I have a question about odds ratios frequently used in papers.
If a A/C SNP is associated with Type 2 Diabetes and the C-Allele has an odds ratio of 1,31.... that means that if person is:
AA > OR 1
AC > OR 1,31
CC > OR ?
Now I personally think the odds ratio is 1,62 for CC homozygotes... but I have seen this very problem on snpedia.com where the result aparrently is 2,31.
What is the right answer?
Another question.... under the additive model when trying to find out the combined risk for a person:
OR for SNP 1 > 1.3
OR for SNP 2 > 1.7
OR for SNP 3 > 0.5
What is the combined odds ratio?
1+0,3+0,7-0,5= 1,5 ?
Is this right?
Also.. when no information is avaliable, what is the standard model to use for combining odds ratios of multiple unlinked SNP's?
Multiplicative or additive?
Thanks so much for your help.