An interesting new approach in GWAS is represented by the exploratory study by Sonuga-Barke et al. (2008). The author and his colleagues evaluated gene-environment interactions (G × E) in ADHD in a genome-wide analysis. Specifically, they investigated the effects of maternal warmth and criticism on ADHD severity in the GAIN/IMAGE dataset (also, a G × E analysis for conduct disorder symptoms is reported in the publication, but is not reviewed here). ADHD symptoms were derived from the PACS interview in IMAGE, maternal expressed emotion was assessed using the Camberwell Family Interview. Maternal warmth and criticism were coded, separately; warmth was assessed by tone of voice, spontaneity, sympathy and/or empathy toward the child. Criticism was coded from statements that criticized or found fault with the child based on the tone of voice and critical phrases (Sonuga-Barke et al. 2008). Statistical analysis made use of the FBAT-Interaction methodology (Vansteelandt et al. 2008). In total, 430,060 autosomal SNPs were included in the analysis, as were 909 patients (87% males) from complete trios. Mean age of the participants was 10.88 years, the average number
