HLA class III haplotypes in multicase rheumatoid arthritis families

Association of complement factor B allotypes and serum biomarkers in rheumatoid arthritis patients and their relatives

The aim of the study was to investigate the allotypic variability of complement factor B (BF) in patients and relatives with rheumatoid arthritis (RA) and its association with serological biomarkers and clinical features of the disease. BF allotypes were determined by high-voltage agarose gel electrophoresis in serum samples of 180 patients with RA, 198 relatives and 98 controls from Southern Brazil. Anticyclic citrullinated peptide (anti-CCP), antimutated citrullinated vimentin (anti-MCV) and IgA-rheumatoid factor (RF) were determined by ELISA and IgM-RF by latex agglutination in all samples. No significant differences were found in the allotypic variants of BF between patients with RA, relatives and controls, nor associations with gender and age of RA onset. BF*S07 allotype was significantly associated with extra-articular manifestations (EAMs; Secondary Sjögren Syndrome, pneumonitis, rheumatoid nodules) in patients with RA (P = 0.02; OR = 6.62). Patients with phenotype BF F had lower positivity for anti-MCV biomarker (P = 0.02; OR = 0.22) and those with allotype BF*S had higher prevalence of this autoantibody (P = 0.02; OR = 3.77). An increased frequency of RF-IgA was detected in relatives of patients with RA with BF FS07 phenotype (P = 0.02; OR = 7.78). Complement BF variability did not influence the development of RA in the studied patients, but BF variants may act as markers of disease prognosis, such as development of EAMs, corroborating with the role of the alternative pathway in the pathogenesis of RA.

Genomic DNA pooling for whole-genome association scans in complex disease: empirical demonstration of efficacy in rheumatoid arthritis

A pragmatic approach that balances the benefit of a whole-genome association (WGA) experiment against the cost of individual genotyping is to use pooled genomic DNA samples. We aimed to determine the feasibility of this approach in a WGA scan in rheumatoid arthritis (RA) using the validated human leucocyte antigen (HLA) and PTPN22 associations as test loci. A total of 203 269 single-nucleotide polymorphisms (SNPs) on the Affymetrix 100K GeneChip and Illumina Infinium microarrays were examined. A new approach to the estimation of allele frequencies from Affymetrix hybridization intensities was developed involving weighting for quality signals from the probe quartets. SNPs were ranked by z-scores, combined from United Kingdom and New Zealand case-control cohorts. Within a 1.7 Mb HLA region, 33 of the 257 SNPs and at PTPN22, 21 of the 45 SNPs, were ranked within the top 100 associated SNPs genome wide. Within PTPN22, individual genotyping of SNP rs1343125 within MAGI3 confirmed association and provided some evidence for association independent of the PTPN22 620W variant (P=0.03). Our results emphasize the feasibility of using genomic DNA pooling for the detection of association with complex disease susceptibility alleles. The results also underscore the importance of the HLA and PTPN22 loci in RA aetiology.

Association of complement alleles C4AQ0 and C4B5 with rheumatoid arthritis in Koreans

OBJECTIVE

To investigate the association of complement C4 allotypes with rheumatoid arthritis in Koreans.

METHODS

65 rheumatoid arthritis patients and 255 controls were typed for C4 allotypes and HLA-A, B, C, DR, and DQ antigens.

RESULTS

The frequencies of C4AQ0 (32.3% v 14.9%, P < 0.005) and C4B5 (29.2% v 12.2%, P < 0.005) were significantly increased in rheumatoid arthritis patients compared with healthy control subjects. Among rheumatoid patients, the frequency of C4AQ0 was significantly increased in both the rheumatoid factor (RF) positive (27.3%) and the RF negative (66.7%) subgroups. The frequencies of C4B5 and HLA-DR4 were significantly increased only in RF positive subgroup. C4B5 was strongly associated with HLA-DR4, whereas C4AQ0 did not show association with DR4.

