HLA-DRB1 and acquired polycythemia vera: Moreover, the allele DRB1*08:04 is associated with PV inBrazilian and Egyptian (DRB1*08:04-DQA1*05:01-DQB1*03:01),and Italian (possibly DRB1*08:04-DQA1*04:01-DQB1*04:02)populations.