Clinical and immunogenetic characteristics of European multicase rheumatoid arthritis families

Family history of rheumatoid arthritis: an old concept with new developments

Family history of rheumatoid arthritis (RA) is a proxy for an individual's genetic and, in part, environmental risk of developing RA, and is a well-recognized predictor of disease onset. Although family history of RA is an old concept, the degree of familial aggregation of RA, whether it differs by age, sex, or serology, and what value it has for clinical decisions once a diagnosis of RA has been made remain unclear. New data have been emerging in parallel to substantial progress made in genetic association studies. In this Review, we describe the various ways that familial aggregation has been measured, and how the findings from these studies, whether they are based on twins, cohorts of first-degree relatives, or genetic data, correspond to each other and aid understanding of the aetiology of RA. In addition, we review the potential usefulness of family history of RA from a clinical point of view, demonstrating that, in the era of big data and genomics, family history still has a role in directing clinical decision-making and research.

Paediatric celiac patients carrying the HLA-DR7-DQ2 and HLA-DR3-DQ2 haplotypes display small clinical differences

AIM

The aim of this study was to determine the relevance of HLA-DR7-DQ2 typing in a prospective cohort of paediatric coeliac disease patients from Southern Europe.

METHODS

This cross-sectional study tested 249 paediatric patients with coeliac disease. HLA-DR3-DQ2 was typed in combination with HLA-DR7-DQ2 to screen for the HLA-DQ2 haplotype. The histological, analytical and clinical characteristics of the subjects were recorded.

RESULTS

A total of 91 coeliac patients were diagnosed: 96.7% carried HLA-DQ2 and 4.4% carried HLA-DQ8. In percentage terms, 80.2% of patients carried HLA-DR3-DQ2 and 34.1% carried HLA-DR7-DQ2. We did not find significant differences between HLA-DR7-DQ2 and HLA-DR3-DQ2 paediatric patients with respect to histological damage and clinical characteristics, except for irritability and weight loss. These characteristics were more frequent in HLA-DQ2trans than in HLA-DQ2cis (22.2% vs. 0.0% [p = 0.035] and 55.6% vs. 21.4% [p = 0.017], respectively). Coeliac-specific autoantibody levels were higher in HLA-DQ2cis than one half of HLA-DQ2trans patients (105.5 vs. 19.2 U/mL, p = 0.014).

CONCLUSION

Small clinical differences were found between paediatric coeliac patients carrying HLA-DR7-DQ2 and HLA-DR3-DQ2. For a correct screening of HLA-DQ2, at least in our geographical population, the HLA-DR7-DQ2 haplotype should be typed due to its frequency and clinical presentation.

IRF5 rs2004640-T allele, the new genetic factor for systemic lupus erythematosus, is not associated with rheumatoid arthritis

BACKGROUND

Recently, a new genetic factor within the interferon regulatory factor 5 (IRF5) gene was demonstrated for systemic lupus erythematosus (SLE) through linkage and association: the rs2004640-T allele. IRF5 is involved in the production of rheumatoid arthritis (RA) cytokines, and SLE already shares with RA one genetic factor within the tyrosine phosphatase PTPN22 gene.

AIM

To test the hypothesis that the SLE IRF5 genetic factor could also be shared with RA.

PATIENTS AND METHODS

100 French Caucasian trio families with RA were genotyped and analysed with the transmission disequilibrium test, the frequency comparison of the transmitted and untransmitted alleles, and the genotype relative risk. 97% power was available to detect at least a trend in favour of a factor similar to that reported for SLE.

RESULTS

The analysis showed the absence of linkage and association globally and in "autoimmune" RA subsets, with a weak non-significant trend against the IRF5 rs20046470-T allele. Given the robustness of familial-based analysis, this slight negative trend provided strong evidence against even a weaker factor than that reported for SLE.

CONCLUSION

Our results exclude the IRF5 rs2004640-T allele as a major genetic factor for RA in this French Caucasian population.

