Question

Jane and John are considering having another child. Given the pedigree you constructed and the mode of inheritance for galactosemia, what is the risk that their next child will have the disorder?

a. 1/4 (because they are both heterozygotes)
b. 0 (because they already have one child with the disorder)
c. 3/4 (because they are both heterozygotes)
d. 1/16 (because they each have 1/4 chance of passing on the allele)

Answer 1

Answer:

a. 1/4 (because they are both heterozygotes)

Explanation:

A Punnett square two heterozygous (Gg) parents states that every child would have 1/4 chance of receiving the gg allele combination, resulting galactosemia .

Offsprings genotype probabilities are as follows :

1/4 GG (25%)

1/2 Gg (50%)

1/4 gg (50%)

                G            g

G          |   GG      |   Gg

g           |   Gg      |   gg