To independently replicate the top findings from 4 published genome-wide association studies (GWAS) of susceptibility genes in Behçet's disease (BD).
We tested 14 single-nucleotide polymorphisms (SNPs) in 13 genomic loci (excluding the major histocompatibility complex [MHC], IL10, and IL23R-IL12RB2, which have already been associated with BD in Iranians) for allelic and genotypic associations with BD in 973 patients and 828 controls from Iran and performed meta-analyses of the significantly associated markers.
Six SNPs (in decreasing order of significance, rs7616215 located 38 kb downstream of CCR1, rs2617170 [p.Asn104Ser] in KLRC4, rs17810546 in IL12A-AS1, rs7574070 in STAT4, and rs10050860 [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) ). For all 6 SNPs tested by meta-analysis (Pmeta ), the association with BD was strengthened, because the direction and magnitude of association were similar across populations (e.g., for rs7574070, odds ratio [OR] for A allele 1.29 [95% confidence interval (95% CI) 1.21-1.37], Pmeta  = 2.34 × 10(-16) ; for rs7616215, OR for C allele 0.70 [95% CI 0.65-0.76], Pmeta  = 1.54 × 10(-19) ; for rs17810546, OR for A allele 0.60 [95% CI 0.52-0.70], Pmeta  = 6.34 × 10(-11) ; for rs2617170, OR for T allele 0.76 [95% CI 0.70-0.81], Pmeta  = 2.75 × 10(-14) ; for rs13154629, OR for TT genotype 2.76 [95% CI 2.01-3.80], Pmeta  = 3.57 × 10(-10) ).
This study reinforces the notion that CCR1, KLRC4, IL12A-AS1, STAT4, and ERAP1 are bona fide susceptibility genes for BD, in addition to the MHC, IL10, and IL23R-IL12RB2 loci. Future genetic and functional studies are now warranted to uncover the roles of these genes in the pathogenesis of BD.