Question

A woman and man have approached you for genetic counseling and are concerned about a hereditary form of deafness in their family. Both have normal hearing and there are no children. The woman's father has autosomal dominant sensory-neural deafness. Assume he is heterozygous. This hearing impairment displays onset at about age 10, and penetrance appears to be about 70%. There is no family history of deafness among the man's relatives. What is the probability that the woman is a carrier of the deafness allele

Answer 1

Answer:

35% is the probability that the woman is a carrier of the deafness allele

Explanation:

Both man and woman have normal hearing

Woman's father has autosomal dominant sensory-neural deafness - Dd

Genotype of heterozygous Woman's father = Dd

Let us assume that woman’s mother has normal hearing = dd

Dd * dd

Dd, Dd, dd, dd

Two deaf and two normal offspring.  

Since the penetration is of 70%, the probability of woman being a carrier is  

½ * 70% = 0.35