Genetic variants associated with rheumatoid arthritis patients and serotypes in European populations.

OBJECTIVES: To replicate the association of rheumatoid arthritis (RA) susceptibility loci in an independent European sample and to assess their specificity with anti-citrullinated protein antibodies (ACPA) status. METHODS: A selection of 64 SNP previously associated with RA have been typed in a cohort of 267 RA patients (169 ACPA-positive and 98 ACPA-negative) and 152 controls from the Rheumatology Units of the University Hospital of Pisa (Italy) and the University of Pécs Medical Center (Hungary). Regression analyses were performed first considering overall RA patients and secondly, taking both serotype subgroups as different disease entities. The results have been adjusted for age, gender and origin of individuals. RESULTS: The well-known CD2, REL, TNFAIP3, IRF5, PTPRC, and CCR6 have been confirmed as RA disease associated loci together with recently discovered BACH2, RASGRP1, and IKZF3 loci, taking all RA patients as a unique phenotype. Results from both serological subgroups separately reflect the specificity of these susceptibility loci and show additional ACPA-positive specific associations for variants at IL6R, IL2RA, BLK, DDX6, IL6, and TLE3 genes. CONCLUSIONS: The results from GAPAID project are consistent with previously established RA disease associations for CD2, PTPRC, REL, CCR6, TNFAIP3, IRF5, BLK, IL2RA, and DDX6 loci. In addition, IL6R, BACH2, RASGRP1, TLE3, and IKZF3 are replicated for the first time in an independent European population and IL6 appears to be a suggestive new RA associated locus. The stratified analysis based on ACPA status provides further support for distinct genetic aetiologies of RA subsets, which might have therapeutic implications.

Influence of MTHFR C677T polymorphism on methotrexate monotherapy discontinuation in rheumatoid arthritis patients: results from the GAPAID European project.

OBJECTIVES: Methotrexate (MTX) is the most widely prescribed drug for rheumatoid arthritis (RA) patients, but 45% of them discontinue therapy within two years, either due to inefficacy or toxicity. Several authors have reported contradictory results related to C677T polymorphism in the MTHFR gene and response to MTX in RA. The purpose of this study was to further explore this genotype-response association in a European RA population. METHODS: This retrospective longitudinal study included a total of 269 RA patients from Italy and Hungary, of whom 73.2% had available data on MTX treatment (197 patients). C677T polymorphism (rs1801133) was genotyped by quantitative PCR using TaqMan assays. Genotype association analysis and Kaplan-Meier method were used for statistical comparisons between patients continuing and patients who abandoned MTX treatment. RESULTS: A total of 85 out of the 197 RA patients (43%) abandoned MTX treatment by the time of analysis. No significant genotype-MTX discontinuation association was found for the overall population, either at the end of the study (p=0.375), or during the follow-up (p=0.324). When the analysis was restricted to the 68 patients on MTX monotherapy, a borderline association (OR 3.15, 95% CI 0.93-10.67, p=0.057) was noted with the recessive genetic model. In agreement with that, a Kaplan-Meier analysis showed a significantly shorter time-to-discontinuation of MTX monotherapy for homozygous carriers of the T-allele (p=0.042). CONCLUSIONS: These results demonstrate that the C677T polymorphism in the MTHFR gene is involved in MTX monotherapy discontinuation in a multicentre European patient cohort, confirming previous results.

Genetic association study of systemic lupus erythematosus and disease subphenotypes in European populations.

Epidemiological studies suggest a strong contribution of genetic factors in the pathogenesis of systemic lupus erythematosus (SLE). In the last decades, many risk loci have been identified in several genetic association studies following both candidate gene and genome-wide approaches. The present work was conducted by GAPAID (Genes And Proteins for AutoImmunity Diagnostics) consortium with a dual aim: to replicate the association of several previously reported SLE susceptibility loci in an independent European sample and to explore their relation with some disease subphenotypes. A total of 48 single nucleotide polymorphisms (SNP) from 40 associated loci were typed in a cohort of 208 SLE patients and 152 controls from Rheumatology Units of the University Hospital of Pisa (Italy) and University of Pécs Medical Center (Hungary). Regression analyses were performed to detect disease susceptibility loci and to identify genes affecting specific disease manifestations (renal, neurological, or skin involvement; arthritis; secondary Sjögren syndrome; and secondary antiphospholipid syndrome). Association of previously described risk alleles from HLA locus has been replicated, while IRF5, BLK, ITGAM, and IRF8 loci have been found to be consistent with previous published results. In addition, two new subphenotype-specific associations have been detected: SNP rs5754217 (UBE2L3) with skin involvement and rs3093030 (ICAM1-ICAM4-ICAM5) with hematological disorders. Overall, results from GAPAID project are consistent with previously established associations for HLA, IRF5, BLK, ITGAM, and IRF8 SLE susceptibility loci and report for the first time two subphenotype-specific associations.

Comparative study of polymorphism frequencies of the CYP2D6, CYP3A5, CYP2C8 and IL-10 genes in Mexican and Spanish women with breast cancer.

AIM: Pharmacogenetic studies in breast cancer (BC) may predict the efficacy of tamoxifen and the toxicity of paclitaxel and capecitabine. We determined the frequency of polymorphisms in the CYP2D6 gene associated with activation of tamoxifen, and those of the genes CYP2C8, CYP3A5 and DPYD associated with toxicity of paclitaxel and capecitabine. We also included a IL-10 gene polymorphism associated with advanced tumor stage at diagnosis. PATIENTS & METHODS: Genomic DNAs from 241 BC patients from northeast Mexico were genotyped using DNA microarray technology. RESULTS: For tamoxifen processing, CYP2D6 genotyping predicted that 90.8% of patients were normal metabolizers, 4.2% ultrarapid, 2.1% intermediate and 2.9% poor metabolizers. For paclitaxel and the CYP2C8 gene, 75.3% were normal, 23.4% intermediate and 1.3% poor metabolizers. Regarding the DPYD gene, only one patient was a poor metabolizer. For the IL-10 gene, 47.1% were poor metabolizers. CONCLUSION: These results contribute valuable information towards personalizing BC chemotherapy in Mexican women.