Question

Polydactyly is expressed when an individual has extra fingers and/or toes. Assuming 50% 47) penetrance, a man with six fingers on each hand and six toes on each foot marries a woman with a normal number of digits. Having extra digits is caused by a dominant autosomal allele. The couple has a son with normal hands and feet, but the coupleʹs second child has extra digits. What is the probability that their next child will have polydactyly?

Answer 1

Answer:

1/2

Explanation:

Father: is a heterozygote for this trait . Meiosis: 1/2 is the frequency for the normal allele

Mother: has two recessive alleles  (i.e., doesn't have the trait). Meiosis: 2/2 is the frequency for the normal allele  

In consequence, the probability of having polydactyly is: (1/2) x (2/2): 1/2