The anatomical and functional interactions between mGluR2 and 5HT2A receptors have been reported to form heterodimeric complex that modulate G-protein-mediated intracellular signaling differentially compared to mGluR2 and 5-HT-2A homomers [68–71], and both human and animal pharmacological studies demonstrated that an interaction with 5-HT2A receptor can improve comorbid sleep disturbance associated with mood disorders and schizophrenia [72–75]. The gene discussed is HTR2A; the disease is mood disorder.