Neurogenetics
QUESTIONS
1. Which one of the following is associated with a trinucleotide repeat expansion?
A. Tuberous sclerosis
B. McCardle’s disease
C. Myotonic dystrophy
D. Sjögren’s syndrome
E. Acute intermittent porphyria
View Answer
1. Answer: C. Myotonic dystrophy is associated with a CTG repeat expansion. None of the others are triple repeat disorders.
2. You examine a child with weakness, wasting of the calf muscles, and diminished ankle reflexes. On nerve conduction study, you find severe slowing of the conduction velocity. Several of the patient’s relatives have had similar symptoms, including the patient’s father as well as three of her four siblings. This disease is most likely is associated with which chromosome?
A. 1
B. 12
C. 6
D. 21
E. X linked
View Answer
2. Answer: D. Charcot-Marie-Tooth (CMT) disease type 2C is a primarily axonal sensorimotor polyneuropathy. CMT type 2C is autosomal dominant and is associated with chromosome 12.
3. A variant of the apolipoprotein E (apoE) gene has been linked with increased risk of Alzheimer’s disease. On which chromosome is this gene found?
A. 1
B. X
C. 19
D. 23
E. 6
View Answer
3. Answer: C. The apoE gene is located on chromosome 19.
4. A patient is diagnosed with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke (MELAS), which is a mitochondrial genetic disorder. Which of the following medications should be avoided?
A. Warfarin
B. Valproic acid
C. Aspirin
D. Gabapentin
E. Leviteracitam
View Answer
4. Answer: B. Valproic acid has been shown to exacerbate symptoms of MELAS. Patients with MELAS typically have ischemic strokes, migraine headaches, hearing loss, growth retardation, and limb weakness/exercise intolerance.
5. A patient is diagnosed with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Which of the following is true?
A. Pseudobulbar palsy is a rare complication.
B. Mutation of the Notch3 gene
C. Skin biopsy is diagnostic.
D. Strokes are rare complications.
E. None of the above
View Answer
5. Answer: B. Mutation of the Notch3 gene is associated with CADASIL. Recurrent strokes, migraines, depression, pseudobulbar palsy, and subcortical dementia are all associated with this disease. Skin biopsy can be helpful but is not diagnostic.
6. The triad of dysmorphic features, periodic paralysis, and cardiac arrhythmias is part of Anderson-Tawil syndrome. This syndrome is associated with what mutation?
A. Sodium channel gene
B. Potassium channel gene
C. Dopamine synthesis gene
D. Triple repeat disorder
E. X-linked recessive
View Answer
6. Answer: B. Anderson-Tawil syndrome is associated with potassium channel mutation. In theory, the gene controls the inward rectifying potassium channel; therefore, mutations are supposed to cause hypokalemia, however, this has not been confirmed.
7. The majority of inborn errors of metabolism are inherited in what fashion?
A. X-linked recessive
B. Autosomal dominant
C. Sporadic
D. Autosomal recessive
E. None of the above
View Answer
7. Answer: D. Most inborn errors of metabolism are inherited as autosomal recessive conditions.
8. Neurofibromatosis type 2 (NF2) is associated with meningiomas and acoustic neuromas (often bilateral). NF1 has better prognosis and is associated with a lower incidence of central nervous system (CNS) tumors. The NF1 gene codes for neurofibromin. What is the function of this protein?
A. ATPase associated
B. Tumor suppressor
C. Pro-oncogene
D. cAMP associated
E. None of the above
View Answer
8. Answer: B. Mutation or deletion of the NF gene results in neurofibromatosis. The gene product is neurofibromin, which acts as a tumor suppressor; therefore, a decrease in production or absent levels results in the clinical features.
9. NF1 is inherited in what fashion and is associated with which chromosome?
A. AR: 15
B. AD: 17
C. AD: 22
D. X-linked
E. AR: 9
View Answer
9. Answer: B. NF1 is an autosomal dominant condition, and only one gene needs to be deleted or mutated to result in the condition. The NF1 gene has been localized to chromosome 17.
10. Duchenne’s muscular dystrophy (DMD) is the most common type of muscular dystrophy. Which statement is true?
A. Spontaneous transmission is the most common.
B. Autosomal dominant transmission is the most common.
C. X-linked transmission is the most common.
D. The size of the mutation increases the severity of the disease.
E. Missense mutation is the most common cause of DMD.
View Answer
10. Answer: C. DMD is most commonly transmitted in an X-linked fashion. Larger deletions of one or more exons account for most of the causes of DMD (not missense mutations). The size of the mutation does not determine the severity of disease.
11. Which of the following is the most common hereditary ataxia syndrome?
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