No relationship of −627 interleukin-10 promoter polymorphism in Chinese patients with rheumatoid arthritis

Abstrtact The aim of this study was to examine whether –627 interleukin-10 (IL-10) promoter polymorphism is a marker of susceptibility to or severity of rheumatoid arthritis (RA) in Chinese patients in Taiwan. The study included 198 Chinese patients with RA. One hundred unrelated healthy individuals living in central Taiwan served as the control subjects. The relationship between IL-10 gene polymorphism and clinical manifestations of RA was evaluated. For the genotype, allelic frequency, and carriage rate of IL-10 polymorphism, there were no statistically significant differences found between patients and controls. Furthermore, we did not detect any association of IL-10 genotype with rheumatoid factor (RF), extra-articular involvement, or bone erosion in the RA patients. The lack of association of –627 IL-10 gene polymorphism with RA and the clinical findings in our study implies that the IL-10 gene polymorphism cannot serve as a candidate gene marker for screening RA patients.     

Tumor necrosis factor alpha, its soluble receptor I, and -308 gene promoter polymorphism in patients with rheumatoid arthritis with or without amyloidosis: implications for the pathogenesis of nephropathy and anemia of chronic disease in reactive amyloidosis

OBJECTIVE: To study tumor necrosis factor alpha (TNFalpha) -308 gene promoter polymorphism and circulating levels of TNFalpha and soluble TNF receptor type I (sTNFRI) in rheumatoid arthritis (RA) patients with and without reactive amyloidosis. METHODS: In a retrospective study, we examined 55 RA patients with biopsy-proven reactive amyloidosis and 55 control RA patients without amyloidosis (matched for age, sex, rheumatoid factor titer, and RA duration). Inflammatory activity was assessed by measuring the erythrocyte sedimentation rate and C-reactive protein level. TNFalpha gene promoter polymorphism was studied using polymerase chain reaction-restriction fragment length polymorphism assay. Cytokine and receptor levels were measured by enzyme-linked immunoassays. RESULTS: Patients with RA and amyloidosis had significantly higher TNFalpha and sTNFRI levels than did the control RA patients. The increased circulating levels of TNFalpha correlated with interleukin-18 levels, but not with the serum amyloid A protein levels or with TNFalpha -308 gene promoter polymorphism (reported to be associated with high TNFalpha levels and certain disease susceptibilities). In the patients with RA and amyloidosis, those with anemia had significantly higher TNFalpha and sTNFRI levels than did those without anemia, and circulating TNFalpha and sTNFRI levels correlated negatively with hemoglobin concentrations. In the patients with RA and amyloidosis, those with nephropathy had significantly higher TNFalpha and sTNFRI levels than did those without nephropathy; in patients with isolated proteinuria (but no creatinine elevation) the TNFalpha level was also significantly increased, indicating that the TNFalpha elevation was not merely a consequence of impaired renal function. CONCLUSION: This study shows that circulating levels of TNFalpha and sTNFRI are significantly increased in RA patients with amyloidosis as compared with control RA patients without amyloidosis and that the increased levels may be implicated in the pathogenesis of certain disease manifestations, including anemia of chronic disease and renal pathology in reactive amyloidosis.     

Tumor necrosis factor promoter polymorphisms in patients with rheumatoid arthritis in Taiwan

OBJECTIVE: To investigate the association of tumor necrosis factor (TNF) promoter polymorphisms with rheumatoid arthritis (RA) in Taiwan. METHODS: TNF promoter polymorphisms at positions -238, -244, -308, -376, -857, and -863 were determined in 97 patients with RA and 97 healthy controls using the PCR-RFLP method. RESULTS: The phenotypic frequency of TNF-308A was significantly lower in patients with RA than in healthy controls. This finding can only be found in HLA-DR4 negative patients, not in DR4 positive RA patients and controls. The TNF promoter polymorphisms at positions -238, -244, -308, -376, -857, and -863 were not related to the clinical manifestations of RA patients. CONCLUSION: TNF-308A itself or a neighboring gene may be a protective factor for the development of RA in the HLA-DR4 negative population in Taiwan. TNF promoter polymorphisms were not associated with the clinical manifestations of patients with RA in Taiwan.     

