Using EMSA, as a preliminary functional test for the three polymorphisms in IRF5 that gave the strongest association signals with MS, we observed stronger protein binding to the risk alleles of the SNP rs4728142 (the A allele) and of the CGGGG indel polymorphisms (the 4×CGGGG allele), whereas both alleles of the SNP rs3807306 appear to bind an equal amount of protein. Here, IRF5 is linked to myeloid sarcoma.