Natural Gene Variation Flashcards
How much of our DNA do we share with others?
99.9%
What are natural variations in our DNA known as?
Single Nucleotide Polymorphisms
How many SNPs have been identified?
3,300,000
What are gene association studies?
A targeted approach - look for sorting of SNP’s in genes
What is the difference between a functional SNP and a genetic tag?
Functional - changes amino acid, has an effect
Genetic tags - silent, no effect on which is expressed. Associated with a disorder, not the SNIP itself but something surrounding it causes change in DNA
What are genome wide association studies?
Look for what SNPs sort with disease state - if genes come up, can look at them
What is a polygenetic trait?
Inheriting loads of variants - increases the likelihood
What happens in alzeimers?
Degeneration of the cells in the brain
What genes cause alzeimers disease?
Mutation if the gene amyloid precursor protein - on chromosome 21 - explains why you are more likely to get it if you have down syndrome
mutations only explain 1% of prevalence of it, causes early onset
What have gene association studies found for alzeimers?
Risk genes for late onset AD - APOE3 increases risk, if you have one 1, copy of it, 2/3 times more likely
2 copies of APOE4 - 8/12 times more likely to get the disease
25% at least 1 APEO4 - 1/4 population have higher risk of it
What have twin studies shown about polygenetic factors?
Huntingdons is purely genetic as DZ twins have a 50% chance of getting it
Early onset AD - due to genes
Schizphrenia - 50% MZ twins, 15% DZ - shows environment too
Bipolar - 69% MZ, 13% DZ
Late onset AD is also environment
What is there a high correlation for in schizophrenia?
Between risk of developing it and genetic relationship - lots of separate genes which are present in schizophrenia
What have biological studies shown about schizophrenia?
Had to test over 150,000 people, to find 108 genes associated - lots of the genes were to do with synaptic transmission, glutamate and dopamine (D2 receptor)
