Genetic Concepts for Medical-Surgical Nursing
(Concepts for Interprofessional Collaborative Care
, Genetic Concepts for Medical-Surgical Nursing
(Concepts for Interprofessional Collaborative Care
Chapter 05: Genetic Concepts for Medical-Surgical Nursing
MULTIPLE CHOICE
1. 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?
a. Females have a decreased penetrance rate for this gene mutation and are therefore less likely to express the
trait.
b. Females have two X chromosomes and one is always inactive. This inactivity decreases the effect of the
gene.
c. The incidence of X-linked recessive disorders is higher in males because they do not have a second X
chromosome to balance expression of the gene.
d. Males have only one X chromosome, which allows the X-linked recessive disorder to be transmitted from
father to son.
ANS: C
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.
2. A client is typed and crossmatched for a unit of blood. Which statement by the nurse indicates a need for
further genetic education?
a. Blood type is formed from three gene alleles: A, B, and O.
b. Each blood type allele is inherited from the mother or the father.
c. If the clients blood type is AB, then the client is homozygous for that trait.
d. If the client has a dominant and a recessive blood type allele, only the dominant will be expressed.
ANS: C
There are three possible gene alleles: A, B, and O. Blood type is determined by only two of the three specific
gene alleles. The blood type OO is homozygous in contrast to the blood type AB, which is heterozygous. In the
blood type AO, the gene allele A is dominant and will be expressed as blood type A. It is true that each blood
type allele is inherited from the mother or the father.
3. A nurse cares for a client of Asian descent who is prescribed warfarin (Coumadin). What action should the
nurse perform first?
a. Schedule an international normalized ratio (INR) test to be completed each day.
b. Initiate fall precautions and strict activity limitations.
c. Teach the client about bleeding precautions, including frequent checks for any bruising.
d. Confirm the prescription starts warfarin at a lower-than-normal dose.
ANS: D
Most individuals of Asian heritage have a single nucleotide polymorphism in the CYP2C19 gene that results in
(Concepts for Interprofessional Collaborative Care
, Genetic Concepts for Medical-Surgical Nursing
(Concepts for Interprofessional Collaborative Care
Chapter 05: Genetic Concepts for Medical-Surgical Nursing
MULTIPLE CHOICE
1. 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?
a. Females have a decreased penetrance rate for this gene mutation and are therefore less likely to express the
trait.
b. Females have two X chromosomes and one is always inactive. This inactivity decreases the effect of the
gene.
c. The incidence of X-linked recessive disorders is higher in males because they do not have a second X
chromosome to balance expression of the gene.
d. Males have only one X chromosome, which allows the X-linked recessive disorder to be transmitted from
father to son.
ANS: C
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.
2. A client is typed and crossmatched for a unit of blood. Which statement by the nurse indicates a need for
further genetic education?
a. Blood type is formed from three gene alleles: A, B, and O.
b. Each blood type allele is inherited from the mother or the father.
c. If the clients blood type is AB, then the client is homozygous for that trait.
d. If the client has a dominant and a recessive blood type allele, only the dominant will be expressed.
ANS: C
There are three possible gene alleles: A, B, and O. Blood type is determined by only two of the three specific
gene alleles. The blood type OO is homozygous in contrast to the blood type AB, which is heterozygous. In the
blood type AO, the gene allele A is dominant and will be expressed as blood type A. It is true that each blood
type allele is inherited from the mother or the father.
3. A nurse cares for a client of Asian descent who is prescribed warfarin (Coumadin). What action should the
nurse perform first?
a. Schedule an international normalized ratio (INR) test to be completed each day.
b. Initiate fall precautions and strict activity limitations.
c. Teach the client about bleeding precautions, including frequent checks for any bruising.
d. Confirm the prescription starts warfarin at a lower-than-normal dose.
ANS: D
Most individuals of Asian heritage have a single nucleotide polymorphism in the CYP2C19 gene that results in
