The first MS GWAS (The International Multiple Sclerosis Genetics Consortium et al., 2007) was performed on 931 family trios and identified variants in the interleukin-7 receptor (IL7R) and in the interleukin-2 receptor (IL2RA) loci (Gregory et al., 2007; Weber et al., 2008), again pointing to the crucial role played by the immune system. Here, IL2RA is linked to myeloid sarcoma.