Another interesting question is why the subgenual cingulate cortex (sACC) [98], [99], which shows the highest cortical 5-HTT binding in post mortem studies [78] and in own PET data (Figure S9, Text S1, and Table S4), has not been found to be the main peak of correlation with platelet Vmax within this study given its repeated implication in depression neurobiology [98] and therapy [99]. Here, SLC6A4 is linked to major depressive disorder.