A nurse is educating a client about genetic screening.The client asks why red-green color blindness,an X-linked recessive disorder noted in some of her family members,is expressed more frequently in males than females.How should the nurse respond?

Question

Quizplus · Accepted Answer

Because the number of X chromosomes in males and females is not the same (1:2),the number of X-linked chromosome genes in the two genders is also unequal.Males have only one X chromosome,a condition called hemizygosity,for any gene on the X chromosome.As a result,X-linked recessive genes have a dominant expressive pattern of inheritance in males and a recessive expressive pattern of inheritance in females.This difference in expression occurs because males do not have a second X chromosome to balance the expression of any recessive gene on the first X chromosome.It is incorrect to say that one X chromosome of a pair is always inactive in females,or that females have a decreased penetrance rate for this gene mutation.X-linked recessive disorders cannot be transmitted from father to son,but the trait is transmitted from father to all daughters who will be carriers.

A Nurse Is Educating a Client About Genetic Screening