SLC6A4 and Sudden unexpected death in epilepsy: Immunohistochemical studies on postmortem human SUDEP cases, showed that there is decreased 5-HT synthesizing enzyme (Tryptophan hydroxylase 2, TPH2), 5-HT presynaptic transporter (SERT) in medullary raphe, indicating that there is loss of serotonergic neuronal synthesizing capacity and reuptake mechanisms in SUDEP patients [80].