Medical Genetics Test Bank Chapter 11 (Cancer Genetics)

1- A LOD score of zero for a recombination frequency of 0.1 indicates??

A) There is no recombination between the disease locus and a marker locus

B) Linkage and non-linkage are equally likely

C) Non-likage is more likely than linkage

D) Linkage is more likely than non-linkage, but only slightly

E) There is loose linkage between the marker and the disease locus

... Answer is B)

2- In a pair of monozygotic twins, one has developed three retinoblastomas during childhood, while the other has developed none. What is the most likely explanation for this??

A) locus heterogeneity

B) Allelic heterogeneity

C) A new mutation has occurred in the unaffected twin, reversing the phenotype

D) Variable expression of the phenotype

E) Incomplete penetrance

... Answer is E)

3- The exon trapping technique is used??

A) to identify coding sequence within a DNA sequence

B) to provide new primers for a PCR reaction

C) to identify promoter regions of genes

D) to test for cross-species conservation of DNA sequence

E) to provide probes for Northern blot analysis

... Answer is A)

4- A 32-bp deletion in the CCR5 gene (also known as CMKBR5) confers almost complete immunity to HIV infection. This gene encodes??

A) a protease that inhibits HIV replication

B) a cytokine receptor that HIV uses to enter T cells

C) a lipoprotein receptor that HIV uses to exit infected T cells

D) an immunoglobulin variant that has high affinity for HIV when the deletion is present

E) A T cell receptor that has high affinity for HIV antigen when the deletion is present

... Answer is B)

5- Members of the PAX gene family encode?

A) growth factor receptors

B) growth factors involved in embryonic development

C) signal transduction molecules important in embryonic development

D) enhancers that upregulate developmental genes

E) transcription factors

... Answer is E)

6- Which of the following is not true of HOX genes??

A) They exist in four major clusters on four different chromosomes in humans.

B) A mutation in one of them causes synpolydactyly

C) They contain a DNA sequence that encodes a DNA-binding homeodomain.

D) These genes are found only in humans, apes, and monkeys

E) They are important in formation of the anterior/posterior axis in the embryo

... Answer is D)

7- Which of the following is not true of spina bifida??

A) It is usually accompanied by secondary hydrocephalus.

B) it can be diagnosed by PCR analysis of fetal cells taken from amniotic fluid.

C) it is considered to be a multifactorial disease

D) At least half of spina bifida cases can be prevented by dietary folic acid supplementation.

E) like anencephaly, it results from a defect in neural tube closure.

... Answer is B)

8- The gene that causes adenomatous polyposis coli, an autosomal dominant form of colon cancer, is an example of?

A) a tumor suppressor gene

B) an oncogene

C) a proto-oncogene

D) a DNA repair gene

E) a gene that affects telomere shortening in dividing cells

... Answer is A)

9- Which of the following would be most likely to produce a pedigree in which there is only one affected individual with no previous family history of the genetic disorder??

A) Autosomal dominant disease with 80% penetrance

B) Autosomal recessive disease

C) Germline mosaicism for an autosomal dominant disease

D) New mutation for an autosomal dominant disease

E) X-linked recessive disease

... Answer is D)

10- Match the type of disease with the most appropriate type of gene therapy: *Autosomal recessive enzyme deficiency that affects nondividing cells?

A) Antisense therapy

B) Retroviral gene replacement therapy

C) Germline therapy

D) Adenoviral gene replacement therapy

E) Germline enhancement therapy

... Answer is D)

11- Match the type of disease with the most appropriate type of gene therapy: *Autosomal resessive enzyme deficiency that affects actively dividing cells?

A) Antisense therapy

B) Retroviral gene replacement therapy

C) Germline therapy

D) Adenoviral gene replacement therapy

E) Germline enhancement therapy

... Answer is B)

12- Match the type of disease with the most appropriate type of gene therapy: *Gain-of-function mutation?

A) Antisense therapy

B) Retroviral gene replacement therapy

C) Germline therapy

D) Adenoviral gene replacement therapy

E) Germline enhancement therapy

... Answer is A)

13- Which of the following characterize trisomy 21, trisomy 18, and trisomy 13??

A) Increase risk with advanced maternal age

B) Hypotonia(decreased muscle tone)

C) Mental retardation

D) Increased risk with advanced paternal age

E) a and c

... Answer is E)

14- Which of the follwing types of cancers is (are) known to contain a highly heritable subset of cases characterized by relatively early age of onset??

A) breast cancer

B) lung cancer

C) colon cancer

D) bladder cancer

E) a and c

... Answer is E)

15- Examples of current gene therapy protocols include?

A) Adenovirus therapy for cystic fibrosis

B) Insertion of vascular endothelial growth factor (VEGF) genew into heart muscle to induce blood vessel formation

C) retrovirus therapy for adenosine deaminase (ADA) deficiency

D) Lung cancer treatment by insertion of normal p53 genes into tumor cells

E) All of the above

... Answer is E)

16- Oncogene Mutations?

A) can affect genes encoding growth factors, growth factor receptors, and signal transduction molecules

B) are usually dominant at the cellular level

C) often produce a gain of function

D) are seen in retinoblastoma and autosomal dominant breast cancer

E) a, b, and c

... Answer is E)

17- T-cell receptor genes?

A) Undergo somatic hypermutation to generate diversity

B) undergo somatic recombination to generate diversity

C) encode molecules that mature to become antibodies

D) exist in multiple copies and are members of a gene family

E) b and d

... Answer is E)

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