Takayasu arteritis is a rare inflammatory disease of large arteries. The etiology of Takayasu arteritis remains poorly understood, but genetic contribution to the disease pathogenesis is supported by the genetic association with HLA-B*52. We genotyped ~200,000 genetic variants in two ethnically divergent Takayasu arteritis cohorts from Turkey and North America by using a custom-designed genotyping platform (Immunochip). Additional genetic variants and the classical HLA alleles were imputed and analyzed. We identified and confirmed two independent susceptibility loci within the HLA region (r(2) < 0.2): HLA-B/MICA (rs12524487, OR = 3.29, p = 5.57 × 10(-16)) and HLA-DQB1/HLA-DRB1 (rs113452171, OR = 2.34, p = 3.74 × 10(-9); and rs189754752, OR = 2.47, p = 4.22 × 10(-9)). In addition, we identified and confirmed a genetic association between Takayasu arteritis and the FCGR2A/FCGR3A locus on chromosome 1 (rs10919543, OR = 1.81, p = 5.89 × 10(-12)). The risk allele in this locus results in increased mRNA expression of FCGR2A. We also established the genetic association between IL12B and Takayasu arteritis (rs56167332, OR = 1.54, p = 2.18 × 10(-8)).

Behçet's disease is an inflammatory disease characterized by recurrent oral and genital ulcers and significant organ involvement. Localizing the genetic association between HLA-B*51 and Behçet's disease and exploring additional susceptibility loci in the human leukocyte antigen (HLA) region are complicated by the strong linkage disequilibrium in this region. We genotyped 8,572 variants in the extended HLA locus and carried out imputation and meta-analysis of 24,834 variants in 2 independent Behçet's disease cohorts from 2 ancestry groups. Genotyped SNPs were used to infer classical HLA alleles in the HLA-A, HLA-B, HLA-C, HLA-DQA1, HLA-DQB1 and HLA-DRB1 loci. Our data suggest that the robust HLA-B*51 association in Behçet's disease is explained by a variant located between the HLA-B and MICA genes (rs116799036: odds ratio (OR) = 3.88, P = 9.42 × 10(-50)). Three additional independent genetic associations within PSORS1C1 (rs12525170: OR = 3.01, P = 3.01 × 10(-26)), upstream of HLA-F-AS1 (rs114854070: OR = 1.95, P = 7.84 × 10(-14)) and with HLA-Cw*1602 (OR = 5.38, P = 6.07 × 10(-18)) were also identified and replicated.

It has been generally accepted that the clinical onset of familial Mediterranean fever (FMF) begins before 20 years of age in most patients. In this study, we aimed to investigate the demographic and clinical characteristics of our FMF patients with an age of onset > or =20. Records of 401 patients (female/male: 204/197) that followed up between 1990 and 1999 were reviewed according to a pre-defined protocol. All patients fulfilled the diagnostic criteria of Livneh et al. The demographic and clinical features of adult-onset FMF patients were compared to those of patients with a disease onset before 20 years of age. There were 57 patients (14%) who experienced symptoms of FMF at > or =20 years of age; 34 of them (8.5%) reported their first attack between 20 and 29 years of age; 18 of them (4.5%) between 30 and 39 years of age and five patients (1.25%) had their first attack after 40 years of age. Arthritis (42 vs. 65%, p = 0.001) and erysipelas-like erythema (7 vs. 17%, p = 0.047) were significantly less frequent in patients with adult-onset FMF compared to patients with disease onset before 20 years of age. Arthritis and erysipelas-like erythema were less frequent in adult-onset patients compared to those with an earlier disease onset. Adult-onset FMF may be a form of disease with distinct clinical, demographic and molecular characteristics. Prospective clinical studies and investigation of genotypic features are needed to identify the characteristics of this phenotypic variant.

The objective was to investigate the frequency and characteristics of tuberculosis (TB) in patients with systemic lupus erythematosus (SLE). We reviewed the charts of 556 patients with SLE who were followed up between 1978 and 2001 in our lupus clinic. Patients who developed TB after the diagnosis of SLE were identified (SLE/TB+). Ninety-six consecutive patients with SLE who did not develop TB during the follow-up were evaluated as a control group (SLE/TB-). Clinical, laboratory and management characteristics of these two groups of patients were recorded according to a predefined protocol, and compared. Of the 556 patients evaluated, 20 patients (3.6%) with TB were identified. Nine of the 20 patients (45%) had extrapulmonary TB (vertebral involvement in three patients, meningeal in two, and joint and soft tissue in four). Arthritis and renal involvement were significantly high in the SLE/TB+ group (P = 0.045, P = 0.009, respectively). The mean daily dose of prednisolone before the diagnosis of TB and the cumulative dose of prednisolone were significantly higher in the SLE/TB+ group compared to the SLE/TB- group (27 +/- 22 g versus 16 +/- 16 g, 24 +/- 45 mg versus 11 +/- 8.5 mg, respectively). In conclusion, we found an increased frequency of TB infection and a high prevalence of extrapulmonary TB in a large cohort of SLE patients. The mean daily dose of prednisolone before the diagnosis of TB and the cumulative dose of prednisolone, which possibly related to disease severity, were important determinants for the increased risk of TB in these patients with SLE.

Objective Takayasu’s arteritis is a rare large vessel vasculitis with incompletely understood etiology. We performed the first unbiased genome-wide association study (GWAS) in Takayasu’s arteritis. Methods Two independent Takayasu’s arteritis cohorts from Turkey and North America were included in our study. The Turkish cohort consisted of 559 patients and 489 controls, and the North American cohort consisted of 134 European-derived patients and 1,047 controls. Genotyping was performed using the Omni1-Quad and Omni2.5 genotyping arrays. Genotyping data were subjected to rigorous quality control measures and subsequently analyzed to discover genetic susceptibility loci for Takayasu’s arteritis. Results We identified genetic susceptibility loci for Takayasu’s arteritis with a genome-wide level of significance in IL6 (rs2069837, OR= 2.07, P= 6.70×10−9), RPS9/LILRB3 (rs11666543, OR= 1.65, P= 2.34×10−8), and an intergenic locus on chromosome 21q22 (rs2836878, OR= 1.79, P= 3.62×10−10). The genetic susceptibility locus in RPS9/LILRB3 is located within the leukocyte receptor complex (LRC) gene cluster on chromosome 19q13.4, and the disease risk variant in this locus correlates with reduced expression of multiple genes including the inhibitory leukocyte immunoglobulin-like receptor gene LILRB3 (P= 2.29×10−8). In addition, we identified candidate susceptibility genes with suggestive levels of association (P <1×10−5) including PCSK5, LILRA3, PPM1G/NRBP1, and PTK2B in Takayasu’s arteritis. Conclusion This study identified novel genetic susceptibility loci for Takayasu’s arteritis and uncovered potentially important aspects in the pathophysiology of this form of vasculitis.