DPP6 and Tourette syndrome: Interestingly, in a mouse model, DPP6 expression is increased in the prefrontal, striatal, hippocampal and ventricular midbrain brain regions after 50 weeks’ long-term administration of haloperidol, which is an antipsychotic drug that reduces the level of excitement in schizophrenia, Tourette’s syndrome and severe behavioral problems in children.