Question

the pedigree on the right shows the inheritance pattern for an x - linked recessive disorder. the mother of the individuals circled in pink is not shown on the pedigree. based on the phenotypes of these individuals and their father, what are the possible genotypes of their mother? check all of the boxes that apply.
□ ( x^a x^a )
□ ( x^a x^a )
□ ( x^a x^a )
done

Explanation:

1. The father of the pink - circled individuals is affected (green square), so his genotype is $X^{a}Y$ (since it's X - linked recessive, affected males have $X^{a}Y$).
2. The pink - circled females are carriers (half - shaded), meaning they have one normal allele ($X^{A}$) and one mutant allele ($X^{a}$), so their genotype is $X^{A}X^{a}$.
3. For a female to be a carrier ($X^{A}X^{a}$), she must inherit one $X^{A}$ from her mother and one $X^{a}$ from her father. But the father here is $X^{a}Y$, so the mother must provide the $X^{A}$ allele. Also, the fact that there are carriers (not all affected or all normal) implies the mother can be $X^{A}X^{A}$ (homozygous normal, will pass $X^{A}$ to daughters, and since father is $X^{a}Y$, daughters get $X^{A}$ from mother and $X^{a}$ from father, becoming carriers) or $X^{A}X^{a}$ (heterozygous carrier, can pass $X^{A}$ to daughters, and with father's $X^{a}$, daughters are carriers). The genotype $X^{a}X^{a}$ would make the mother affected, and if the mother was affected, the sons (the normal square in pink circle) would have to be affected (since they get X from mother), but the son is normal, so $X^{a}X^{a}$ is not possible.

Answer:

$\boldsymbol{X^{A}X^{A}}$, $\boldsymbol{X^{A}X^{a}}$ (Note: There was a typo in the original option, the correct carrier option is $X^{A}X^{a}$, and $X^{A}X^{A}$ is also a possible genotype for the mother)