Associations of serotonin transporter gene promoter polymorphisms and monoamine oxidase A gene polymorphisms with oppositional defiant disorder in a Chinese Han population

BACKGROUND: Oppositional defiant disorder (ODD) is a behavioral disorder that mainly refers to a recurrent pattern of disobedient, defiant, negativistic and hostile behaviors toward authority figures. Previous studies have showed associations of serotonin transporter (5-HTT) and monoamine oxidase A (MAOA) with behavioral and psychiatric disorders. The purposes of this study were to investigate the potential association of 5-HTT gene promoter polymorphism (5-HTTLPR) and MAOA gene polymorphism with susceptibility to ODD in a Han Chinese school population. METHODS: The 5-HTTLPR gene polymorphism and the MAOA gene polymorphism were genotyped in a case–control study of 257 Han Chinese children (123 ODD and 134 healthy controls). RESULTS: There was significant difference in the allele distribution of 5-HTTLPR (χ(2) = 7.849, P = 0.005) between the ODD and control groups. Further, there were significant differences in genotype (χ(2) = 5.168, P = 0.023) and allele distributions (χ(2) = 10.336, P = 0.001) of the MAOA gene polymorphism that is variable-number tandem repeat (MAOA-uVNTR) between two groups. Moreover, there were significant differences in genotype (χ(2) = 4.624, P = 0.032) and allele distributions (χ(2) = 9.248, P = 0.002) of MAOA-uVNTR only in the male ODD and healthy groups. CONCLUSIONS: Our results suggest that 5-HTTLPR and MAOA-uVNTR gene variants may contribute to susceptibility to ODD. Further, MAOA-uVNTR gene polymorphism may play a role in susceptibility to ODD only in male children.