MDD subtype 2 patients exhibited associations with a distinct neurochemical profile characterized by serotonergic (5‐HT1a), endocannabinoid (CB1), dopaminergic (D1, FDOPA), GABAergic (GABAa), and glutamatergic (NMDA, mGluR5) systems. The gene discussed is GRM5; the disease is major depressive disorder.