Question

if sally marries a man who is an asymptomatic carrier for alkaptonuria, what is the probability that they would have a son with alkaptonuria

Answer 1

Alkaptonuria is passed down through the generations as an autosomal recessive condition. When an individual receives the same faulty gene for the same trait from both parents, they are said to have recessive genetic diseases. If a person is born with one normal gene and one illness gene, he or she will be a carrier for the disease but will not display symptoms. With each pregnancy, there is a 25% chance that two carrier parents will both carry the faulty gene and, as a result, have an afflicted child. With each pregnancy, there is a 50% chance of having a child who is a carrier like the parents. A child's chance of receiving normal genes from both parents and being genetically normal for that attribute is 25%.

The risk is the same for males and females alike.