Tumour necrosis factor a −308 promoter polymorphism in patients with rheumatoid arthritis

There are controversial reports that TNF-a promoter polymorphism may be an independent marker of susceptibility to rheumatoid arthritis (RA). We used Polymerase chain reaction amplification and Restriction fragment length polymorphism for analysis of the polymorphism at position -308 in promoter of TNF-α gene in 34 patients with RA and 30 healthy individuals. Distribution of TNF-genotypes in RA patients did not differ from that in controls. Moreover, there was apparent association between the -308 TNF-α polymorphism and erosions in hand x-Ray was found (P value = 0.043). We suggest that TNF-α -308 promoter polymorphism is not a genetic risk factor for RA susceptibility but may be associated with radiographic damage in rheumatoid patients. All work was funded by the Chancellor for Research of Mashhad University of Medical Science.     

Tumor necrosis factor-alpha and Interleukin-10 gene promoter polymorphisms in Turkish rheumatoid arthritis patients

Tumor necrosis factor and interleukin 10 have been implicated in the pathogenesis of rheumatoid arthritis (RA). Certain single-nucleotide polymorphisms (SNPs) within the promoter region of the IL-10 and TNF genes have been associated with altered levels of circulating IL10 and TNF. We aimed to explore the association of IL-10 and TNF-alpha polymorphisms in Turkish RA patients. We analyzed the association of TNF-alpha (-308G/A, -238G/A, -376G/A) and IL10 (-1082G/A, -819C/T, -592C/A) polymorphisms in 98 Turkish patients with rheumatoid arthritis and 122 healthy subjects using ARMS-PCR. The correlation of these findings with RF positivity and erosive disease in RA patients was also sought. A significant association was found between having RA and -1082 G allele (p = 0.008; OR = 1.44, 95% CI 1.11-1.86). There was no association between RA and -819C/T polymorphism. Significant differences were observed in IL10 GCC and ACC haplotypes distribution between RA and control subjects (p = 0.006; OR = 1.46, 95% CI 1.13-1.89 and p = 0.011; OR = 1.43, 95% CI 1.09-1.88, respectively). No statistically significant association was found between TNF-alpha 308G/A, -238G/A, -376G/A polymorphisms and RA. No significant association was found between RF positivity and erosive disease and TNF-alpha, IL10 gene polymorphisms. In addition, when combined genotypes were analyzed, no significant difference was found between RA patients and healthy controls. Our findings suggest that IL-10 1082 G/A polymorphism or GCC, ACC haplotypes may be associated with RA in Turkish patients.     

Genetic contribution of the CD14 -159C/T dimorphism in the promoter region in Japanese RA

OBJECTIVE: To study the contribution of the CD14 gene to the pathogenesis of rheumatoid arthritis (RA) in Japanese patients. METHODS: CD14 genotyping was carried out at the -159C/T dimorphic site in 97 RA patients and 104 normal subjects by the PCR-RFLP (restriction fragment length polymorphism) METHOD: HLA-DRB1 genotyping was performed by the PCR-SSCP (sequence specific conformational polymorphism) method. RESULTS: The -159C/T dimorphism is not associated with whole RA or with female RA, and the results were compatible with a previous report from Germany. The -159C/T dimorphism was not associated with rheumatoid factor (RF)-positive RA, although the -159T allele tended to be associated with RF in the German report. The -159C/T dimorphism showed no association even in RA patients with the RA-susceptibility HLA-DRB1*0405. The -159T allele was prevalent in Japanese controls. CONCLUSION: The CD14 gene is very unlikely to be genetically involved in the pathogenesis of Japanese RA.     

TNFalpha-308A allele in juvenile dermatomyositis: association with increased production of tumor necrosis factor alpha, disease duration, and pathologic calcifications

