ) as they represent males.
2. A carrier for an X - linked recessive disorder is a female who has one normal (dominant, \(X^{R}\)) allele and one mutant (recessive, \(X^{r}\)) allele. The genotype \(X^{r}X^{r}\) would represent a female with the disorder (homozygous recessive), while \(X^{R}X^{r}\) means she has one dominant and one recessive allele, making her a carrier.

Answer:

A. \(X^{R}X^{r}\)