HLA-DRB1 and myeloid sarcoma: This difference in genetic susceptibility is suggested by human leucocyte antigen (HLA) haplotyping studies; a large study on bone marrow donors in Singapore showed that Indians have the highest frequency of the HLA-DRB1*15:01 allele (the HLA allele reported to have strongest effect on MS risk) while another study from India confirmed the association between MS with the HLA-DRB1*15:01 allele20,21.