CHRNA4 and type 2 diabetes mellitus: The GMDR has been successful in identifying the significant interaction of CHRNA4 with CHRNB2[21], NTRK2 with BDNF[21], and GABBR1 with GABBR2[22] in nicotine dependence, of LEPR and ADRB2 in obesity [23], and of HNF4A and KCNJ11 in type 2 diabetes (T2D) [24].