Chapter 06: Genetics, Conception, and Fetal Development
Perry: Maternal Child Nursing Care, 6th Edition
1. 1. A father and mother are carriers of phenylketonuria (PKU). Their 2-year-
old daughter has PKU. The couple tells the nurse that they are planning to
have a second baby. Because their daughter has PKU, they are sure that
their next baby won't be affected. What response by the nurse is most
accurate?
a. "Good planning; you need to take advantage of the odds in your favor."
b. "I think you'd better check with your doctor first."
c. "You are both carriers, so each baby has a 25% chance of being affected."
d. "The ultrasound indicates a boy, and boys are not affected by PKU.":
ANS:
C
The chance is one in four that each child produced by this couple will be affected
by PKU disorder. This couple still has an increased likelihood of having a child
with PKU. Having one child already with PKU does not guarantee that they will not
have another. These parents need to discuss their options with their physician.
However, an opportune time has presented itself for the couple to receive correct
teaching about inherited genetic risks. No correlation exists between gender and
inheritance of the disorder because PKU is an autosomal recessive disorder.
2. 2. The nurse is providing genetic counseling for an expectant couple who
already have a child with trisomy 18. The nurse should:
a. tell the couple they need to have an abortion within 2 to 3 weeks.
b. explain that the fetus has a 50% chance of having the disorder.
c. discuss options with the couple, including amniocentesis to determine
whether the fetus is affected.
d. refer the couple to a psychologist for emotional support.: ANS: C
Genetic testing, including amniocentesis, would need to be performed to determine
whether the fetus is affected. The couple should be given information about the
likelihood of having another baby with this disorder so that they can make an
informed decision. A genetic counselor is the best source for determining genetic
probability ratios. The couple eventually may need emotional support, but the status
of the pregnancy must be determined first.
3. 3. The nurse is assessing the knowledge of new parents with a child born
with maple syrup urine disease (MSUD). This is an autosomal recessive
inherited disorder, which means that:
a. both genes of a pair must be abnormal for the disorder to be expressed.
, Chapter 06: Genetics, Conception, and Fetal Development
Perry: Maternal Child Nursing Care, 6th Edition
b. only one copy of the abnormal gene is required for the disorder to be
expressed.
c. the disorder occurs in males and heterozygous females.
d. the disorder is carried on the X chromosome.: ANS: A
MSUD is a type of autosomal recessive inheritance disorder in which both genes of
a pair must be abnormal for the disorder to be expressed. MSUD is not an X-linked
dominant or recessive disorder or an autosomal dominant inheritance disorder.
4. 4. In presenting to obstetric nurses interested in genetics, the genetic nurse
identifies the primary risk(s) associated with genetic testing as: a. anxiety and
altered family relationships.
b. denial of insurance benefits.
c. high false-positive results associated with genetic testing.
d. ethnic and socioeconomic disparity associated with genetic testing.: ANS:
B
Decisions about genetic testing are shaped by socioeconomic status and the
ability to pay for the testing. Some types of genetic testing are expensive and are
not covered by insurance benefits. Anxiety and altered family relationships, high
false-positive results, and ethnic and socioeconomic disparity are factors that may
be difficulties associated with genetic testing, but they are not risks associated
with testing.
5. 5. A man's wife is pregnant for the third time. One child was born with cystic
fibrosis, and the other child is healthy. The man wonders what the chance is
that this child will have cystic fibrosis. This type of testing is known as: a.
occurrence risk.
b. recurrence risk.
c. predictive testing.
d. predisposition testing.: ANS: B
The couple already has a child with a genetic disease so they will be given a
recurrence risk test. If a couple has not yet had children but are known to be at risk
for having children with a genetic disease, they are given an occurrence risk test.
Predictive testing is used to clarify the genetic status of an asymptomatic family
member. Predisposition testing differs from presymptomatic testing in that a positive
result does not indicate 100% risk of a condition developing.
6. 6. A key finding from the Human Genome Project is:
a. approximately 20,500 genes make up the genome.
b. all human beings are 80.99% identical at the DNA level.
