NMDA: N-methyl-D-aspartate; 5-HT2A: 5-hydroxytryptamine receptor 2A; MDD: Major Depressive Disorder; GRID-HAMD: GRID-Hamilton Depression Rating Scale; QIDS-SR: Quick Inventory of Depressive Symptomatology-Self Rated; BP: Blood pressure; HR: Heart rate; MADRS: Montgomery–Åsberg Depression Rating Scale; ASD: Autism Spectrum Disorder; GABA: Gamma-aminobutyric acid; C-SSRS: Columbia Suicide Severity Rating Scale; SpO2: Saturation of peripheral oxygen; CDRS-R: Children's Depression Rating Scale-Revised; TRD: Treatment-Resistant Depression; SUD: Substance Use Disorder; ID: Intellectual disability. This evidence concerns the gene HTR2A and depressive disorder.