OBJECTIVE: To characterize the association between the TNFalpha-308A allele and 1) duration of active disease, 2) peripheral blood mononuclear cell (PBMC) synthesis of tumor necrosis factor alpha (TNFalpha) in vitro, and 3) pathologic calcifications in patients with juvenile dermatomyositis (DM). METHODS: The TNFalpha-308 alleles were determined by polymerase chain reaction in 37 white patients with juvenile DM and in 29 control subjects. Patients were grouped according to duration of immunosuppressive therapy: long (> or =36 months) or short (<36 months). Unstimulated PBMC were examined by enzyme-linked immunosorbent assay for TNFalpha production in vitro. Sixty-five white patients with juvenile DM were examined for pathologic calcifications. RESULTS: TNFalpha-308A was identified in 18 of 37 patients with juvenile DM, in contrast with 5 of 29 controls (P = 0.009). Sixteen of the 18 patients with juvenile DM who had the TNFalpha-308A allele had a disease course > or =36 months, compared with 6 of 19 patients with TNFalpha-308G (P = 0.001). PBMC from 16 of the 18 juvenile DM patients with TNFalpha-308A synthesized more TNFalpha (median 53 pg/ml) compared with PBMC from 9 of 19 patients with TNFalpha-308G (median 19 pg/ml) (P = 0.007). Nineteen of 22 juvenile DM patients requiring therapy for > or =36 months produced more TNFalpha (median 20.5 pg/ml) in comparison with 6 of 15 juvenile DM patients with a <36-month treatment course (median TNFalpha 0.0 pg/ml) (P = 0.005). Detectable calcifications were present in 3 of 8 children with juvenile DM who had TNFalpha-308AA, compared with 2 of 21 children with TNFalpha-308AG and 1 of 36 children who had TNFalpha-308GG (P = 0.017). CONCLUSION: A long course of juvenile DM and the presence of pathologic calcifications were associated with the TNFalpha-308A allele and with the increased production of TNFalpha, which may perpetuate the inflammatory response.     

MHC2TA promoter polymorphism (-168*G/A, rs3087456) is not associated with susceptibility to rheumatoid arthritis in British Caucasian rheumatoid arthritis patients

OBJECTIVE: To investigate the association of a single-nucleotide polymorphism (SNP) in the promoter region of MHC2TA gene (-168*G/A, rs3087456), which has previously been described in a Swedish rheumatoid arthritis (RA) cohort, in British Caucasian RA patients. METHODS: We genotyped 733 RA patients and 613 healthy controls for MHC2TA -168*G/A SNP by amplification-refractory mutation system (ARMS). Data were analysed using SPSS version 13.0 software and the chi-square test was applied where appropriate. RESULTS: The MHC2TA -168*G/A SNP was not associated with increased susceptibility to RA in our patients. Stratifying the patients according to the presence or absence of rheumatoid factor (RF) showed the SNP to be more common in RF negative patients, but this did not reach statistical significance. CONCLUSION: We did not confirm the previously reported association of this MHC2TA polymorphism with RA in our UK population despite its ethnic similarities with the Swedish population in which it was first described.     

Can tumor necrosis factor receptor II gene 676T>G polymorphism predict the response grading to anti-TNFα therapy in rheumatoid arthritis?

In this study we analyzed whether the polymorphisms 676T>G in the tumor necrosis factor receptor (TNFR) II gene and -308G>A in the TNFalpha promoter gene may influence the response grading to anti-TNFalpha therapy in rheumatoid arthritis. We enrolled and genotyped 105 RA patients treated with etanercept (n = 55), infliximab (n = 40) and adalimumab (n = 10) for 1 year. The clinical response was evaluated according to the ACR criteria every 3 months. Patients with TNFRII 676TG genotype was significantly associated with lower ACR response compared with 676TT genotype, at 3 (OR 3.78 95% CI 1.07-13.31) and 12 months (OR 4.30 95% CI 1.16-15.99) of treatment. No significant association between TNFalpha -308G>A polymorphism and the clinical response was found. TNFRII 676TG genotype is associated with a lower response to anti-TNFalpha therapy, independently from the specific agent used. This polymorphism could become a useful genetic marker for predicting the different response grading to anti-TNFalpha therapy.     

Association between urokinase gene 3'-UTR T/C polymorphism and Chinese patients with rheumatoid arthritis in Taiwan

OBJECTIVES: The purpose of this study was to investigate whether the urokinase gene 3'-UTR C/T polymorphism is a marker of susceptibility to or severity of rheumatoid arthritis (RA) in Chinese patients. METHODS: A total of 145 RA patients and 134 healthy control subjects were enrolled in this study. We identified the C/T polymorphism of the urokinase gene, which is mapped on the 3'-untranslated region (3'-UTR) on chromosome 10 by polymerase chain reaction (PCR). RESULTS: There were significant differences in the distribution of the urokinase gene 3'-UTR C/T polymorphism frequency between RA patients and subjects in the control group. However, we did not detect an, association between the urokinase gene 3'-UTR C/T polymorphism and rheumatoid factor (RF), extraarticular involvement or bone erosion in RA patients. CONCLUSION: The urokinase gene 3'-UTR "T" allele was associated with RA in Chinese patients in Taiwan.     