Ethnicity may be a reason for lipid changes and high Lp(a) levels in rheumatoid arthritis

There are so many studies that suggest the changes in lipid profiles and lipoprotein (a) [Lp(a)] are associated with early atherosclerosis in rheumatoid arthritis (RA). But there are some opposite studies also. Because of marked ethnicity differences in the distribution of Lp(a), we aimed to investigate the associations of Lp(a) levels and lipid changes in Turkish RA patients. There were 30 women and 20 men, a total of 50 patients with RA (mean age 47.6 +/- 13.2 years), included and 21 healthy women and 14 healthy men (mean age 45.7 +/- 14.5 years) were recruited as a control (C) group. Serum Lp(a), total cholesterol (TC), triglyceride (TG), HDL cholesterol (HDL-C) and LDL cholesterol (LDL-C) levels were analysed for each group. Analysis of six different studies was performed. In the RA and C groups, mean serum Lp(a) levels were 39.7 +/- 64.4 and 10.5 +/- 13.4 mg/dl, respectively (P=0.001). Mean TC levels were 189.2 +/- 142.5 and 174.0 +/- 29.3 mg/dl (P=0.294), mean TG levels were 121.4 +/- 65.4 and 106.5 +/- 80.0 mg/dl (P=0.030), mean HDL-C levels were 44.5 +/- 10.0 and 47.7 +/- 4.8 mg/dl (P=0.014) and mean LDL-C levels were 94.3 +/- 35.3 and 102.0 +/- 24.6 mg/dl (P=0.98), respectively. Analysis of the six studies showed Lp(a) level was higher and HDL level was lower in RA patients than in healthy controls. Patients with RA may have altered lipid profiles from one country to another one. Especially in Turkey, higher serum Lp(a), lower HDL-C and higher TG levels may be found in RA patients instead of some findings of other countries showing different results. Ethnicity may be a reason for these findings.

Increased susceptibility to rheumatoid arthritis in Koreans heterozygous for HLA-DRB1*0405 and *0901

OBJECTIVE

To investigate the association of susceptibility and protective HLA-DRB1 alleles with rheumatoid arthritis (RA) and its clinical markers in an Asian population.

METHODS

All RA patients (n = 574) and control subjects (n = 392) were Korean. HLA-DRB1 typing and further subtyping of all alleles was performed by polymerase chain reaction, sequence-specific oligonucleotide probe hybridization, and direct DNA sequencing analysis. We used a relative predispositional effects (RPEs) method and a false discovery rate correction method for multiple comparisons.

RESULTS

The DRB1*0405 and *0901 alleles showed the most significant associations with RA (P = 7.83 x 10(-24), odds ratio [OR] 4.40 [95% confidence interval (95% CI) 3.24-5.99], and P = 3.76 x 10(-9), OR 2.47 [95% CI 1.82-3.36], respectively). The RPEs test showed that the DRB1*0401 and *0410 alleles conferred susceptibility and that the DRB1*0701, *0802, *1301, *1302, *1403, and *1405 alleles showed significant protective effects. Susceptibility and protective alleles both showed a pattern consistent with additive genetic effects, and each influenced RA independently of the other. The compound heterozygote DRB1*0405/*0901 was associated with the highest risk of RA (corrected P = 1.81 x 10(-11), OR 58.2 [95% CI 7.95-425.70]). The mean age at disease onset was approximately 4 years earlier or was 3 years earlier, respectively, in patients with at least 1 copy of the DRB1*0405 or the DRB1*0901 allele. Radiographic changes (stages II-IV) were more frequent in patients with at least 1 copy of DRB1*0405 (P = 0.032, 92.6% versus 84.3%, OR 2.33 [95% CI 1.24-4.39]).

CONCLUSION

The DRB1*0405/*0901 heterozygote has the strongest association with RA, suggesting that this heterozygote enhances the susceptibility to RA in Koreans.

