HLA-DRB1 and myeloid sarcoma: We have identified several MHC-specific MS susceptibility variants in the admixed African American and Hispanic samples which are rare in European populations and represent novel population-specific effects, and we have also utilized the differing LD patterns in Hispanics and African Americans to confirm an independent role for HLA-DRB1*15:01 and HLA-DQB1*06:02 on MS risk.