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.

XAXA

XaXa

XAXa

Answer 1

The right answers are : XAXA and XAXa.

A genetic disease is referred to as X-linked recessive inheritance when:

* the gene involved in the mutation is on the sex chromosome X

* the mutation is recessive, a man carrying the mutant allele will be ill, because hemizygote for the X chromosome. The presence of both mutant alleles is necessary for the disease to be expressed in a girl.

According to the image, the mother has always transmitted a healthy allele (XA) so the answers are the genotypes carrying this allele.

Answer 2

Based on the phenotypes of the individuals shown in pink and that of their father, the possible genotype of their mother would be XAXA and XAXa.

XAXA and XAXa are the only logical options because:

• The female children are heterozygous because they are half-shaded in the pedigree. This means that only one of their two X chromosomes is affected.
• Out of the two X chromosomes of a female, one is always from the father and the other from the mother.
• Since the X chromosome of the father is affected for the X-linked disorder, his daughters will always inherit an affected X chromosome from him.
• If the mother is affected for the disorder, their second X chromosomes would also be affected and they will be phenotypically affected for the disorder

Hence, the only way the daughters can inherit an unaffected chromosome from the mother is if she is is totally free from the disorder, XAXA, or a carrier, XAXa.

More on X-linked disorders can be found here: https://brainly.com/question/14984347