Question: additive and multiplicative genetic models in logistic regression
0
gravatar for TK
5.1 years ago by
TK0
Finland
TK0 wrote:

Hi all,

this may be a silly question but I'm a bit confused with the information I can find regarding the difference between additive and multiplicative genetic models. I understand that for a bi-allelic locus, and a binary outcome, the risk of heterozygotes (e.g. AG) in relation to the reference genotype (say AA, withr risk=1) in both models is for example k, and that in the additive model the risk of the homozygote GG is 2k and in a multiplicative model this is k², like this:

Model AA AG GG
additive 1 k 2k
multiplicative 1 k

I also found out that the allelic association test (G vs.A) assumes (and tests for ?) the multiplicative model and that additive assosiation can be achieved with a trend test.

I have been trying to find out what is the difference between these if I want to run them in a logistic regression, but I only find instructions for coding the both models like this: AA=0, AG=1, GG=2, and all the sources only discuss either one of these models, never both. So which model this coding actually represents (multiplicative?), and how do I code the other?

How about running these in PLINK, I understood that the basic logistic regression (with the --logistic option) offered there is a multiplicative model, how do I then get an additive model?

Many thanks,

Kristiina

snp • 4.3k views
ADD COMMENTlink written 5.1 years ago by TK0
Please log in to add an answer.

Help
Access

Use of this site constitutes acceptance of our User Agreement and Privacy Policy.
Powered by Biostar version 2.3.0
Traffic: 2287 users visited in the last hour