Some studies have investigated combined effects of 5-HT1A and 5-HTT genotypes, e.g. in major depression, mediating the influence of negative life events [65] and 5-HT1A */G and 5-HTTlow showing increased amygdala response to emotional stimuli [66], though results were not entirely consistent [67]. This evidence concerns the gene SLC6A4 and major depressive disorder.