Association of familial and sporadic rheumatoid arthritis with a single corticotropin-releasing hormone genomic region (8q12.3) haplotype

OBJECTIVE: Rheumatoid arthritis (RA) is a common disabling autoimmune disease with a complex genetic component. We have previously described linkage of a region of chromosome 8q12.3 with RA and association of the microsatellite marker CRHRA1 with RA in 295 affected sibling-pair families. In the current study we aimed to physically link the RA-associated marker with the corticotropin-releasing hormone (CRH) candidate gene, and to examine the genomic region for additional short tandem repeat (STR) genetic markers in order to clarify the association with RA. METHODS: We examined the association of 2 STR markers with disease in the original 295 multicase families and in a cohort of 131 simplex families to refine our understanding of this genetic region in disease susceptibility in sporadic and familial RA. Genomic library screening and sequencing were used to generate physical sequences in the CRH genomic region. Bioinformatic analysis of the sequence flanking the CRH structural gene was used to screen for additional STRs and other genetic features. Genotyping was carried out using a standard fluorescence approach. Estimations of haplotype frequencies were performed to assess linkage disequilibrium. The transmission disequilibrium test was performed using TRANSMIT. RESULTS: Physical cloning and sequencing analyses identified the genomic region linking the CRHRA1 marker and the CRH structural locus. Moreover, we identified a further STR, CRHRA2, which was in strong linkage disequilibrium with CRHRA1 (P = 4.0 x 10(-14)). A haplotype, CRHRA1*10;CRHRA2*14, was preferentially carried by unaffected parents at a frequency of 8.6% compared with the expected frequency of 3.1%. This haplotype was overtransmitted in the multiply affected families (P = 0.0077) and, similarly, in the simplex families (P = 0.024). Combined analysis of both family cohorts confirmed significant evidence for linkage (P = 4.9 x 10(-4)) and association (P = 5.5 x 10(-3)) for this haplotype with RA. CONCLUSION: In demonstrating significant linkage disequilibrium between these 2 markers, we have refined the disease-associated region to a single haplotype and confirmed the significance of this region in our understanding of the genetics of RA.     

Association study between corticotrophin-releasing hormone genomic region (8q13) and rheumatoid arthritis in the Spanish population

OBJECTIVE: To investigate whether the corticotrophin-releasing hormone (CRH) genomic region confers genetic susceptibility to rheumatoid arthritis (RA) in the Spanish population. METHODS: DNA was obtained from 121 simplex RA families and 101 healthy controls, all from Spanish origin. Two microsatellites, CRHRA1 and CRHRA2, located 25 and 20 kb downstream respectively from the CRH gene were examined using a new multiplex design. Linkage disequilibrium (LD) between the markers was assessed and association studies were carried out using the transmission disequilibrium test (TDT) implemented in TRANSMIT. RESULTS: Both markers are in Hardy-Weinberg equilibrium and there is significant LD between them in the Spanish population. Neither the polymorphic alleles of CRHRA1 and CRHRA2 markers nor their resulting haplotypes were significantly associated to RA. The associated haplotype in the UK population (CRHRA1*10; CRHRA2*14) was undertransmitted in RA patients (12 obs vs 17.43 exp), although the difference is not statistically significant (P > 0.05). CONCLUSIONS: This is the first follow-up study of the association between the CRH genomic region and RA and suggests that the CRH gene may not be involved in the pathogenesis of RA in the Spanish population. Further studies in other populations will help untangle the real contribution of this genomic region to the susceptibility to RA.     

A poly(ADP‐ribose) polymerase haplotype spanning the promoter region confers susceptibility to rheumatoid arthritis

Objective

To investigate the association of the poly(ADP‐ribose) polymerase 1 (PARP‐1) gene promoter polymorphism with rheumatoid arthritis (RA) predisposition.

Methods

An association study with 213 Spanish RA patients and 242 healthy subjects was carried out to investigate the association of all known PARP‐1 gene promoter polymorphisms, i.e., a CA microsatellite repeat, a poly(A)_n, and 3 single point mutations (C410T, C1362T, and G1672A), with disease susceptibility. Additionally, we analyzed the distribution of PARP‐1 polymorphisms in 58 Spanish families with 1 or more affected members.

Results

Upon complete genotyping of the panel of 455 samples, strong linkage disequilibrium was observed among the 5 PARP‐1 polymorphisms. Only 2 PARP‐1 haplotypes were detected: haplotype A (410T–[A]₁₀–[CA]_10–12–1362C, which includes short PARP‐1 CA alleles) and haplotype B (410C–[A]₁₁–[CA]_13–20–1362T, always paired with long PARP‐1 CA variants). Regarding the G1672A variation, although linkage disequilibrium was detected, it did not seem to be part of the conserved haplotypes described. Haplotype B was statistically overrepresented in the RA patient group compared with the healthy subjects (odds ratio 1.42, 95% confidence interval 1.06–1.91, P = 0.019). In addition, a significant dose effect of PARP‐1 haplotype carriage on disease predisposition was observed. Of note, within haplotype B, the PARP‐1 CA 97‐bp allele was found to be the RA‐predisposing marker (odds ratio 2.17, 95% confidence interval 1.27–3.72, P = 0.003, corrected P < 0.05).

