Functional analysis of the p53 codon 72 polymorphism in black South Africans with rheumatoid arthritis—a pilot study

Biomarkers to Predict DMARDs Efficacy and Adverse Effect in Rheumatoid Arthritis

Rheumatoid arthritis (RA), one of the most common immune system diseases, mainly affects middle-aged and elderly individuals and has a serious impact on the quality of life of patients. Pain and disability caused by RA are significant symptoms negatively affecting patients, and they are especially seen when inappropriate treatment is administered. Effective therapeutic strategies have evolved over the past few decades, with many new disease-modifying antirheumatic drugs (DMARDs) being used in the clinic. Owing to the breakthrough in the treatment of RA, the symptoms of patients who could not be treated effectively in the past few years have been relieved. However, some patients complain about symptoms that have not been reported, implying that there are still some limitations in the RA treatment and evaluation system. In recent years, biomarkers, an effective means of diagnosing and evaluating the condition of patients with RA, have gradually been used in clinical practice to evaluate the therapeutic effect of RA, which is constantly being improved for accurate application of treatment in patients with RA. In this article, we summarize a series of biomarkers that may be helpful in evaluating the therapeutic effect and improving the efficiency of clinical treatment for RA. These efforts may also encourage researchers to devote more time and resources to the study and application of biomarkers, resulting in a new evaluation system that will reduce the inappropriate use of DMARDs, as well as patients’ physical pain and financial burden.

Investigation of Caucasian rheumatoid arthritis susceptibility loci in African patients with the same disease

INTRODUCTION

The largest genetic risk to develop rheumatoid arthritis (RA) arises from a group of alleles of the HLA DRB1 locus ('shared epitope', SE). Over 30 non-HLA single nucleotide polymorphisms (SNPs) predisposing to disease have been identified in Caucasians, but they have never been investigated in West/Central Africa. We previously reported a lower prevalence of the SE in RA patients in Cameroon compared to European patients and aimed in the present study to investigate the contribution of Caucasian non-HLA RA SNPs to disease susceptibility in Black Africans.

METHODS

RA cases and controls from Cameroon were genotyped for Caucasian RA susceptibility SNPs using Sequenom MassArray technology. Genotype data were also available for 5024 UK cases and 4281 UK controls and for 119 Yoruba individuals in Ibadan, Nigeria (YRI, HapMap). A Caucasian aggregate genetic-risk score (GRS) was calculated as the sum of the weighted risk-allele counts.

RESULTS

After genotyping quality control procedures were performed, data on 28 Caucasian non-HLA susceptibility SNPs were available in 43 Cameroonian RA cases and 44 controls. The minor allele frequencies (MAF) were tightly correlated between Cameroonian controls and YRI individuals (correlation coefficient 93.8%, p = 1.7E-13), and they were pooled together. There was no correlation between MAF of UK and African controls; 13 markers differed by more than 20%. The MAF for markers at PTPN22, IL2RA, FCGR2A and IL2/IL21 was below 2% in Africans. The GRS showed a strong association with RA in the UK. However, the GRS did not predict RA in Africans (OR = 0.71, 95% CI 0.29 - 1.74, p = 0.456). Random sampling from the UK cohort showed that this difference in association is unlikely to be explained by small sample size or chance, but is statistically significant with p<0.001.

CONCLUSIONS

The MAFs of non-HLA Caucasian RA susceptibility SNPs are different between Caucasians and Africans, and several polymorphisms are barely detectable in West/Central Africa. The genetic risk of developing RA conferred by a set of 28 Caucasian susceptibility SNPs is significantly different between the UK and Africa with p<0.001. Taken together, these observations strengthen the hypothesis that the genetic architecture of RA susceptibility is different in different ethnic backgrounds.

Associations between the p53 codon 72 polymorphisms and susceptibility to systemic lupus erythematosus and rheumatoid arthritis: a meta-analysis

Objective: The aim of this study was to determine whether the p53 codon 72 polymorphism confers susceptibility to systemic lupus erythematous (SLE) and rheumatoid arthritis (RA). Methods: A meta-analysis was conducted on the associations between the p53 codon 72 polymorphism and SLE or RA using: 1) allele contrast; 2) the recessive model; 3) the dominant model; and 4) the additive model. Results: A total of 10 studies, that is, 6 SLE and 4 RA studies, involving 1578 patients and 3138 controls were considered in the meta-analysis. Meta-analysis of the p53 codon 72 polymorphism showed no association between patients and the C allele (odds ratio (OR) = 0.834, 95% confidence interval (CI) = 0.599-1.161, p = 0.282), or between SLE and the p53 C allele (OR = 0.998, 95% CI = 0.765-1.302, p = 0.989). However, stratification by ethnicity showed an association between the p53 C allele and SLE in Asians (OR = 1.410, 95% CI = 1.044-1.906, p = 0.025), but not in Europeans (OR = 0.871, 95% CI = 0.625-1.214, p = 0.415). Furthermore, an association was found between the polymorphism and SLE in Asians using recessive and additive models. However, no association was found between RA and the p53 codon 72 polymorphism in all study subjects or in Europeans. Conclusions: This meta-analysis demonstrates that the p53 codon 72 polymorphism may confer susceptibility to SLE in Asians, but not in Europeans.