SLC6A9 and major depressive disorder: Current clinical applications include the targeted treatment of hypertension (inhibition of SLC12A1/NKCC2 by diuretics), diabetes (inhibition of SLC5A2/SGLT2 by gliflozins), gout (inhibition of SLC22A12/URAT1 by lesinurad), schizophrenia (inhibition of SLC6A9/GLYT1 by bitopertin), and depression (inhibition of SLC6 transporters by serotonin-selective reuptake inhibitors) (Lin et al. 2015).