Genetic Predisposition to Cancer Flashcards
Mutations cause faulty proteins, what are the possibilities?
- Functional protein
- Non-functional or missing protein
- Protein with reduced function
What does cancer arise from?
Gene mutations
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Describe the cell cycle?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/367/264/718/q_image_thumb.png?1603356204)
What are oncogenes?
Oncogenes = regulate cell growth
- A mutation of oncogenes leads to accelerated cell division, and ultimately maybe cancer
What are tumour suppresor genes?
Tumour suppressor genes = normal genes that slow down cell division, repair DNA mistakes or tell cells when to die
- 1st mutation makes you susceptible to cancer
- 2nd mutation leads to cancer
Describe the pathogenesis of cancer, using colon cancer as an example?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/367/264/722/a_image_thumb.png?1603356252)
What is the main mechanism for familial cancer?
Faulty DNA mismatch repair
![](https://s3.amazonaws.com/brainscape-prod/system/cm/367/264/723/a_image_thumb.png?1603356280)
Is familial cancer autosomal dominant or recessive?
Is autosomal dominant inheritance:
- Each child has 50% chance of inheriting mutation
- No skipped generations
- Equally transmitted by men and woman
![](https://s3.amazonaws.com/brainscape-prod/system/cm/367/264/724/a_image_thumb.png?1603356308)
What is Lynch syndrome/HNPCC?
Is a mutation in mismatch repair genes:
- Excess of colorectal, endometrial, urinary tract, ovarian and gastric cancer
- Adenoma-carcinoma sequence for polyp formation
What cancers does Lynch syndrome/HNPCC increase risks of?
Excess of colorectal, endometrial, urinary tract, ovarian and gastric cancer
![](https://s3.amazonaws.com/brainscape-prod/system/cm/367/264/726/a_image_thumb.jpg?1603356364)
What are clinical features of lynch syndrome/HNPCC?
- Early but variable age of diagnosis
- Tumour site in proximal colon predominates
What investigations are done for lynch syndrome/HNPCC?
- Genetic testing
- IHC for mismatch repair gene proteins
- Or microsatellite instability testing (MSI)
What is Lynch syndrome also known as?
Hereditary non-polyposis colorectal cancer (HNPCC)
When should you suspect hereditary cancer syndrome?
- Cancer in 2 or more close relatives
- Early age of diagnosis
- Multiple primary tumours
- Bilateral or multiple rare cancers
Describe the cancer genetics process at the clinic?
- Detailed family history
- Verbally reported pedigree and then revised pedigree based on pathology reports
- Confirm diagnosis of cancer
- Risk estimation
- Genetic centres can classify people as gene carrier who is high, medium or low risk (low risk being similar to population average)
- Interventions
- Awareness of symptoms/signs
- Lifestyle – diet, smoking, exercised
- Prevention – oestrogen, aspirin
- Screening
- Prophylactic surgery
- Genetic testing
- Consider in high risk