Genetic predispositions to cancer Flashcards
What is the difference between a somatic and germline mutation?
Somatic mutations occur in nongermline tissues and are non-inheritable
Germline mutations are present in egg or sperm, so all cells of the child are affected
What is the difference between an oncogene and a proto-oncogene?
Proto-oncogene are genes that code for proteins to regulate cell growth and differentiation
Mutations cause them to change to oncogenes - disfunctional - accelerate cell division
What is the function of tumour suppressor genes?
Inhibit cell cycle
Promote apoptosis
Describe how failure of DNA damage-response genes can cause cancer
These normally ‘repair’ DNA
When maternal and paternal DNA damage response genes fail, then mutations accumulate in other genes
This can lead to cancer
Microsatellite instability is characterised by…
Addition of nucleotide repeats
Microsatellite instability (MSI) is the condition of genetic hypermutability (predisposition to mutation) that results from impaired DNA mismatch repair
What does dysplastic mean?
Refers to a benign tumour that could progress to malignancy (gain ability to metastasize)
Sometimes referred to as pre-malignant
What are ‘De Novo’ mutations?
Mutation in germ cell of parent
Offspring predisposed to cancer
No family history of hereditary cancer syndromes
‘Most cancer susceptibility genes are dominant, but with incomplete penetrance’
What are the key features to notice when looking at a family history?
Incomplete penetrance - Not everyone has gene
- It may appear to skip generations
Susceptibility
- Offspring with the gene do not necessarily get that cancer
What is stratified medicine?
Identifying subgroups of patients with distinct mechanisms of disease, or responses to treatment
In terms of genetics and cancer, it is finding groups of patients who may be predisposed to cancer
