HLA-DRB1 and eosinophilic granulomatosis with polyangiitis: Several small cohort candidate-gene studies of Italian and German EGPA patients indicate genetic association with HLA alleles—HLA-DRB4 (increases the likelihood of vasculitic manifestations), DRB1*07, DRB3 (reduced frequency in EGPA versus controls) and DRB1*13 (also underrepresented in the EGPA cohort) [61,95].