Complex (non-mendelian) inheritance Flashcards
What is penetrance?
Extent to which particular gene is expressed in phenotypes of individuals carrying it
What is incomplete penetrance?
Not every individual with gene expresses trait
Define precision/personalised medicine?
Checking DNA mutations could be used to tell risk of developing disease (e.g. breast cancer)
Based on penetrance in other people with same genes
What are genetic modifiers in terms of penetrance?
Genes with small effect on expression of another gene
What else effects penetrance?
Environmental factors:
Lifestyle
Air pollution
Alcohol
Diet etc.
What is an imprinted gene?
Silenced or deactivated
How does genomic imprinting effect inheritance?
Epigenetic (behaviour/environment change how genes work)
If gene from one parent is imprinted, only gene from other is expressed = mono-allelic child
Why do imprinted genes have a higher risk of mutation?
Only one active allele
More susceptible to mutations
From which parent does mitochondrial DNA come?
Entirely Maternal
Why does mitochondrial DNA have a much higher mutation rate than the nuclear genome?
Lacks efficient DNA repair system
-Lacks protective proteins (histones)
- Damaged by reactive oxygen species (ROS) (Free radicals)
What is Homoplasmy?
MtDNA uniform within cell
What is heteroplasmy?
MtDNA in mitochondria of cell is different (i.e. some are mutated)
What is the effect on disease of mitochondiral inheritance?
More mutated mtDNA = more serious disease
Why is a cell’s mtDNA often polyploidy?
(2+ complete chromosome sets)
Each cell has thousands of mitochondria and 2-10 copies of DNA in each
What does anticipation mean?
Diseases presents younger or more severely in succeeding generations
