TPH2 and major depressive disorder: Genome‐wide studies have identified candidate genes and pathways linked to PPD, focusing on those associated with major depressive disorder like serotonin transporter, Tryptophan hydroxylase 2 (TPH2), Catechol‐O‐Methyltransferase, Monoamine oxidase, and Brain‐derived neurotrophic factor (BDNF) [20].