Association of dopamine β-hydroxylase polymorphism rs1611115 and serum levels with psychiatric disorders in Pakistani population

Dopamine β-hydroxylase (DBH) is a copper-containing enzyme that has an important role in maintaining the cellular homeostasis between the two neurotransmitters, dopamine (DA) and nor-adrenaline (NA). DBH functional polymorphisms are associated with multiple neuro-psychiatric conditions and are found to alter the DBH protein levels in serum, affecting DBH enzymatic activity. The current study was conducted to determine the genetic association of DBH functional polymorphism rs1611115 and its effect on DBH levels in serum in major depressive disorder (MDD), bipolar disorder (BPD) and schizophrenia (SHZ) in the Pakistani population. In total n = 1097 subjects including MDD (n = 427), BPD (n = 204), SHZ (n = 134) and healthy controls (n = 332), were screened for rs1611115 by polymerase chain reaction-restriction fragment length polymorphism. Univariate logistic regression was applied and results were adjusted for age and sex (multivariant analysis). The DBH levels in serum were determined through enzyme-linked immunosorbent assay (ELISA) and the Mann Whitney U test was applied. The results showed a significant association of minor allele (-1021C > T) with a higher risk of developing BPD and SHZ in both univariable and multivariable analyses. Moreover, the overall total serum concentration of DBH was comparatively raised in MDD, however, in cross-comparison DBH serum levels were found markedly higher in CC homozygotes compared to TT homozygotes within the BPD group. Thus the present study suggested a significant association of DBH rs1611115 with BPD and SHZ and also the effect of rs1611115 on DBH serum levels in MDD and BPD, for the first time in the Pakistani population.