While shortening or lengthening of TH-positive processes has not been reported in neuropsychiatric disease, both schizophrenia and autism have been associated with increased tyrosine hydroxylase staining in substantia nigra17 as well as abnormal dopamine and dopaminergic receptor levels in substantia nigra, striatum and prefrontal cortex17, 18. This evidence concerns the gene TH and schizophrenia.