Deafness is caused by recessive mutations in any one of at least five genes. Two deaf individuals have nine children, all of whom have normal hearing. Which of the following can you conclude?
A)The parents have mutations in the same gene.
B)The parents have mutations in different genes.
C)An epistatic interaction has occurred.
D)The mutations are codominant to the normal allele.
E)The mutations are incompletely dominant to the normal allele.

Question

Quizplus · Accepted Answer

If the parents had mutations in the same gene, all of their children would inherit at least one mutated copy of the gene and would therefore have a 25% chance of being deaf. Since all of their children have normal hearing, it is more likely that the parents have mutations in different genes. This would mean that each parent is heterozygous for a different deafness-causing mutation and the normal allele masks the effects of the mutations in their children. An epistatic interaction, codominance, or incomplete dominance would not explain the observed pattern of inheritance.

Deafness Is Caused by Recessive Mutations in Any One of at Least