PE-DIF for IgG and IgA was performed on histopathologically confirmed 15 PV cases, three PF cases, four BP cases, three DH cases, three subcorneal pustular dermatosis (SCPD) cases, one case of linear IgA disease, and one case of pemphigoid gestationis (PG) (Table 1). The gene discussed is CD79A; the disease is acquired polycythemia vera.