HLA-DRB1 and myeloid sarcoma: The HLA-DRB1*15:01 allele has been shown to be a risk allele in Ashkenazi [13], but it is less frequent in Ashkenazi (~5 %) [11, 16] compared to the general European population (~15-20 %), which is a counterintuitive observation given the high frequency of MS among Ashkenazi.