If a female heterozygous for G542X has a child with a male heterozygous for ΔF508, what is the probability that the child would be homozygous for G542X?

• A. 0.00
• B. 0.25
• C. 0.75
• D. 1.00

Answer: (A)

To determine the probability that a child would be homozygous for the G542X mutation when one parent is heterozygous for G542X and the other parent is heterozygous for ΔF508, it's important to understand the inheritance patterns of these alleles.

The female parent has the genotype G542X/g, representing one copy of the G542X mutation and one normal allele (g). The male parent has the genotype ΔF508/g, which consists of one copy of the ΔF508 mutation and one normal allele (g). The G542X and ΔF508 mutations are both associated with cystic fibrosis and are located on different alleles of the CFTR gene.

To analyze the potential offspring genotypes, we can set up a Punnett square based on the possible alleles each parent can pass on:

1. The female can pass on either G542X or g.

2. The male can pass on either ΔF508 or g.

The possible combinations from these allele pairings would result in the following offspring genotypes:

• G542X/ΔF508

• G542X/g

• g/ΔF508

• g/g

From this analysis, it is clear that the child