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NF1 FINAL EXAM
Question 1
NF1 is caused by a mutation in which gene?
A) NF2
B) TP53
C) NF1
D) BRCA1
Answer: C
Rationale: NF1 is caused by mutations in the NF1 gene on
chromosome 17q11.2, which encodes neurofibromin.
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Question 2
The inheritance pattern of NF1 is:
A) Autosomal recessive
B) X-linked dominant
C) Autosomal dominant
D) Mitochondrial
Answer: C
Rationale: NF1 follows autosomal dominant inheritance with
complete penetrance but variable expressivity.
Question 3
Approximately what percentage of NF1 cases are de novo
mutations?
A) 10%
B) 30%
C) 50%
D) 80%
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Answer: C
Rationale: About 50% of NF1 cases result from new mutations,
with a known paternal age effect.
Question 4
Neurofibromin primarily functions as a:
A) Kinase activator
B) Ras GTPase-activating protein (GAP)
C) Transcription factor
D) Cell adhesion molecule
Answer: B
Rationale: Neurofibromin accelerates hydrolysis of Ras-GTP to
Ras-GDP, downregulating the Ras/MAPK signaling pathway.
Question 5
Loss of heterozygosity (LOH) in NF1 contributes to:
A) Complete symptom resolution
, Page 4 of 191
B) Tumor formation
C) Increased neurofibromin production
D) Reduced mutation rate
Answer: B
Rationale: LOH inactivates the second NF1 allele, leading to
tumorigenesis (Knudson’s two-hit hypothesis).
Question 6
The NF1 gene spans approximately:
A) 100 kb
B) 350 kb
C) 150 kb
D) 500 kb
Answer: B
Rationale: The NF1 gene is large (~350 kb) with 57
constitutive exons and alternative splicing variants.
NF1 FINAL EXAM
Question 1
NF1 is caused by a mutation in which gene?
A) NF2
B) TP53
C) NF1
D) BRCA1
Answer: C
Rationale: NF1 is caused by mutations in the NF1 gene on
chromosome 17q11.2, which encodes neurofibromin.
,Page 2 of 191
Question 2
The inheritance pattern of NF1 is:
A) Autosomal recessive
B) X-linked dominant
C) Autosomal dominant
D) Mitochondrial
Answer: C
Rationale: NF1 follows autosomal dominant inheritance with
complete penetrance but variable expressivity.
Question 3
Approximately what percentage of NF1 cases are de novo
mutations?
A) 10%
B) 30%
C) 50%
D) 80%
,Page 3 of 191
Answer: C
Rationale: About 50% of NF1 cases result from new mutations,
with a known paternal age effect.
Question 4
Neurofibromin primarily functions as a:
A) Kinase activator
B) Ras GTPase-activating protein (GAP)
C) Transcription factor
D) Cell adhesion molecule
Answer: B
Rationale: Neurofibromin accelerates hydrolysis of Ras-GTP to
Ras-GDP, downregulating the Ras/MAPK signaling pathway.
Question 5
Loss of heterozygosity (LOH) in NF1 contributes to:
A) Complete symptom resolution
, Page 4 of 191
B) Tumor formation
C) Increased neurofibromin production
D) Reduced mutation rate
Answer: B
Rationale: LOH inactivates the second NF1 allele, leading to
tumorigenesis (Knudson’s two-hit hypothesis).
Question 6
The NF1 gene spans approximately:
A) 100 kb
B) 350 kb
C) 150 kb
D) 500 kb
Answer: B
Rationale: The NF1 gene is large (~350 kb) with 57
constitutive exons and alternative splicing variants.
