Question

What is the genetic status of a female who carries one X-linked recessive allele but does not express the trait?

Options

• An affected individual with incomplete penetrance

• A homozygous recessive individual

• A homozygous dominant individual

• A carrier

Answer 1

A female with one recessive allele and one dominant allele on her X chromosomes is called a carrier. She does not express the recessive trait because the dominant allele masks it, but she can pass the recessive allele to her offspring. Carriers are heterozygous for the X-linked trait.