Along with human leukocyte antigen gene encoding B*51 (HLA-B*51) and areas including the major histocompatibility complex class I, genome-wide association studies have recognized numerous other BD susceptibility genes including those encoding interleukin (IL)-10, IL-12 receptor β 2 (IL-12RB2), IL-23 receptor (IL-23R), C-C chemokine receptor 1 gene, signal transducer and activator of transcription 4 (STAT4), endoplasmic reticulum aminopeptidase (ERAP1), and genes encoding killer cell lectin-like receptor family members (KLRC4-KLRK1).
Behçet's disease (BD) susceptibility had been associated with single-nucleotide polymorphisms (SNPs) in IL23R-IL12RB2, IL10, STAT4, or ERAP1 locus in Japanese, Turkish, Chinese, and other populations, but not in a Korean genome-wide association study (GWAS).
Six SNPs (in decreasing order of significance, rs7616215 located 38 kb downstream of CCR1, rs2617170 [rs2617170;rs281860419" genes_norm="3107;8302">p.Asn104Ser] in KLRC4, rs17810546 in IL12A-AS1, rs7574070 in STAT4, and rs10050860 [rs10050860" genes_norm="51752">p.Asp575Asn] and rs13154629 in ERAP1) were nominally associated with BD in both allelic association tests (5.05 × 10(-9) ≤ Pallele ≤ 7.55 × 10(-3) ) and sex-adjusted genotypic association tests (6.01 × 10(-9) ≤ adjusted P value ≤ 1.30 × 10(-2) ).
We propose a model in which up-regulation of STAT4 expression and subsequent STAT4-driven production of inflammatory cytokines, such as IL-17, constitute a potential pathway leading to BD.
Our results indicate that the interaction of specific IL17A, IL23R, and STAT4 SNPs modulate susceptibility to intestinal BD in the Korean population, suggesting that the IL-17/23 axis plays a significant role in disease pathogenesis.