Additionally, a meta-analysis has suggested that SNPs within ATXN1 are associated with intelligence quotient in the background of ADHD [45] and Bremer et al. [22] proposed that haploinsufficiency of ATXN1 may therefore contribute to the learning difficulties observed in the patients harboring a 6p22 deletion. This evidence concerns the gene ATXN1 and attention deficit-hyperactivity disorder.