h2 = 0.37–0.71) and total problems (SNP h2 = 0.18). A previous attempt to discover genomic locations of interest for childhood and adolescent aggression (N = 18,988) identified one region in chromosome 2 (2p12) at near genome-wide significance (top SNP rs11126630, P = 5.30 × 10− 8). The gene-based analysis indicated association with variation within AVPR1A with aggressive behaviour. It was concluded that common variants at 2p12 show suggestive evidence for association with childhood aggression [41]. To replicate this finding and to initiate new findings we will use newly developed multivariate genome-wide meta-analysis methodology, in which the power of sample overlap (e.g. due to having a paternal and maternal rating of the same child at the same age) is leveraged instead of omitted [42]. In line with the results, we include ADHD and ADHD-related problems, as well aggressive behaviour in this collaborative project. With this approach, we will be able to identify not only genomic regions of interest for aggression or ADHD, but also genomic regions that play a role in the co-occurrence of these psychopathologies.
