2026 AGN-BC Exam Prep: Advanced Genetics
Nursing Practice Questions with Answer
Rationales for Genomics, Genetic Testing, Risk
Assessment, Counseling, Clinical Care, and
Study Guide
Section 1: Genomics & Basic Principles
Question 1:
Which of the following best describes the mode of inheritance in which a single
mutated allele is sufficient to cause disease?
A) Autosomal recessive
B) Autosomal dominant
C) X-linked recessive
D) Mitochondrial
Answer: B
Rationale: Autosomal dominant disorders require only one mutated allele to
cause disease. Examples include Huntington's disease, Marfan syndrome, and
hereditary breast cancer syndromes. Option A requires two mutated alleles.
Option C typically affects males and requires the mutation on the X chromosome.
Option D is inherited exclusively from the mother through mitochondrial DNA.
Question 2:
A couple has a child with cystic fibrosis. Both parents are asymptomatic. What is
the mode of inheritance?
A) Autosomal dominant
B) Autosomal recessive
C) X-linked dominant
D) Mitochondrial
,Answer: B
Rationale: Cystic fibrosis is an autosomal recessive disorder. Both parents are
obligate carriers (heterozygous) and are asymptomatic. Each pregnancy carries a
25% risk of an affected child, 50% risk of a carrier, and 25% risk of an unaffected
non-carrier. Options A, C, and D do not fit the clinical scenario of asymptomatic
carrier parents.
Question 3:
Which of the following disorders demonstrates anticipation?
A) Cystic fibrosis
B) Huntington's disease
C) Down syndrome
D) Sickle cell anemia
Answer: B
Rationale: Anticipation refers to a pattern in which a genetic disorder presents at
an earlier age and with increased severity in successive generations. Huntington's
disease is a classic example due to CAG trinucleotide repeat expansion. Cystic
fibrosis, Down syndrome, and sickle cell anemia do not demonstrate anticipation.
Question 4:
A male child is diagnosed with hemophilia A. His mother has no family history of
bleeding disorders. Which of the following is the most likely explanation?
A) The father is a carrier
B) A de novo mutation occurred in the mother's germline
C) The child inherited the mutation from his father
D) The disorder is autosomal recessive
Answer: B
Rationale: Hemophilia A is an X-linked recessive disorder. Since the mother has
no family history, a de novo mutation in the maternal germline is the most likely
explanation. Option A is incorrect because fathers cannot be carriers of X-linked
disorders in the traditional sense (they either have it or not). Option C is incorrect
,because fathers pass a Y chromosome to sons. Option D is incorrect; hemophilia A
is X-linked.
Question 5:
What is the probability that a carrier couple (both heterozygous) for an autosomal
recessive disorder will have an affected child?
A) 0%
B) 25%
C) 50%
D) 100%
Answer: B
Rationale: For two carriers of an autosomal recessive disorder, each pregnancy
has a 25% chance of an affected child (homozygous), 50% chance of a carrier
(heterozygous), and 25% chance of an unaffected non-carrier. Option A is
incorrect. Option C is the carrier risk. Option D is incorrect.
Question 6:
Which of the following is an example of variable expressivity?
A) A person with a BRCA1 mutation always develops breast cancer
B) Family members with the same NF1 mutation have different severity of
symptoms
C) A disorder that skips generations
D) A disorder that only affects males
Answer: B
Rationale: Variable expressivity refers to the range of severity of a phenotype
among individuals with the same genotype. Neurofibromatosis type 1 (NF1) is a
classic example where family members may have mild to severe manifestations.
Option A describes complete penetrance. Option C describes reduced penetrance
or recessive inheritance. Option D describes X-linked inheritance.
, Question 7:
Which of the following best describes penetrance?
A) The severity of a disease
B) The proportion of individuals with a genotype who express the phenotype
C) The age at which a disease manifests
D) The number of genes involved in a disease
Answer: B
Rationale: Penetrance is the proportion of individuals with a specific genotype
who actually express the associated phenotype. Option A describes expressivity.
Option C describes age of onset. Option D describes polygenic inheritance.
Question 8:
A patient has a mutation in mitochondrial DNA. Which of the following is true
regarding inheritance?
A) It is inherited from the father
B) It is inherited from the mother
C) It follows autosomal dominant inheritance
D) It cannot be inherited
Answer: B
Rationale: Mitochondrial DNA is inherited exclusively from the mother. Fathers
do not contribute mitochondria to the zygote. Options A, C, and D are incorrect.
Question 9:
Which of the following is an example of a trinucleotide repeat disorder?
