The dopamine beta-hydroxylase gene polymorphism rs1611114 is associated with schizophrenia in the Chinese Zhuang but not Chinese Han population

Schizophrenia (SCZ) is a devastating neurodevelopmental disorder. However, the mechanism underlying this highly heritable disorder remains unclear. The dopamine beta-hydroxylase (DBH) gene encodes a key metabolic enzyme of dopamine. Consequently, DBH is considered a candidate gene for SCZ. However, previous studies on its association with SCZ susceptibility have shown conflicting results. Here, we examined association between the rs1611114 polymorphism of DBH and SCZ susceptibility and related clinical symptoms. A total of 691 SCZ patients and 698 age- and gender-matched healthy controls were examined. mRNA expression levels of DBH were measured by quantitative real-time polymerase chain reaction, and the rs1611114 polymorphism was genotyped using the Sequenom MassARRAY platform. Also, the Positive and Negative Syndrome Scale (PANSS) was used to assess SCZ clinical symptoms. Our results show lower DBH mRNA expression levels in SCZ patients than healthy controls (Zhuang: p = 0.000; Han: p = 0.037). Interestingly, the rs1611114 polymorphism was significantly associated with SCZ susceptibility (overdominant model: p = 0.010) in only the Chinese Zhuang population. Furthermore, the rs1611114 polymorphism was associated with PANSS total score (allele T/C: p = 0.015) and general psychopathology score (allele T/C: p = 0.027) in Chinese Zhuang SCZ patients. These results suggest that the DBH gene may play an important role in the occurrence of SCZ. Also, rs1611114 may be associated with SCZ susceptibility and related clinical symptoms in the Chinese Zhuang but not Han Chinese population. Further studies with larger samples of different ethnicities are needed to confirm the role of DBH in SCZ.