HLA-DRB1 and myeloid sarcoma: Importantly, in the recent fine mapping effort with 1,068 SNPs covering the HLA locus and providing the SNP density of 1 SNP per 2 kilobases in the study sample of 4,200 individuals from Finnish and Canadian MS families [29], susceptibility to MS proved to be determined by HLA-DRB1 alleles and their interactions.