As above described, BPD core depressive symptoms have been hypothesized to involve multiple neurobiological substrates, such as opioidergic and oxytocinergic neurotransmission, and specific monoamine receptors, such as dopamine D2 and serotonin 2A receptors, which interplay with each others to generate the symptoms of comorbid MDD-BPD. The gene discussed is HTR2A; the disease is Borderline personality disorder.