GNB3 and type 2 diabetes mellitus: Some of the gene-gene interactions may be more subtle than just pair-wise interactions, e.g. in predisposition to T2DM, there are pair-wise interactions between APOB(Thr7Ile) and CETP(Ile 405Val), but also between APOB(Thr7Ile) and GNB(C825T), so CETP and GNB3 polymorphisms may influence each-other via the APOB polymorphism or, alternatively, the effect of the APOB polymorphisms may be influenced by variations in both CETP and the GNB3.