Hi,

Does anyone know how to do analysis of Joint Risk Genotype Interaction?

I did case-control study analyzing the effect of polymorphism (HTRA and ARMS) on AMD disease. I have excluded all missing data in analysis.


I used these codes:

. logistic Outcome i.HTRA##i.ARMS

HTRA: 1=GG 2=GA 3=AA
ARMS: 1=GG 2=GT 3=TT
AMD (Outcome): 1=disease 0=no disease

It resulted :
note: 2.HTRA#1.ARMS != 0 predicts failure perfectly
2.HTRA#1.ARMS dropped and 1 obs not used

note: 3.HTRA#1.ARMS != 0 predicts failure perfectly
3.HTRA#1.ARMS dropped and 3 obs not used

note: 2.HTRA#3.ARMS omitted because of collinearity
note: 3.HTRA#3.ARMS omitted because of collinearity

My expectation is that I can get the OR for
HTRA GG vs ARMS GG = reference
HTRA GG vs ARMS GT
HTRA GG vs ARMS TT
HTRA GA vs ARMS GG
HTRA GA vs ARMS GT
HTRA GA vs ARMS TT
HTRA AA vs ARMS GG
HTRA AA vs ARMS GT
HTRA AA vs ARMS TT

I don't know why I can't get OR for all 9 possibilities.
Array