SLC6A3 and schizophrenia: Consistent with this view, a genetic linkage study in schizophrenia patients found no associations between variation of dopamine receptor genes and P50 gating.126 A later study that examined the effects of genetic variation in a dopamine transporter 1 gene found that healthy subjects that may have higher dopamine levels due to hypoexpression of dopamine transporter 1 showed improved gating, suggesting that dopaminergic blockade may actually worsen gating in some individuals.127