“…9 The theory that PV is inherited had been initially suggested by the unique susceptibility of some ethnic groups and populations such as Ashkenazi Jewish and people from India and the Mediterranean. 16 The association between HLA class II alleles and PV has been shown in many different ethnic groups, such as Brazilians, 13 Venezuelans, 3 Argentinians, 17 Spanish, 18 French, 19 Iranians, 20 Italians and Sardinians, [21][22][23] Japanese, [24][25][26][27] Ashkenazi Jews, 28 Mexicans, 29 North-Americans, [30][31][32] Pakistanis, 33 Syrians, 10 Middle-Eastern groups, 16 Slovacs, 34 and Canadians, 35 associating nine DR alleles DRB1*0402, *0403, *0406, *0802, *0804, *1401, *1404, *1405, *1408 and four DQ alleles DQB1*0302, DQB1*0503, DQA1*0101, and DQA1*0301 with the disease. 11,12 The association between PV and human leukocyte antigen (HLA) was shown in the 1980s and has repeatedly been proven through laboratory and serologic tests.…”