Perry: Maternal Child Nursing Care, 6th Edition
1. 1. A father and mother are carriers of phenylketonuria (PKU). Their 2-year-
old daughter has PKU. The couple tells the nurse that they are planning to
have a second baby. Because their daughter has PKU, they are sure that
their next baby won't be affected. What response by the nurse is most
accurate?
a. "Good planning; you need to take advantage of the odds in your favor."
b. "I think you'd better check with your doctor first."
c. "You are both carriers, so each baby has a 25% chance of being affected."
d. "The ultrasound indicates a boy, and boys are not affected by PKU.":
ANS:
C
The chance is one in four that each child produced by this couple will be affected
by PKU disorder. This couple still has an increased likelihood of having a child
with PKU. Having one child already with PKU does not guarantee that they will not
have another. These parents need to discuss their options with their physician.
However, an opportune time has presented itself for the couple to receive correct
teaching about inherited genetic risks. No correlation exists between gender and
inheritance of the disorder because PKU is an autosomal recessive disorder.
2. 2. The nurse is providing genetic counseling for an expectant couple who
already have a child with trisomy 18. The nurse should:
a. tell the couple they need to have an abortion within 2 to 3 weeks.
b. explain that the fetus has a 50% chance of having the disorder.
c. discuss options with the couple, including amniocentesis to determine
whether the fetus is affected.
d. refer the couple to a psychologist for emotional support.: ANS: C
Genetic testing, including amniocentesis, would need to be performed to determine
whether the fetus is affected. The couple should be given information about the
likelihood of having another baby with this disorder so that they can make an
informed decision. A genetic counselor is the best source for determining genetic
probability ratios. The couple eventually may need emotional support, but the status
of the pregnancy must be determined first.
3. 3. The nurse is assessing the knowledge of new parents with a child born
with maple syrup urine disease (MSUD). This is an autosomal recessive
inherited disorder, which means that:
a. both genes of a pair must be abnormal for the disorder to be expressed.
, Chapter 06: Genetics, Conception, and Fetal Development
Perry: Maternal Child Nursing Care, 6th Edition
b. only one copy of the abnormal gene is required for the disorder to be
expressed.
c. the disorder occurs in males and heterozygous females.
d. the disorder is carried on the X chromosome.: ANS: A
MSUD is a type of autosomal recessive inheritance disorder in which both genes of
a pair must be abnormal for the disorder to be expressed. MSUD is not an X-linked
dominant or recessive disorder or an autosomal dominant inheritance disorder.
4. 4. In presenting to obstetric nurses interested in genetics, the genetic nurse
identifies the primary risk(s) associated with genetic testing as: a. anxiety and
altered family relationships.
b. denial of insurance benefits.
c. high false-positive results associated with genetic testing.
d. ethnic and socioeconomic disparity associated with genetic testing.: ANS:
B
Decisions about genetic testing are shaped by socioeconomic status and the
ability to pay for the testing. Some types of genetic testing are expensive and are
not covered by insurance benefits. Anxiety and altered family relationships, high
false-positive results, and ethnic and socioeconomic disparity are factors that may
be difficulties associated with genetic testing, but they are not risks associated
with testing.
5. 5. A man's wife is pregnant for the third time. One child was born with cystic
fibrosis, and the other child is healthy. The man wonders what the chance is
that this child will have cystic fibrosis. This type of testing is known as: a.
occurrence risk.
b. recurrence risk.
c. predictive testing.
d. predisposition testing.: ANS: B
The couple already has a child with a genetic disease so they will be given a
recurrence risk test. If a couple has not yet had children but are known to be at risk
for having children with a genetic disease, they are given an occurrence risk test.
Predictive testing is used to clarify the genetic status of an asymptomatic family
member. Predisposition testing differs from presymptomatic testing in that a positive
result does not indicate 100% risk of a condition developing.
6. 6. A key finding from the Human Genome Project is:
a. approximately 20,500 genes make up the genome.
b. all human beings are 80.99% identical at the DNA level.
