Regarding the fact that pemphigus vulgaris-relevant HLA alleles are restricted to the DRB and DQB loci and strong linkage disequilibrium of DRB1*04:02 with DQB1*03:02 and of DQB1*05:03 with DRB1*14:54, we can conclude that DRB1*04:02 and, to a lesser extent, DQB1*05:03 are risk alleles for PV in Croatia. The gene discussed is HLA-DRB1; the disease is acquired polycythemia vera.