Association of polymorphic VNTR region in the first intron of the human TH gene with disturbances of the catecholamine pathway in schizophrenia.

In the present study, five allelic fragments were typed by a polymerase chain reaction (PCR) process with a pair of primers specific for the tetranucleotide (TCAT) repeat sequence in the first intron of the human tyrosine hydroxylase (TH) gene and their sizes (bp) were 114 (A), 118 (B), 122 (C), 126 (D) and 130 (E), respectively. The AE genotypic frequency was found to be significantly higher in unrelated patients with schizophrenia than in unrelated control subjects (chi 2 = 4.18, p < 0.05). ANOVA revealed a significant difference between the three groups (neuroleptic-free patients possessing or not possessing the AE genotype, and unrelated control subjects) in the concentration of serum noradrenaline (F = 4.96, df = 2.79, p < 0.01), but no significant differences were found between the three groups in the concentrations of serum homovanillic acid, phenylalanine and tyrosine. These results suggest that the polymorphic intron 1 of the human TH gene may be associated with disturbances of the catecholamine pathway in schizophrenia.