MAOA and attention deficit-hyperactivity disorder: CM was shown to have a significant impact on ADHD symptoms among a sample of young people, particularly in the case of females, while the combination genetic effects of MAOA (rs1137070 C > T), BDNF (rs6265 C > T), and COMT (rs4680 G > A), which reflected individual susceptibility, were significant in terms of the association with hyperactivity symptoms in both genders.