Neuropeptide Y (NPY) gene is associated with T2D121 and SCZ,122 but less consistently with SCZ.123 NPY is of interest to the hypothesized correlation of the dopamine–PRL pathway with the SCZ–T2D comorbidity, as NPY appears, beyond stimulating appetite, to amplify the inhibitory action of dopamine on PRL secretion.124 Thus, an altered NPY pathway may have effects on the dopamine–PRL pathway. The gene discussed is PRL; the disease is type 2 diabetes mellitus.