Genetics of GI Diseases

Question 1

What is the function of gatekeeper genes?

Answer 1

Regulate cell growth and differentiation

Question 2

Tyrosine kinase inhibitors are ineffective in treating this sub-type of GIST.

Answer 2

Succinate dehydrogenase deficient GIST

Question 3

The MSH2 and MLH1 genes are most commonly mutated in Lynch Syndrome. What is their function?

Answer 3

Function in DNA mismatch repair. Mutation causes microsatellite instability (risk of hairpin loops, deletions, and additions)

Question 4

What is the most common type of mutation causing cancers?

Answer 4

Sporadic mutations

Question 5

How do landscaper genes contribute to cancer development?

Answer 5

Cause abnormal extracellular or intracellular environments that promote cancer development

Question 6

What colon cancer syndrome is associated with the highest lifetime risk of developing colon cancer?

Answer 6

Familial adenomatous polyposis

Question 7

True/False. Somatic cell gene mutations are passed on through generations of people.

Answer 7

False. Somatic mutations are passed through generations of cells, but not generations of people.

Question 8

Intestinal-type gastric carcinoma is most associated with what cause?

Answer 8

H. pylori infection

Question 9

Diffuse gastric carcinoma is generally hereditary. What gene is mutated?

Answer 9

Mutation of CDH1 gene that encodes E-cadherin leading to increased gene transcription

Question 10

This type of cancer seems to have increased frequency within families, but is multifactorial with no single known cause.

Answer 10

Familial cancer

Question 11

True/False. Epigenetic changes that cause cancer are passed through generations of people.

Answer 11

False - epigenetic changes are mitotically passed, but generally do not pass between generations of people. This is because all epigenetic signals are removed during gametogenesis

Question 12

This disorder is caused by hypermethylation of promoter genes for the succinate dehydrogenase.

Answer 12

Carney’s Triad

Question 13

What is the most common inheritance pattern of hereditary cancers?

Answer 13

Autosomal dominant

Question 14

What tyrosine receptor kinase genes are most commonly mutated in GISTs?

Answer 14

KIT, PDGF Receptor A

Question 15

True/False. Hereditary cancer may exhibit incomplete penetrance.

Answer 15

True - this is because of the two-hit hypothesis

Question 16

This type of cancer is associated with a specific gene mutation in germline cells.

Answer 16

Hereditary cancer

Question 17

MutYH-Associated Polyposis (MAPs) is caused by a mutation in the MutYH protein. What is the function of this protein?

Answer 17

Functions in DNA base excision repair to prevent G:C –> T:A transversion mutations

Question 18

What is the cause of familial adenomatous polyposis?

Answer 18

Autosomal dominant germline mutation of the APC gene causing abnormal activation of the Wnt/B-catenin pathway

Question 19

What is the function of caretaker genes?

Answer 19

Maintain genetic stability

Question 20

These cancers are generally driven by a mutation in the tyrosine receptor kinase.

Answer 20

Gastrointestinal Stromal Tumors (GISTs)

Question 21

What is the only colon cancer with autosomal recessive inheritance?

Answer 21

MutYH-Associated Polyposis (MAPs)