CONCLUSIONS

In Koreans, C4AQ0 and C4B5 are associated with susceptibility to rheumatoid arthritis, as in the Japanese. C4B5 is strongly associated with HLA-DR4. C4AQ0 is considered to be a DR4 independent risk factor, and a disease susceptibility allele in linkage disequilibrium with C4AQ0 is suggested in Korean patients with rheumatoid arthritis.

Excess admixture proportion of extended major histocompatability complex haplotypes of Caucasian origin among rheumatoid arthritis associated haplotypes in African Americans and Afro-Caribbeans

Several extended major histocompatability complex (MHC) haplotypes are associated with susceptibility to autoimmune disease in Caucasian populations. It is known that African Americans and Afro-Caribbeans are ethnic groups descended from west, central and southern black African populations which are admixed with Caucasians. To examine the possible association of some marker of Caucasian MHC genes and susceptibility to rheumatoid arthritis (RA) in African Americans, we studied extended MHC haplotypes (HLA-B, complement and DR) in a sample of 18 African American and Afro-Caribbean probands with RA, their first degree relatives and in 15 non-RA families. We defined 36 disease-associated RA haplotypes among the probands and 96 normal haplotypes in normal individuals. To obtain the most conservative estimate, we excluded recognized Caucasian, DR4-bearing, extended MHC haplotypes from the analysis. Admixture proportions for non-HLA-DR4 extended MHC haplotypes of known Caucasian origin among RA-associated and normal haplotypes were computed (0.40 versus 0.163 respectively). When we compared the difference in proportions between RA and normal haplotypes, the proportion of extended MHC haplotypes of known Caucasian origin was significantly increased among RA-associated haplotypes (Z = 3.16, p (one sided) < 0.001, p (adjusted) < 0.008). Our results suggest that racial admixture with Caucasian MHC genes may augment RA susceptibility and thus may be one mechanism to explain the higher prevalence of RA in African Americans and Afro-Caribbeans than in black African populations.

Phenotype distribution of the third component of complement (C3) and of the properdin B factor (BF) in children with mumps meningitis

The C3 and BF phenotype frequencies were studied in children with mumps meningitis. No significant differences were found between this group and other groups; children with mumps without meningitis and healthy children.

Properdin factor B and complement factor C4 allotypes in rheumatoid arthritis: results of a follow-up study

The association between allotypes of properdin factor B (Bf), the fourth component of complement (C4A and C4B), and rheumatoid arthritis (RA), was investigated in a well-characterized cohort of RA patients who were followed from an early phase of the disease for a mean duration of 6 years. The frequencies of probable heterozygous C4AQ0 and of C4A3 were lower in RA patients compared to controls, irrespective of the presence of DR4 [relative risk (RR): 0.52 and 0.49, respectively, 95% confidence intervals (95% CI): 0.34-0.80 and 0.29-0.82]. The frequency of C4A4 was higher in RA patients compared to controls (RR: 1.86, 95% CI: 1.03-3.35), especially in DR4 positive RA patients compared to DR4 positive controls (RR: 2.58, 95% CI: 1.07-6.25), indicating a positive association of this allotype with RA additional to DR4. Bf and C4B allotypes were comparable in RA patients and controls. We did not find significant differences in Bf and C4 allotype frequencies in RA patients subdivided according to severity of the disease into a mild group and a progressive group. Because of inconsistent results in all studies on Bf and C4 allotypes, we conclude that C4 and Bf allotypes do not seem to have an important independent effect on determining disease susceptibility.

