Is the polymorphic microsatellite repeat of the dopamine beta-hydroxylase gene associated with biochemical variability of the catecholamine pathway in schizophrenia?

Six allelic fragments were typed by a polymerase chain reaction process with a pair of primers specific for a sequence containing the polymorphic (GT)n repeat, a microsatellite repeat, in the human dopamine beta-hydroxylase (DBH) gene. Their frequencies in unrelated patients with schizophrenia were 0.003 (A1), 0.114 (A2), 0.343 (A3), 0.526 (A4), 0.006 (A5), and 0.009 (A6), and in unrelated control subjects, 0.012 (A1), 0.086 (A2), 0.309 (A3), 0.574 (A4), 0.006 (A5), and 0.012 (A6). Kruskal-Wallis analysis revealed significant differences among the three groups, the drug-free and drug-treated patients, and the control subjects, in serum DBH activity of the subjects whose genotype was A2/A3 (H = 6.0, p