ERAP1 and Behcet disease: In this review, we will focus on the so-called “mis-peptidome” by discussing a potential harmful role of the suboptimal and self-immunopeptidome in the “MHC-I-opathies”, the influence of ERAP1 and ERAP2 allelic variants and the implication in the onset of AS and related SpA, BD, Ps and BSCR.