COMT and major depressive disorder: Inoue et al. have shown that transmembrane protein 132D (TMEM132D), COMT, and GABA receptor alpha 6 subunits (GABRA6) genotypes are associated with emotional processing in the cingulate, frontal cortex, and hippocampus in panic disorder and major depressive disorder (MDD) (Papaleonidopoulos et al., 2018).