Block 7 Michigan Genetic - Pt 2

14 Questions | By Rossstudent | Updated: Mar 21, 2022 | Attempts: 226

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1.

Sickle cell anemia is:
- A.
  
  An autosomal dominant disease.
- B.
  
  Always caused by the same point mutation in the beta-globin gene.
- C.
  
  Rarely due to the same mutation in unrelated individuals.
- D.
  
  Caused by mutations in either the alpha-globin gene or the beta-globin gene
- E.
  
  An X-linked recessive disease
2.

The pedigree below is from a family with cystic fibrosis, an autosomal recessive condition. What is the best estimate that individual I-3 is a carrier of cystic fibrosis?
- A.
  
  1/4
- B.
  
  1/3
- C.
  
  1/2
- D.
  
  2/3
- E.
  
  3/4
3.

Which of the following observations is the strongest evidence for an important genetic component in the causation of type-1 diabetes mellitus (IDDM)?
- A.
  
  Pancreatic B-cell autoantibodies are frequently present
- B.
  
  Approximately 10% of affected individuals have an affected sibling.
- C.
  
  Onset of disease is usually in childhood
- D.
  
  The concordance rate in monozygotic twins is approximately 30%.
- E.
  
  The concordance rate in monozygotic twins is five times that in dizygotic twins.
4.

The average recurrence risk for a couple that has had a child with cleft lip, a multifactorial birth defect, is approximately 4%. What is the recurrence risk if the couple has two affected children?
- A.
  
  2%
- B.
  
  4%
- C.
  
  10%
- D.
  
  25%
- E.
  
  50%
5.

Ankylosing spondylitis is a chronic inflammatory arthritis affecting the spine and sacroiliac joints. 95% of Caucasian patients are positive for the HLA-B27 haplotype; whereas, 7% of all Caucasians are positive. This is evidence for:
- A.
  
  Association of ankylosing spondylitis with the B27 allele of the HLA-B locus.
- B.
  
  Linkage of ankylosing spondylitis to the HLA-B locus.
- C.
  
  Neither.
6.

Which karyotype would be MOST frequently seen in liveborn infants (as opposed to spontaneous abortions)?
- A.
  
  47,XX,+21
- B.
  
  47,XX,+3
- C.
  
  69,XXX
- D.
  
  46,XY,-11,+22
- E.
  
  46,YY
7.

The family below is segregating a very rare autosomal recessive disease with 100% penetrance. The disease is present and recognizable at birth and does not decrease fitness. Assume no locus heterogeneity. What is the chance that the fetus (IV-1) is affected with this disease?
- A.
  
  1/4
- B.
  
  1/2
- C.
  
  1/9
- D.
  
  2/9
- E.
  
  4/9
8.

The G8 RFLP marker is closely linked to the Huntington disease (HD) locus, and it is useful for linkage analysis in HD families. True or False: The base changes responsible for the G8 polymorphism are also responsible for HD
- A.
  
  True
- B.
  
  False
9.

Assuming Hardy-Weinberg equilibrium for alleles at the CFTR (cystic fibrosis) locus in the U.S. Caucasian population, and given that the mutant allele frequency, q, is 1/50, what fraction of this population are carriers of a CFTR mutation?
- A.
  
  (49/50)2
- B.
  
  (1/50)2
- C.
  
  1/100
- D.
  
  1/50
- E.
  
  2/50
10.

The proband, III-1, has cystic fibrosis (CF). DNA analysis indicates that III-1 is homozygous for a particular CF mutant, but his grandmother (I-2) is homozygous normal. Assume that q=1/50 for this mutant allele, and that the population is in Hardy-Weinberg equilibrium. What is the chance of I-1 being a carrier of CF?
- A.
  
  100%
- B.
  
  50%
- C.
  
  4%
- D.
  
  2%
- E.
  
  0.5%
11.

The proband, III-1, has cystic fibrosis (CF). DNA analysis indicates that III-1 is homozygous for a particular CF mutant, but his grandmother (I-2) is homozygous normal. Assume that q=1/50 for this mutant allele, and that the population is in Hardy-Weinberg equilibrium. What is the chance of II-5 being a carrier?
- A.
  
  100%
- B.
  
  50%
- C.
  
  4%
- D.
  
  2%
- E.
  
  0.5%
12.

The proband, III-1, has cystic fibrosis (CF). DNA analysis indicates that III-1 is homozygous for a particular CF mutant, but his grandmother (I-2) is homozygous normal. Assume that q=1/50 for this mutant allele, and that the population is in Hardy-Weinberg equilibrium. What is the chance of III-2 being affected with CF
- A.
  
  100%
- B.
  
  50%
- C.
  
  4%
- D.
  
  2%
- E.
  
  0.5%
13.

Prader-Willi syndrome (PWS) can result from either an interstitial deletion involving the paternal copy of chromosome subregion 15q1-q13 or from maternal uniparental disomy of chromosome 15. The reason for this is:
- A.
  
  The maternal copy of the gene(s) responsible for Angelman syndrome (AS) is imprinted and is not expressed.
- B.
  
  PWS results from an anomaly of X-chromosome inactivation
- C.
  
  The paternal copy of the gene(s) responsible for PWS is imprinted and is not expressed.
- D.
  
  The maternal copy of the gene(s) responsible for PWS is imprinted and is not expressed
- E.
  
  The maternal copy of the gene(s) responsible for PWS exerts a dominant negative effect of the paternal allele
14.

Familial retinoblastoma (FRB) is an autosomal dominant cancer predisposition syndrome, due to a defect in the RB tumor suppressor gene. An affected individual typically inherits a single defective copy from one parent, and a normal copy from the other parent. Below are Southern blots for an individual with FRB; both normal and tumor cells were typed for three RFLP markers flanking the RB locus on chromosome 13 (N = normal cells, T = tumor cells). Based upon these data, which of the following is the most likely explanation for the loss of heterozygosity in this individual?
- A.
  
  Mitotic crossover
- B.
  
  Loss of the normal chromosome 13
- C.
  
  Independent second mutation
- D.
  
  Loss of the normal chromosome 13 and reduplication of the mutant chromosome 13