This study supports the notion that non-Dsg antibodies such as those directed against anti-TPO and-Tg may be of relevance in patients lacking the typical PV-associated alleles, since we show the highest levels of both antibodies in either DRB1*0804 positive patients or those lacking all 3 susceptibility alleles (DRB1*0402-, DQB1*0503- and DRB1*0804-triple negative). The gene discussed is TPO; the disease is acquired polycythemia vera.