DSG3 and acquired polycythemia vera: As DQB1*0301 also has this aspartic acid,19 and crucial roles of the amino acid at position DQβ57 in the binding of antigenic peptides have been reported,20 the structural similarity between DQB1*0503 and DQB1*0301 was attributed to this observation in the study that HLA‐DQB1*0301, the allele rarely seen in PV patients, was the restricted allele for Dsg3 presentation to T cells.