A) Down syndrome
B) Fragile X syndrome
C) Turner syndrome
D) Klinefelter syndrome
Answer: B
Rationale: Fragile X syndrome is caused by an expansion of CGG trinucleotide
Nursing Practice Questions with Answer
Rationales for Genomics, Genetic Testing, Risk
Assessment, Counseling, Clinical Care, and
Study Guide
Section 1: Genomics & Basic Principles
Question 1:
Which of the following best describes the mode of inheritance in which a single
mutated allele is sufficient to cause disease?
A) Autosomal recessive
B) Autosomal dominant
C) X-linked recessive
D) Mitochondrial
Answer: B
Rationale: Autosomal dominant disorders require only one mutated allele to
cause disease. Examples include Huntington's disease, Marfan syndrome, and
hereditary breast cancer syndromes. Option A requires two mutated alleles.
Option C typically affects males and requires the mutation on the X chromosome.
Option D is inherited exclusively from the mother through mitochondrial DNA.
Question 2:
A couple has a child with cystic fibrosis. Both parents are asymptomatic. What is
the mode of inheritance?
A) Autosomal dominant
B) Autosomal recessive
C) X-linked dominant
D) Mitochondrial
,Answer: B
Rationale: Cystic fibrosis is an autosomal recessive disorder. Both parents are
obligate carriers (heterozygous) and are asymptomatic. Each pregnancy carries a
25% risk of an affected child, 50% risk of a carrier, and 25% risk of an unaffected
non-carrier. Options A, C, and D do not fit the clinical scenario of asymptomatic
carrier parents.
Question 3:
Which of the following disorders demonstrates anticipation?
A) Cystic fibrosis
B) Huntington's disease
C) Down syndrome
D) Sickle cell anemia
Answer: B
Rationale: Anticipation refers to a pattern in which a genetic disorder presents at
an earlier age and with increased severity in successive generations. Huntington's
disease is a classic example due to CAG trinucleotide repeat expansion. Cystic
fibrosis, Down syndrome, and sickle cell anemia do not demonstrate anticipation.
Question 4:
A male child is diagnosed with hemophilia A. His mother has no family history of
bleeding disorders. Which of the following is the most likely explanation?
A) The father is a carrier
B) A de novo mutation occurred in the mother's germline
C) The child inherited the mutation from his father
D) The disorder is autosomal recessive
Answer: B
Rationale: Hemophilia A is an X-linked recessive disorder. Since the mother has
no family history, a de novo mutation in the maternal germline is the most likely
explanation. Option A is incorrect because fathers cannot be carriers of X-linked
disorders in the traditional sense (they either have it or not). Option C is incorrect
,because fathers pass a Y chromosome to sons. Option D is incorrect; hemophilia A
is X-linked.
Question 5:
What is the probability that a carrier couple (both heterozygous) for an autosomal
recessive disorder will have an affected child?
A) 0%
B) 25%
C) 50%
D) 100%
Answer: B
Rationale: For two carriers of an autosomal recessive disorder, each pregnancy
has a 25% chance of an affected child (homozygous), 50% chance of a carrier
(heterozygous), and 25% chance of an unaffected non-carrier. Option A is
incorrect. Option C is the carrier risk. Option D is incorrect.
Question 6:
Which of the following is an example of variable expressivity?
A) A person with a BRCA1 mutation always develops breast cancer
B) Family members with the same NF1 mutation have different severity of
symptoms
C) A disorder that skips generations
D) A disorder that only affects males
Answer: B
Rationale: Variable expressivity refers to the range of severity of a phenotype
among individuals with the same genotype. Neurofibromatosis type 1 (NF1) is a
classic example where family members may have mild to severe manifestations.
Option A describes complete penetrance. Option C describes reduced penetrance
or recessive inheritance. Option D describes X-linked inheritance.
, Question 7:
Which of the following best describes penetrance?
A) The severity of a disease
B) The proportion of individuals with a genotype who express the phenotype
C) The age at which a disease manifests
D) The number of genes involved in a disease
Answer: B
Rationale: Penetrance is the proportion of individuals with a specific genotype
who actually express the associated phenotype. Option A describes expressivity.
Option C describes age of onset. Option D describes polygenic inheritance.
Question 8:
A patient has a mutation in mitochondrial DNA. Which of the following is true
regarding inheritance?
A) It is inherited from the father
B) It is inherited from the mother
C) It follows autosomal dominant inheritance
D) It cannot be inherited
Answer: B
Rationale: Mitochondrial DNA is inherited exclusively from the mother. Fathers
do not contribute mitochondria to the zygote. Options A, C, and D are incorrect.
Question 9:
Which of the following is an example of a trinucleotide repeat disorder?
A) Down syndrome
B) Fragile X syndrome
C) Turner syndrome
D) Klinefelter syndrome
Answer: B
Rationale: Fragile X syndrome is caused by an expansion of CGG trinucleotide
