Immunogenetics of Behçet's disease: Is there a link to recent phenotypic changes?

Over the past decade, advances in genetic and genomic analyses, including genome-wide association studies, have provided substantial insights into the pathogenesis of Behçet's disease (BD). These studies revealed potential pathogenic mechanisms such as the preparation and presentation of peptides by HLA Class I antigens, mainly HLA-B51, and endoplasmic reticulum aminopeptidase 1, recognition of presented peptides by CD8 T cells, dysregulated innate and adaptive immune response, including autoinflammation, activation of Th17 cells, natural killer cells, and M1-polarized macrophages, as well as disordered mucosal barrier defense. The genetic architecture of BD shares similarities with Crohn's disease, spondyloarthritis, as well as childhood-onset autoinflammatory diseases such as familial Mediterranean fever, A20 haploinsufficiency, periodic fever, aphthous stomatitis, pharyngitis, cervical adenitis syndrome, or late-onset autoinflammatory diseases such as VEXAS syndrome and trisomy 8-related autoinflammatory diseases. This review summarizes the current understanding of the immunogenetic basis of BD, emphasizing how the interplay between changing environmental exposures and inherited or acquired genetic variants contributes to its heterogeneous and variable phenotypic expression.