Genetic predisposition to cancer Flashcards
What are oncogenes
Mutated protoncogenes
What do oncogenes cause
Accelerated cell division
What is the result of tumour to tumour suppression genes
1st mutation- susceptable carrier accelerated cell division
2nd mutation- leads to cancer
What are the Cancer associated with BRCA-1
Breast cancer -50-85%
Second primary breast cancer - 40-60%
Ovarian cancer 15%-45%
Name the 2 types of gene mutations in which cancer arises from?
Somatic and Germline mutations
Name the 3 types of genes associated with Cancer?
Oncogenes
Tumour suppressor genes
DNA damage-response genes
Location for somatic and germline mutation
Somatic occurs in nongermline tissue and are nonheritable
Germlinic mutations are present in egg or sperm and are heritable
Explain the difference between Benign, malignant, Dysplastic
Benign - lack ability to metastasize, rarely or never become cancerous but can still cause health effects due to pressure on other organs
Dysplastic - ‘benign’ but could progress to malignancy, cells show abnormalities of appearance and cell maturation
Malignant - Able to metastasize
How does HNPCC (Hereditary non-polyposis coloerectal cancer) occur?
Failure of Mismatch repair genes
Nature of oncogene in cancers
It is the dominant gene in effect
Nature of the TSG (Tumour Suppressor Gene)
Recessive genes in effect
Risk factors of breast cancer (5)
Ageing
Family history
Dietary factors
Lack of exercise
Late menopause
Role of mismatch repair (MMR) and where
Corrects errors that occur during DNA replication like single base mismatches or short insertions and deletions
TSG normal effect, 1st mutation and 2nd mutation
Normal genes prevent cancer
1st mutation gene acts as a susceptible carrier
2nd mutation leads to cancer
What can mutation in proto-oncogene result in
Gene transforming into an oncogene which accelerates cell division
What does failure of mismatch repair (MMR) lead to and what are they
Microsatelite instability (MSI)
These are regions of repeated DNA that change in length
It is the phenotypic evidence that MMR isn’t working
What is Retinoblastoma disease and how can it occur
Most common eye tumour in children
Occurs in heritable and nonheritable forms
When does cancer occur in relation to TSG and results of this
When both genes fail (2 hit hypothesis) which speeds the accumulation of mutations in critical genes
Where do De Novo mutations take place
Takes place in a germ cell of a parent, the new individual has the new alterations in all of their germ line but isn’t present in the parent
2 forms of Hereditary coloerectal cancer syndromes
Non polyposis where there is few to no adenomas
Polyposis where there is multiple adenomas
