Question 1

Which of the following best describes the 'two-hit hypothesis' in the context of tumor suppressor genes?

Accepted Answer

Both alleles of a tumor suppressor gene must be inactivated for cancer to develop.

Question 2

A patient is diagnosed with hereditary non-polyposis colorectal cancer (Lynch syndrome). Which type of genomic instability is most likely present in their tumor cells?

Accepted Answer

Microsatellite instability (MSI)

Question 3

Which of the following is NOT a characteristic of malignant tumor cells?

Accepted Answer

Sensitivity to anti-growth signals

Question 4

A mutation in the MLH1 gene leads to failure in which cellular process?

Accepted Answer

DNA mismatch repair

Question 5

Which of the following best explains why telomerase activation is commonly observed in cancer cells?

Accepted Answer

It allows cells to maintain telomere length and divide indefinitely.

Question 6

A patient with a germline mutation in the RB1 gene develops retinoblastoma. According to Knudson’s two-hit hypothesis, what is the most likely genetic event leading to tumor formation?

Accepted Answer

Loss of heterozygosity (LOH) at the RB1 locus in a retinal cell

Question 7

Which of the following is a common mechanism by which proto-oncogenes become oncogenes?

Accepted Answer

Gain-of-function mutation

Question 8

A tumor sample shows multiple copies of the HER2 gene. Which type of genetic alteration does this represent?

Accepted Answer

Gene amplification

Question 9

Which of the following best describes the role of cell cycle checkpoints in preventing cancer?

Accepted Answer

They halt cell division in response to DNA damage, allowing repair or triggering apoptosis.

Question 10

A patient with familial adenomatous polyposis (FAP) has a germline mutation in the APC gene. Which of the following best explains the increased cancer risk in this patient?

Accepted Answer

Loss of a tumor suppressor gene increases genomic instability, predisposing to additional mutations.

Question 11

Which of the following equations correctly represents the probability ($$P) $$that both alleles of a tumor suppressor gene are inactivated in a cell, assuming the mutation rate per allele is $$\mu$$ and the events are independent?

Accepted Answer

$$P = \mu^2$

Question 12

A patient’s tumor is found to have a translocation between chromosomes 9 and 22, resulting in the BCR-ABL fusion gene. Which type of cancer is most commonly associated with this genetic abnormality?

Accepted Answer

Chronic myeloid leukemia (CML)

Question 13

Which of the following best describes the effect of hypermethylation of CpG islands in the promoter region of a tumor suppressor gene?

Accepted Answer

Gene silencing, leading to loss of tumor suppressor function

Question 14

A patient with a family history of multiple cancers is found to have a germline mutation in the TP53 gene. Which syndrome is most likely present?

Accepted Answer

Li-Fraumeni syndrome

Question 15

Which of the following is a direct consequence of chromosomal instability (CIN) in cancer cells?

Accepted Answer

Aneuploidy and structural chromosome abnormalities

Question 16

A patient’s tumor is found to have a point mutation in the KRAS gene. Which of the following cancers is most likely associated with this mutation?

Accepted Answer

Pancreatic cancer

Question 17

Which of the following best explains why loss-of-function mutations in mismatch repair (MMR) genes lead to increased cancer risk?

Accepted Answer

They allow accumulation of replication errors, increasing genomic instability.

Question 18

A new targeted therapy is developed to inhibit the activity of a constitutively active tyrosine kinase caused by a gene fusion. Which of the following best describes the rationale for this therapy?

Accepted Answer

Blocking the driver mutation can halt tumor growth and progression.

Question 19

Which of the following is a real-world example of a cancer therapy that targets a specific driver gene mutation?

Accepted Answer

Trastuzumab (Herceptin) for HER2-amplified breast cancer

Question 20

A tumor is found to have both loss of function in a tumor suppressor gene and gain of function in an oncogene. Which of the following best describes the combined effect on the cell?

Accepted Answer

Uncontrolled proliferation due to loss of growth inhibition and increased growth signaling

Cancer Genetics: Mechanisms, Mutations, and Clinical Implications

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