SNPs and a general downward correction of P values. Although, as the authors state, it might be (too) early to explore the biological relevance of the strongest observed associations, it is a fact that the list contains a number of very interesting candidate genes for ADHD (Table 1), most notably those genes that also show association in the GWAS of quantitative ADHD-related phenotypes (Lasky-Su et al. 2008b), as indicated in Table 1. Among these is a SNP close to CNR1, which encodes the cannabinoid receptor 1, a gene that falls into a linkage region for ADHD from a primary analysis (Ogdie et al. 2004) and shows suggestive linkage in meta-analysis (Zhou et al. 2008c). CNR1 was also found associated with the disorder in candidate gene-based association studies (Lu et al. 2008; Ponce et al. 2003). Furthermore, association of CNR1 with alcohol and drug abuse and dependence has been observed (Zuo et al. 2007). Also of interest are the findings for the especially brain-expressed cytoskeleton-organizer DCLK1 and the extracellular matrix component SPOCK3, as well as the two potassium-channel regulators KCNIP1 and KCNIP4 (Table 1).