Association of rheumatoid arthritis with a dominant DR1/Dw4/Dw14 sequence motif, but not with T cell receptor beta chain gene alleles or haplotypes

HLA-DR, HLA-DQ, and T cell receptor beta (TCR beta) chain gene polymorphisms were investigated in 43 patients with rheumatoid arthritis (RA), in 10 patients with Felty's syndrome (FS), and in 5 RA multicase families. RA was found to be strongly associated with a DRB1 gene sequence motif present in DR1, DR4-Dw4, and DR4-Dw14 alleles. Ninety-three percent of RA patients were positive for at least 1 of these alleles, providing strong support for the "shared epitope hypothesis." The frequency distribution of this sequence motif suggests a dominant mode of inheritance. All 10 FS patients were DR4-Dw4 positive. Different DR-DQ associations among DR4 positive RA and FS patients indicate heterogeneity in the genetic susceptibility to these 2 disease entities. Furthermore, analyses of TCR V beta 8, V beta 11, and C beta gene polymorphisms did not support the notion of an influence of TCR beta germline allotypes on RA susceptibility.

Polymorphism of major histocompatibility complex extended haplotypes bearing HLA-DR3 in patients with rheumatoid arthritis with gold induced thrombocytopenia or proteinuria

The distribution of DR3 and of extended haplotypes bearing DR3 was studied in three groups of subjects: 35 patients with rheumatoid arthritis (RA) with gold induced thrombocytopenia or proteinuria, 185 patients with RA without these side effects, and 300 normal healthy controls. The extended haplotypes bearing DR3 were analysed with cDNA probes for DR alpha, DR beta, DQ alpha, and DQ beta genes. The data showed that the prevalence of DR3 was significantly higher in patients who developed gold induced thrombocytopenia or proteinuria than in normal controls or patients with RA without these side effects. Distribution of three extended haplotypes bearing DR3 (B8, DR3; B18,DR3; non-B8,non-B18,DR3) in patients with RA with thrombocytopenia or proteinuria was significantly different from that in normal controls, but not from that in patients with RA without these toxic reactions. Southern blot analysis of DR, DQ genes with cDNA probes showed that the extended haplotype bearing B8,DR3, which carries DQA2.1 and DQB2.1 genes, was present in a significantly higher proportion of patients with RA with gold induced thrombocytopenia or proteinuria (22/24, 92%) than in patients with RA without these side effects (32/45, 71%) or normal subjects (40/61, 66%). The data suggest that the genomic region on chromosome 6 involved in susceptibility to gold induced thrombocytopenia or proteinuria should be extended to the DQA2, DQB2 gene loci.

HLA-DR4 associated Dw types in rheumatoid arthritis

Frequencies of HLA-DR4 and its related Dw types were compared between randomly selected normal controls and the index cases of multiplex rheumatoid arthritis (RA) families. A DR4 frequency of 68.3% was observed in index cases (n = 57) compared to 31.2% in normal controls (n = 96). Cellular typing with homozygous typing cells (HTCs) revealed significant increases of Dw4 (49.1% vs 22.9% RR = 3.2 p less than 0.001) and Dw14 (22.8% vs 2.1% RR = 13.9 p less than 0.001) in the index cases. A non-significant increase was seen for Dw13 (8.8% vs 4.1%). When DR4 positive patients and controls were compared, a significant increase was seen only for Dw14 (34.2% vs 6.6% RR = 7.3 p less than 0.01). Data from HLA genotyped RA and normal families allowed an examination of haplotype combinations of HLA-B antigens and DR4/Dw types to be made. HLA-Dw4 was predominantly found with B44 and Bw62 with nearly all DR4/Bw62 haplotypes being Dw4 positive. HLA-Dw13 was associated with B44 and Dw14 with Bw60, B44 and B27. Based on HTC and normal family data. Dw10 was found to be strongly associated with B38 containing haplotypes. Analysis of 69 C4A, C4B complement typed DR4 haplotypes failed to show any statistically significant association between Dw type and "complotype". However, there was a suggestion of C4A3. BQO being associated with Dw4 (34.2% vs 16.1% X2 = 2.9 p = ns) and C4A3, B1 with Dw14 (45.5% vs 27.6% X2 = 2.1 p = ns).(ABSTRACT TRUNCATED AT 250 WORDS)