Further analysis showed that the high-activity allele of MAOA-uVNTR may increase the risk for ODD in children, whilst the low-activity allele may be a protective factor, which are consistent with previous studies showing that MAOA-uVNTR was associated with impulsive behaviors and alcohol dependence [35], aggressive behaviors [36, 37] and suicide attempts in patients with major depressive disorder [38]. Here, MAOA is linked to Oppositional defiant disorder.