Question

15. A newlywed husband and wife, who are both healthy, have just discovered through a genealogy website that they are second cousins. Which of the following disorders is somewhat more likely to occur in their children than in two people who are not related?

A. autosomal recessive diseases

B. autosomal dominant diseases

C. X-linked recessive diseases in their sons

D. X-linked dominant diseases in their sons

Answer 1

A. autosomal recessive diseases

Since both the parents are healthy and are not affected by either an autosomal dominant disorder,  X-linked dominant disorder or X-linked recessive disorder, there are chances that their children may have an autosomal recessive diseases. I am saying this because two unaffected and healthy people who may carry one copy of the mutated gene for an autosomal recessive disorder have a 25% risk of having a child affected by the disorder. For all the other mentioned disorders, either the father or mother must be affected by the disorder to carry it to their children.