DSG1 and acquired polycythemia vera: Interestingly, of all DQB1*0503 positive PV patients, South Asian patients display higher anti-Dsg1 autoantibody levels (mean 66.5 +/- 56.9 IU/ml, 63% positive) than DQB1*0503 positive patients of all other ethnicities combined (36.7 +/- 59.7 IU/ml, 31% positive)(Supplemental Figure 1), indicating that both HLA expression as well as ethnicity can be considered independent risk factors for development of anti-Dsg1 autoantibodies.