Our approach, which uses a validation set as indication of a true association, has proven successful in other GWAS as exemplified by the identification of IL7RA and IL2RA susceptibility alleles in multiple sclerosis (MS) where no SNPs in either gene met genome-wide significance in the discovery dataset, but were confirmed through validation in an additional dataset (International Multiple Sclerosis Genetics Consortium et al. 2007). These MS findings recently have been confirmed across numerous datasets (International Multiple Sclerosis Genetics Consortium (IMSGC) 2008). We also note that other such common variants are likely to exist in autism and further GWAS studies are warranted.
