SLC6A4 and anxiety disorder: Multiple studies examining the genetics of differential response to psychological therapies (therapygenetics8) have been undertaken, and variants in seven genes (5HTT/SLC6A4, TPH2, MAOA, COMT, NGF, BDNF and GRIK4) have been implicated at least once in studies of CBT for anxiety disorders.9 However, findings have proven difficult to replicate,10 and the direction of effects found inconsistent.