Taking together all results from the GWAS performed in ADHD, the following is to be remarked: none of the findings so far show genome-wide significant association with ADHD according to the thresholds currently handled (Dudbridge and Gusnanto 2008; Pe’er et al. 2008; van Steen and Lange 2005). Nevertheless, the most high-ranking findings from the different studies contain interesting new candidates for further study. Little overlap is observed between studies, except for CDH13, which is found in three studies (Lasky-Su et al. 2008b; Lesch et al. 2008; Neale et al. 2008a). None of the ‘classic’ candidate genes for ADHD are found among the top-findings of either study, although two more recently reported genes, NOS1 and CNR1, are observed at least once. In the candidate gene analyses reported for the GAIN/IMAGE sample, most evidence is repeatedly found for involvement of SLC9A9 in ADHD. For all studies discussed here, overlap with results from linkage studies reported in ADHD and linkage as well as GWAS in other psychiatric disorders is multiple.
