SLC6A3 and schizophrenia: We have previously reported dysregulation of multiple DA-related mRNAs in the midbrain in schizophrenia, including lower gene expression of DA receptor D2 isoforms (DRD2short, and DRD2long), DA transporter (DAT), vesicular monoamine transporter (VMAT), and a synthesis enzyme (aromatic acid decarboxylase) [17].