The most studied genes in pediatric populations are those encoding the dopamine inactivator catechol-O-methyl transferase (COMT), neurotrophin, brain derived neurotrophic factor (BDNF, (Casey et al. 2009; Knickmeyer et al. 2013; Mueller et al. 2013)), the schizophrenia candidate gene neuregulin (NRG1, (Knickmeyer et al. 2013)), and the serotonin transporter (5-HTT, (Pacheco et al. 2009; Lau et al. 2009; Wiggins et al. 2012)). Amongst these, the COMT genotype was the only one found to influence brain morphometry (Raznahan et al. 2011; Knickmeyer et al. 2013), white matter integrity (Thomason et al. 2010; Sundram et al. 2010) and brain connectivity (Mechelli et al. 2009). A longitudinal study in healthy children additionally demonstrated that a greater COMT Val158Met Val allele dose is associated with a decrease in the cortical thickness loss in the prefrontal cortex from 9 to 22 years of age (Raznahan et al. 2011). Genetic variants in the following genes APOE, DISC1, GAD1, GPCD1, ESR1, DYX1C1, DCD2, KIAA0319, HOXA1, DTNBP1, OXTR, MAOA, IL-6, MET and PER2, have been associated with neuroimaging phenotypes, raising the possibility that they may be involved in brain
