Significant associations with reduction in BMI at 6months following switching were found in two of these genes : with rs1800544 of the ADRA2A gene ( CC+CG [ -0.321.41 kg/m ] vs GG [ -1.041.63 kg/m ] , p = 0.013 ) and with rs1801131 of the MTHFR gene ( AA [ -0.361.53 ] vs AC+CC [ -1.071.53 ] , p = 0.015 ) .