An Information Theoretical Study of the Epistasis Between the CNR1 1359 G/A Polymorphism and the Taq1A and Taq1B DRD2 Polymorphisms: Assessing the Susceptibility to Cannabis Addiction in a Turkish Population.

Addiction is a complex, multi-factorial disease, and thus, analyzing genetic variants at multiple loci and gene-gene interactions among them (epistasis) can provide crucial clues about causative factors of addiction which cannot be detected with single-nucleotide polymorphism (SNP) association studies. In this study, we discuss the interaction between the 1359 G/A polymorphism of the CNR1 gene and the DRD2 gene polymorphisms and the net effect of any possible epistasis on the cannabis addiction phenotype in a Turkish population. Using bivariate synergy and mutual information concepts as a means of capturing the magnitude of interaction between marker pairs, the present study not only confirms the A1 marker allele as a risk factor but also reveals a finer-grained association between A and B markers which manifests itself both as a preventive and a risk factor.