The -308 polymorphism in the tumour necrosis factor (TNF) gene promoter region and ex vivo lipopolysaccharide-induced TNF expression and cytotoxic activity in Chilean patients with rheumatoid arthritis

OBJECTIVE: To investigate the association of the -308 polymorphism in the promoter region of the tumour necrosis factor (TNF) gene with susceptibility to the development of RA. We also explored the expression and cytotoxicity of TNF in relation to the -308 polymorphism. METHODS: We recruited 92 RA patients and 42 healthy control subjects. Genotyping for the TNF promoter was performed by polymerase chain reaction-restriction fragment length polymorphism analysis. To study the overexpression of TNF we used a whole-blood culture system. TNF cytotoxicity was assessed in the L929 cell line. RESULTS: The TNF2 allele was found in 23% of RA patients and 10% of controls. Although both groups showed high variability in serum TNF concentration, in the lipopolysaccharide-induced TNF level and in the cytotoxicity of the cytokine in the L929 cell line, these differences were not associated with the -308 TNF polymorphism. CONCLUSION: No associations were found between the -308 TNF promoter polymorphism, serum and ex vivo TNF levels and the cytotoxic activity of TNF in RA patients.     

Association between the level of circulating bioactive tumor necrosis factor alpha and the tumor necrosis factor alpha gene polymorphism at -308 in patients with rheumatoid arthritis treated with a tumor necrosis factor alpha inhibitor

OBJECTIVE: The tumor necrosis factor alpha (TNFalpha) -308A polymorphism has been associated with high production of TNFalpha and poor response to anti-TNFalpha therapy, but these associations remain controversial. The aim of this study was to explore the association between circulating TNFalpha bioactivity, the TNFalpha -308 polymorphism, and the clinical response to infliximab in patients with rheumatoid arthritis (RA). METHODS: One hundred ninety-eight patients with RA were treated with infliximab and methotrexate. Responses at 6 months according to the American College of Rheumatology (ACR) preliminary criteria for improvement in RA were recorded. Genotyping for the TNFalpha -308 polymorphism was performed by enzyme-linked oligosorbent assay. Circulating TNFalpha bioactivity was evaluated in 50 patients with RA by assessing the production of interleukin-6 (IL-6) in synoviocytes induced by a small amount of TNFalpha plus plasma. IL-6 production in 48-hour supernatants and the levels of TNFalpha protein and IL-6 were measured by enzyme-linked immunosorbent assay. RESULTS: The TNFalpha -308 polymorphism was not associated with the ACR response to infliximab. The level of circulating TNFalpha bioactivity was higher in patients with the TNFalpha -308 A/A or A/G genotype than that in patients with the G/G genotype (median 50.0 ng/ml [interquartile range (IQR) 31.5-62.0] versus 33.0 ng/ml [IQR 16.5-47.5]; P < 0.02). However, no difference was observed for the TNFalpha protein level according to genotype (median 0.62 pg/ml [IQR 0.00-8.85] for G/G versus 3.35 pg/ml [IQR 1.55-4.63] for A/A or A/G; P not significant). The level of circulating TNFalpha bioactivity was higher in good responders (> or =50% improvement) than in poor responders (< or =20% improvement) (median 45.0 ng/ml [IQR 21.0-59.0] versus 28.0 ng/ml [IQR 14.0-39.0]; P = 0.05). However, the level of TNFalpha protein was similar in both groups. CONCLUSION: The level of functional circulating TNFalpha is partially genetically determined and is predictive of the clinical response to infliximab. Nonresponders to anti-TNFalpha therapy are likely to have a disease that is not primarily driven by TNFalpha.     

Polymorphism at position -308 of the tumor necrosis factor alpha gene influences outcome of infliximab therapy in rheumatoid arthritis

OBJECTIVE: To test whether the G-to-A polymorphism at position -308 in the promoter of the tumor necrosis factor alpha (TNFalpha) gene influences response to infliximab therapy in patients with rheumatoid arthritis (RA). METHODS: We genotyped 59 RA patients by polymerase chain reaction and subdivided them into two groups: those with the A/A or A/G genotype and those with the G/G genotype. We compared the groups' clinical responses to infliximab treatment after 22 weeks, using the Disease Activity Score in 28 joints (DAS28). RESULTS: We found that 42% of patients in the A/A and A/G group and 81% of patients in the G/G group had improvement of at least 1.2 in the DAS28 score (P = 0.0086). The average improvement in the DAS28 score was 1.24 in the A/A and A/G patients and 2.29 in the G/G patients (P = 0.029). CONCLUSION: These data suggest that patients with a TNFalpha -308G/G genotype are better infliximab responders than are patients with A/A or A/G genotypes. TNFalpha -308 genotyping may be a useful tool for predicting response to infliximab treatment.     

