Genetics of GI Diseases Flashcards
What is the function of gatekeeper genes?
Regulate cell growth and differentiation
Tyrosine kinase inhibitors are ineffective in treating this sub-type of GIST.
Succinate dehydrogenase deficient GIST
The MSH2 and MLH1 genes are most commonly mutated in Lynch Syndrome. What is their function?
Function in DNA mismatch repair. Mutation causes microsatellite instability (risk of hairpin loops, deletions, and additions)
What is the most common type of mutation causing cancers?
Sporadic mutations
How do landscaper genes contribute to cancer development?
Cause abnormal extracellular or intracellular environments that promote cancer development
What colon cancer syndrome is associated with the highest lifetime risk of developing colon cancer?
Familial adenomatous polyposis
True/False. Somatic cell gene mutations are passed on through generations of people.
False. Somatic mutations are passed through generations of cells, but not generations of people.
Intestinal-type gastric carcinoma is most associated with what cause?
H. pylori infection
Diffuse gastric carcinoma is generally hereditary. What gene is mutated?
Mutation of CDH1 gene that encodes E-cadherin leading to increased gene transcription
This type of cancer seems to have increased frequency within families, but is multifactorial with no single known cause.
Familial cancer
True/False. Epigenetic changes that cause cancer are passed through generations of people.
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
This disorder is caused by hypermethylation of promoter genes for the succinate dehydrogenase.
Carney’s Triad
What is the most common inheritance pattern of hereditary cancers?
Autosomal dominant
What tyrosine receptor kinase genes are most commonly mutated in GISTs?
KIT, PDGF Receptor A
True/False. Hereditary cancer may exhibit incomplete penetrance.
True - this is because of the two-hit hypothesis
This type of cancer is associated with a specific gene mutation in germline cells.
Hereditary cancer
MutYH-Associated Polyposis (MAPs) is caused by a mutation in the MutYH protein. What is the function of this protein?
Functions in DNA base excision repair to prevent G:C –> T:A transversion mutations
What is the cause of familial adenomatous polyposis?
Autosomal dominant germline mutation of the APC gene causing abnormal activation of the Wnt/B-catenin pathway
What is the function of caretaker genes?
Maintain genetic stability
These cancers are generally driven by a mutation in the tyrosine receptor kinase.
Gastrointestinal Stromal Tumors (GISTs)
What is the only colon cancer with autosomal recessive inheritance?
MutYH-Associated Polyposis (MAPs)
