With attention to multifaceted features in subjects with early-onset behavior problems as i.e., higher irritability, anxiety, impulsivity, possibly associated with an impaired hypothalamic-pituitary-adrenal (HPA) function, Dadds et al. (34) examined the methylation patterns of the NR3C1 promoter exon 1F in whole blood and saliva cell DNA and the morning plasma cortisol levels within a study collective (n = 241, 51 female) with full criteria or features of conduct disorder (CD) or oppositional defiant disorder (ODD) in contrast to an Australian normative sample as control (35). This evidence concerns the gene NR3C1 and Oppositional defiant disorder.