Lack of association between TNFalpha gene polymorphism at position -308 and risk of acute rheumatic fever in Turkish patients

OBJECTIVE: Acute rheumatic fever (ARF) is a multisystem inflammatory disease process that follows nasopharyngeal infection caused by group A streptococcus (GAS) (Streptococcus pyogenes). Recent studies have demonstrated that allelic variations at the tumour necrosis factor alpha (TNFalpha) locus are involved in the nature of rheumatic diseases such as juvenile idiopathic arthritis and rheumatic heart disease. Thus, TNFalpha polymorphisms at -308 in ARF patients might be useful in contributing to identification of the primary factors associated with pathogenesis of ARF. METHODS: We performed a case-control association study between the common G/A promoter polymorphism at position -308 in the TNFalpha gene and ARF in Turkish patients, investigating whether this locus acts as a risk factor or has a modifying effect. RESULTS AND CONCLUSION: Previous studies have reported that TNFalpha plays a major role in the pathogenesis of a number of autoimmune and inflammatory diseases. Moreover, significantly elevated TNFalpha levels were reported in patients with ARF. However, in our sample of patients with ARF (n = 66), no such association was found. No interactive effect was found between the TNFalpha polymorphism at position -308 and no association was detected with disease progression. These findings suggest that the role of TNFalpha in ARF may be in linkage disequilibrium with some other severity genes not yet genetically determined.     

TNF-alpha -308 promoter polymorphism in patients with rheumatoid arthritis

OBJECTIVES: Rheumatoid arthritis (RA) is a chronic inflammatory disease in which tumour necrosis factor-alpha (TNF-alpha) plays an important role. There are, however, controversial reports that TNF-alpha promoter polymorphism may be an independent marker of susceptibility and severity of RA. The aim of the present study was to examine the TNF-alpha -308 promoter polymorphism in patients with RA. METHODS: We examined 91 patients with RA diagnosed according to the criteria of the American College of Rheumatology. Polymerase chain reaction (PCR) amplification was used for analysis of the polymorphism at position -308 in promoter of TNF-alpha gene. RESULTS: Distribution of TNF-alpha genotypes in RA patients did not differ from that in control subjects. Moreover, there was no association between TNF-alpha genotypes and age at disease diagnosis, disease activity in global physician's assessment, and joint and extra-articular involvement. There was also no correlation between TNF-alpha polymorphism and disease activity measures, including erythrocyte sedimentation rate (ESR), CRP, number of swollen and tender joints, and morning stiffness duration. CONCLUSIONS: We suggest that TNF-alpha -308 promoter polymorphism is not a genetic risk factor for RA susceptibility and severity.     

Positive relationship between melatonin receptor type 1B polymorphism and rheumatoid factor in rheumatoid arthritis patients in the Korean population

Melatonin is reported to be an anti-inflammatory agent. No genetic study concerning the association between melatonin and inflammatory disease has yet been reported. Here we performed a polymorphism study on the melatonin receptor type 1B (MTNR1B) in Korean rheumatoid arthritis (RA) patients and controls. The polymorphism of MTNR1B located in 3'-untranslated region (rs 1562444) was selected for its higher rate of heterozygosity among other single nucleotide polymorphisms (SNPs) in both MTNR1A and MTNR1B genes and investigated in RA patients (n = 173) and healthy controls (n = 195) by polymerase chain reaction-restriction fragment length polymorphism assay using NlaIII restriction enzyme. No statistically significant difference in either genotype distribution or allele frequency was observed between RA patients and controls. The genotype distributions and allele frequencies of rheumatoid factor negative [RF(-)] patients were similar to those of controls. However, statistical analysis of genotype revealed a significant association (chi2 = 6.42, P = 0.04) is present between RF(+) and MTNR1B SNP (rs 1562444). Although no statistically significant difference in allele frequency between RF(+) and controls was observed (chi2 = 2.75, P = 0.10), the results might suggest that MTNR1B SNP (rs 1562444) is associated with the presence of RF in RA. This is the first study, to our knowledge, to report a positive genetic relationship between melatonin and RA.     

