Association of DNA polymorphism in the first intron of the tyrosine hydroxylase gene with disturbances of the catecholaminergic system in schizophrenia.

We examined whether there are clinical or biological differences in chronic schizophrenic patients sharing a rare variant allele (a perfect ten tetranucleotide repeats allele of the human TH01 microsatellite) in the tyrosine hydroxylase (TH) gene. For that purpose, clinical parameters (PANSS subscores) and plasma measurements (homovanillic acid and 3-methoxy-4-hydroxy-phenylglycol (MHPG)) were analyzed in five schizophrenic patients sharing the rare allele and 19 schizophrenic patients who did not possess this allele. The mean concentration of plasma HVA and plasma MHPG were significantly lower in the group of schizophrenic patients sharing the rare allele. No other group differences were observed between both groups. These results suggest that this TH gene polymorphism may be associated with disturbances of the catecholaminergic pathway.