GEIRA is a tool designed to perform genome-wide gene-environment interaction analyses. It can be easily extended to genome-wide gene-gene interaction analyses on the condition that a genetic variable (such as SNP, CNV, Haptotype, etc.) can be dichotomized (0 = unexposed, 1 = exposed) as does an environmental variable.


GEIRA calculates measures of both additive and multiplicative interaction. Multiplicative interaction refers here to an interaction term in the logistic regression model. Additive interaction is defined as a deviation from additivity of the absolute effects of two risk factors as originally described by Rothman. The term, attributable proportion due to interaction (AP), is used to quantify the contribution of interaction to a disease risk, as compared with the contribution of each of the two risk factors added to each other.


Calculations were made separately based on dominant, recessive and co-dominant genetic models. The program is coded in both SAS and R. GEIRA (SAS version) was written using the SAS macro language and incorporates procedures in SAS/Base (SAS 9.2) and GEIRA (R version) was developed using the R version 2.6.2. However, use of GEIRA requires no previous experience on SAS or R.



To get started with , use the links on the left. You find Users manual, sample datasets and program on th left menu under GEIRA, SAS-version or GEIRA, R-version