Association of the PD-1.3A allele of the PDCD1 gene in patients with rheumatoid arthritis negative for rheumatoid factor and the shared epitope

OBJECTIVE: To study the frequency of allele A of polymorphism PD-1.3 of the PDCD1 gene in patients with rheumatoid arthritis (RA) and its subsets, based on the presence of rheumatoid factor (RF) and the shared epitope (SE) alleles. METHODS: A total of 1,175 patients with RA and 3,404 controls were genotyped for the PD-1.3 A/G polymorphism, which previously was identified as being involved in susceptibility to systemic lupus erythematosus (SLE) in patients of European descent. RESULTS: We first detected a trend for association of allele A of the single-nucleotide polymorphism PD-1.3 with RA (P = 0.053, odds ratio [OR] 1.18, 95% confidence interval [95% CI] 0.99-1.41). To further clarify the nature of this association, patients with RA were divided into 4 groups according to the presence of RF and the SE alleles. Association was found only in the group of patients negative for both RF and the SE alleles (P = 0.0054 [corrected P = 0.015], OR 1.75, 95% CI 1.15-2.65). CONCLUSION: Patients negative for both RF and the SE alleles showed association with the same allele that we previously identified as being involved in susceptibility to SLE. These results provide the first evidence of the involvement of the human PDCD1 gene in arthritis.     

Tumour necrosis factor (TNF)alpha -308 G/G promoter polymorphism and TNFalpha levels correlate with a better response to adalimumab in patients with rheumatoid arthritis

OBJECTIVE: To investigate the influence of -308 tumour necrosis factor-alpha (TNFalpha) promoter polymorphism and circulating TNFalpha levels in the clinical response to adalimumab treatment in patients with rheumatoid arthritis (RA). METHODS: Eighty-one patients with active RA were genotyped for the -308 TNFalpha polymorphism by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis and subdivided into two groups for each polymorphism (G/A and G/G genotype). All received 40 mg of adalimumab subcutaneously every other week. We compared the groups' clinical responses to adalimumab at 8, 16, and 24 weeks using the Disease Activity Score in 28 joints (DAS28). RESULTS: Both groups showed a significant improvement from baseline. A significant difference between groups was found at week 24. We found that 88.2% of G/G versus 68.4% of G/A for the -308 polymorphism were DAS28 responders (p = 0.05). The score improvement at week 24 was 2.5 +/- 1.3 in the G/G group and 1.8 +/- 1.3 in the G/A group for the -308 polymorphism (p = 0.04). The median of serum TNFalpha levels of the G/A group were lower than those of the G/G group, and statistically different at weeks 8 and 24 (p < 0.039 and p < 0.043). When comparing baseline levels to those achieved at 8, 16, and 24 weeks for the whole group, only responder patients showed a statistically significant overall increase in TNFalpha over time (p < 0.000001). CONCLUSION: A relationship between DAS28 improvement, the -308 G/G polymorphism, and increased circulating TNFalpha levels was found in Chilean RA patients treated with adalimumab.     

Tumour necrosis factor microsatellites and HLA-DRB1*, HLA-DQA1*, and HLA-DQB1* alleles in Peruvian patients with rheumatoid arthritis

OBJECTIVE: To study the association between rheumatoid arthritis (RA) and HLA and tumour necrosis factor (TNF) polymorphism in Peruvian mestizo patients in comparison with ethnically similar controls. METHODS: Seventy nine patients with RA and 65 ethnically matched healthy controls were genotyped for HLA-DRB1, HLA-DQA1, HLA-DQB1, and TNFalpha and TNFbeta alleles using PCR amplification. Clinical severity was assessed as mild, moderate, or severe in 35 of the patients. RESULTS: TNFalpha6 showed the strongest association with disease susceptibility. The TNFalpha6 allele was more common in patients than in controls (p<0.0076) and the proportion of patients with at least one copy of this allele was greater (p<0.015, relative risk 2.35). Among the HLA-DRB1* alleles with the shared epitope sequence, only the DRB1*1402 allele was significantly increased in patients compared with controls (p<0.0311), as was the proportion of patients with at least one copy of this allele (p<0.0232, relative risk 2.74). In contrast, the overall frequency of alleles with the shared epitope was not different in patients and controls. The haplotype HLA-DRB1*1402-DQB1*0301-DQA1*0401 was significantly more common in patients. TNFalpha6 was more common in patients whether or not they had this haplotype. None of the 11 patients lacking the TNFalpha6 allele had severe disease. CONCLUSIONS: This study shows for the first time that TNF gene polymorphism is associated with susceptibility to RA in a non-white population. TNFalpha6 and HLA-DRB1*1402 independently conferred significantly increased risk in Peruvian mestizo patients.