HLA-DRB1 and myeloid sarcoma: We further analyzed frequencies of heterozygous genotypes including one risk allele (HLA-DRB1*03 or *15) and one resistance allele (HLA-DRB1*01 or *11), i.e., *01/*15, *11/*15, *01/*03, and *11/*03 in MS patients and healthy individuals.