Genetics in rheumatoid arthritis

This chapter reviews the latest original research on the genetics of rheumatoid arthritis (RA), with a focus on its relevance for the clinical rheumatologist. The following questions will be dealt with in order to appreciate the recent progress in this field. * Why is a knowledge of genetics useful for an understanding of the pathogenesis of RA? * Is a knowledge of genetic risk factors relevant for day-to-day clinical practice? * What methods are used for identifying genetic risk factors? * Which genetic regions have been identified in susceptibility to RA? * What risk factors have been identified? * What are the future prospects and research agenda?

Rheumatoid factors: host resistance or autoimmunity?

Rheumatoid factors (RFs), autoantibodies that bind to the Fc portion of IgG, are important in the immune response. RF-committed B-cells exist in the circulating lymphocyte pool in a high frequency (approximately 1-2 %) in normal individuals and in patients with pathological conditions associated with the sustained levels of circulating RF, such as rheumatoid arthritis (RA), Sjogren's syndrome (SS), and mixed cryoglobulinemia, associated with hepatitis C virus infection. RFs are induced by many infectious entities (viruses, bacteria, parasites) as a consequence of a secondary immune response to the pathogen, but usually the response is transient. It is likely that RFs play an important role in the host's defense against infection, both at the cellular level, where the RF B-cell can be an antigen presenting cell which can promote the antipathogen response, and at the humoral level, where RFs can contribute to the mopping up of the IgG antipathogen antibodies by contributing to immune complex formation and clearance. There has been much research on RFs in chronic pathological conditions, and the literature pertaining to their origin, structure, binding specificities, and possible roles in disease are discussed. The importance of the host defense, sometimes at the expense of an autoimmune response, is a balance that needs to be considered in light of a possible outcome of health or disease.

Genetics in rheumatoid arthritis

The data from the human genome project were published in 2001. Although this achievement will boost research in the genetics of rheumatoid arthritis (RA), most of the work is in progress. Three of the four consortia that are performing linkage studies to identify loci that are transmitted more often to patients than controls have published data on genome-wide searches in few families. Of all the possible candidate genes, the human leukocyte antigen (HLA) class II region was found in the pan-European and the US linkage studies, confirming the previous data from association studies that HLA class II alleles confer risk to RA. Although HLA as a risk factor for RA has been known for a long time, the mechanism by which HLA alleles affect disease risk are controversial. Several papers have been published recently that support the RA-protection hypothesis. Several candidate loci/genes have been suggested from association studies. However, these associations have not been reproduced by different groups in several different cohorts.

Genetics of rheumatoid arthritis: is there a scientific explanation for the human leukocyte antigen association?

Human leukocyte antigen genes associated with rheumatoid arthritis are commonly found in the unaffected population, implying that causal mechanisms of disease involve interactions between these genes and other factors. A variety of approaches-genetic, structural, and immunologic-are used to explore possible molecular interactions that may contribute to understanding the basis for this disease association. The specific relation between human leukocyte antigen-DR4 alleles and rheumatoid arthritis remains one of the strongest and most thoroughly studied examples of human leukocyte antigen risk genes among human autoimmune disorders.

Genetic approaches to the investigation of rheumatoid arthritis

The investigation of genetic factors affecting the development or severity of rheumatoid arthritis may give new insights into the pathways involved in disease pathogenesis and lead to the identification of novel therapeutic targets. Recently, several novel approaches have been used in the attempt to unravel the complex association of rheumatoid arthritis with the human leukocyte antigen ( HLA ) gene region. It is clear that non-HLA genes are also involved in disease pathogenesis, and identifying them remains a challenge. In the past year, considerable headway has been made in this field, and some interesting strategies have been used. This review summarizes the results of many of the HLA and non-HLA studies and tries to draw lessons from the investigation of genetic susceptibility factors in other complex diseases.