Association of familial Mediterranean fever-related MEFV variations with ankylosing spondylitis.

OBJECTIVE: The pathogenesis of ankylosing spondylitis (AS) has a strong genetic contribution. Familial Mediterranean fever (FMF) is an autosomal recessively inherited autoinflammatory disorder caused by MEFV gene missense variations, and a clinical association between FMF and AS has been reported previously. The aim of this study was to analyze the association of common MEFV variations (M694V, M680I, V726A, and E148Q) with AS in a group of Turkish patients. METHODS: The study group comprised 193 patients with AS and 103 matched healthy control subjects. All individuals were genotyped for 4 MEFV variations and HLA-B27 using genomic DNA, and association of the variations with the clinical and laboratory features of the patients was analyzed. RESULTS: The MEFV missense variations were significantly more frequent in patients with AS (22.3%) compared with healthy control subjects (9.7%; odds ratio [OR] 2.67, 95% confidence interval [95% CI] 1.28-5.56). This difference was more prominent for exon 10 variations (M694V, V726A, M680I) (OR 3.75, 95% CI 1.41-9.97), especially for the most-penetrant variation M694V (OR 4.73, 95% CI 1.39-16.12). MEFV variations were more frequent in HLA-B27-negative patients with AS, and the difference was statistically significant in patients carrying exon 10 variants. CONCLUSION: FMF-related MEFV variations are associated with AS, and these variations may contribute to the pathogenesis of AS, especially in populations in which the prevalence of FMF is high.

No association of the TLR2 gene Arg753Gln polymorphism with rheumatic heart disease and Behçet's disease.

Behçet's disease (BD) is a multisystem inflammatory disorder of unknown etiology, and infections with different microorganisms including streptococci have been claimed as triggers of inflammatory attacks in BD pathogenesis. Toll-like receptor 2 (TLR2) has been known to recognize several microbial antigens including that of streptococci, and TLR2 gene Arg753Gln polymorphism has been reported to be strongly associated with acute rheumatic fever with an odds ratio of 100. This study aimed to investigate the TLR2 gene Arg753Gln polymorphism in a group of patients with BD and rheumatic heart disease (RHD) and to analyze the role of genotyping errors resulting from duplicated gene segments. The study group consisted of 211 patients with BD, 95 patients with RHD, and 94 matched Turkish healthy controls. Because of the duplicated exon 3 in 23-kb upstream of the TLR2 gene, genotyping for the Arg753Gln polymorphism with polymerase chain reaction-restriction fragment length polymorphism method was carried out using a new set of primers and PstI restriction enzyme. TLR2 gene Gln753 allele was observed in two of 211 (1.0%) patients with BD, five of 95 (5.3%) patients with RHD, and two of 94 (2.1%) healthy controls. All patients and controls were found to be heterozygous for Arg753Gln polymorphism, except one patient with BD, who was homozygous for Gln753. Although a slight increase of heterozygosity was noted in patients with RHD, no statistically significant difference was observed in the distribution of Arg753Gln polymorphism in BD and RHD compared to healthy controls. In conclusion, TLR2 gene Arg753Gln polymorphism is not associated with BD nor with RHD; and a duplicated region of the TLR2 exon 3 located 23-kb upstream of the polymorphic region may explain contradictory association findings described so far.

Polymorphisms of the IL-8 and CXCR2 genes are not associated with Behçet's disease.

OBJECTIVE: Genetic susceptibility to Behçet's disease (BD) is well documented for HLA-B51; however, contribution of other genetic polymorphisms is estimated to be substantial. Interleukin 8 (IL-8), a potent chemoattractant for neutrophils, has been found to be elevated in BD serum, and the serum concentrations correlate with disease activity. Novel polymorphisms in IL-8 (CXCL8) and in one of its receptors, CXCR2 gene, may have a role in enhanced IL-8 activity in BD. METHODS: Three single nucleotide polymorphisms (SNP; -353 A/G, +1530 T/C, +3331 A/G) of the IL-8 gene and 2 SNP (+785 C/T and +1208 T/C) of the CXCR2 gene were screened in 100 patients with BD (61 men, 39 women, mean age 42.1 yrs) and 100 healthy controls (50 men, 50 women, mean age 36.8 yrs) by genotyping with PCR-RFLP and PCR-SSP methods. RESULTS: No differences were observed between BD patients and controls for the allele and genotype frequencies of the screened IL-8 and CXCR2 gene polymorphisms. Distribution of these polymorphisms revealed no significant differences between clinical subgroups of BD patients. Each pair of the SNP -353/+1530, -353/+3331, and +1530/+3331 of IL-8 and +785/+1208 of CXCR2 showed strong linkage disequilibrium in both patients and controls (p < 0.001 for all). The distribution of the estimated IL-8 and CXCR2 haplotypes revealed no association with BD or any of its clinical subsets. CONCLUSION: These results suggest that the IL-8 gene -353 A/G, +1530 T/C, and +3331 A/G and the CXCR2 gene +785 C/T and +1208 T/C polymorphisms have no role in the increased expression of IL-8 in BD.