Genetics Flashcards
describe somatic mosaicism
two genetically distinct populations fo cells within an individual, derived from post-zygotic mutations
why do most variations in DNA as cells divide not matter
only around 2% of the genome is coding
what does inactivation of a tumour suppressor cause?
inability to control cell growth
how does inactivation of a tumour suppressor happen
Knudson’s two hit hypothesis
most common form of cancer inheritance
multifactorial
role of oncogenes
stimulate cell growth
how can an oncogene be activated?
- duplication
- activation of promoter
- change in amino acid sequence
driver mutations
determines cancer characteristics
NGS
identify mutations and give genomic profile of cancer
SNPs
show alterations in DNA sequence
passenger
incidental mutations that happen because the genome is unstable
what does a Philadelphia chromosome do?
switch oncogene on
what inhibits the Philadelphia chromosome switching an oncogene on?
imatinib
cancer risk
function of the genotype and environment
cancer behaviour
function of somatic mutations
cancer risk statistics
population
multifactorial (3%)
mutation (8%)
how can high penetrance risk be modified?
screening early
hormonal manipulation
surgical intervention
grade
what the cells look like
stage
how far the cancer has spread
karyotyping
whole genome sequenced to show large abnormalities
FISH
fluorescence certain chromosomes, targeted
MSI
Microsatellite instability
what is microsatellite instability
condition of genetic hypermutability (predisposition to mutation) that results from impaired DNA mismatch repair
