PCSK2 and type 1 diabetes mellitus: CHGA, HSPA1B, HSPA5, HSPD1, and IAPP are sources of known CD4 T cell epitopes associated with T1D, and PCSK2 and SCG5 are sources of known CD8 T cell epitopes.3 The previously identified MHC-I or MHC-II epitopes within these proteins differ from the peptides we observed likely because of the binding preferences of the particular HLA alleles in our donors, which in several cases have been genetically associated with an increased risk of T1D.