Conclusion

Our results demonstrate the existence of 2 unique PARP‐1 haplotypes in the Spanish population and provide the first evidence that PARP‐1 haplotypes play a role in susceptibility to RA.

     

Association of a haplotype in the promoter region of the interferon regulatory factor 5 gene with rheumatoid arthritis

OBJECTIVE: To determine whether genetic variants of the interferon regulatory factor 5 (IRF-5) and Tyk-2 genes are associated with rheumatoid arthritis (RA). METHODS: Five single-nucleotide polymorphisms (SNPs) in IRF5 and 3 SNPs in Tyk2 were analyzed in a Swedish cohort of 1,530 patients with RA and 881 controls. A replication study was performed in a Dutch cohort of 387 patients with RA and 181 controls. All patient sera were tested for the presence of autoantibodies against cyclic citrullinated peptides (anti-CCP). RESULTS: Four of the 5 SNPs located in the 5' region of IRF5 were associated with RA, while no association was observed with the Tyk2 SNPs. The minor alleles of 3 of the IRF5 SNPs, which were in linkage disequilibrium and formed a relatively common haplotype with a frequency of approximately 0.33, appeared to confer protection against RA. Although these disease associations were seen in the entire patient group, they were mainly found in RA patients who were negative for anti-CCP. A suggestive association of IRF5 SNPs with anti-CCP-negative RA was also observed in the Dutch cohort. CONCLUSION: Given the fact that anti-CCP-negative RA differs from anti-CCP-positive RA with respect to genetic and environmental risk factor profiles, our results indicate that genetic variants of IRF5 contribute to a unique disease etiology and pathogenesis in anti-CCP-negative RA.     

Corticotropin releasing hormone (CRH) promoter polymorphisms in various ethnic groups of patients with rheumatoid arthritis

The regulatory region of the corticotropin releasing hormone (CRH) is highly conserved and plays a crucial role in the response of the organism to stress. Release of CRH initiates a cascade of events leading to the release of cortisone and the regulation of inflammatory and immune events. OBJECTIVE: Since it has been postulated that the impaired corticotropin releasing hormone (CRH) response to stress in patients with rheumatoid arthritis (RA) has a genetic basis, we investigated the distribution of CRH alleles in a cohort of UK patients as well as in South African RA patients. METHODS: Restriction fragment length polymorphism of PCR amplified DNA products of the CRH promoter. We compared the allele frequencies in the RA patients with the respective healthy control population described previously. RESULTS: As in the control populations we found two biallelic polymorphic sequences (named A1 and A2 and B1 and B2, respectively) in the CRH promoter which could be assigned to compound alleles. The A2B1 compound allele was protective against development of RA in a large group of UK Caucasoid patients (p = 0.03; odds ratio 0.43, 95% confidence interval 0.21-0.88). In contrast, A1B1 was positively associated with RA in a cohort of black South African RA patients (p = 0.05; odds ratio 1.78, 95% confidence interval 1.01-3.15). CONCLUSION: Taken together, these findings support the hypothesis that CRH promoter polymorphism represents a new genetic marker for RA susceptibility and may prove useful for the prediction of RA risk in the future when further genetic and environmental risk factors are determined.     

A comparison of clinical and immunogenetic features in familial and sporadic rheumatoid arthritis

Clinical and immunogenetic factors were compared in 214 patients with sporadic rheumatoid arthritis (RA) and 117 patients from 52 multiplex families. Sex distribution, articular disease severity and seropositivity for rheumatoid and antinuclear factors were similar in familial and sporadic disease. There was a trend for Sj?gren's and Felty's syndromes to be more frequent in familial RA but extraarticular disease features were otherwise similar in the 2 RA disease groups. Mean age of onset was 41.1 years in familial and 46.5 years in sporadic RA (p less than 0.0006); 67% of family probands, 74% of affected relatives and 57% of sporadic patients were HLA-DR4 positive (p less than 0.05 affected relatives vs sporadic). The similarity of clinical features found in familial and sporadic RA justifies the use of families with RA to study aspects of disease pathogenesis.     

A poly(ADP-ribose) polymerase haplotype spanning the promoter region confers susceptibility to rheumatoid arthritis

OBJECTIVE: To investigate the association of the poly(ADP-ribose) polymerase 1 (PARP-1) gene promoter polymorphism with rheumatoid arthritis (RA) predisposition. METHODS: An association study with 213 Spanish RA patients and 242 healthy subjects was carried out to investigate the association of all known PARP-1 gene promoter polymorphisms, i.e., a CA microsatellite repeat, a poly(A)(n), and 3 single point mutations (C410T, C1362T, and G1672A), with disease susceptibility. Additionally, we analyzed the distribution of PARP-1 polymorphisms in 58 Spanish families with 1 or more affected members. RESULTS: Upon complete genotyping of the panel of 455 samples, strong linkage disequilibrium was observed among the 5 PARP-1 polymorphisms. Only 2 PARP-1 haplotypes were detected: haplotype A (410T-[A](10)-[CA](10-12)-1362C, which includes short PARP-1 CA alleles) and haplotype B (410C-[A](11)-[CA](13-20)-1362T, always paired with long PARP-1 CA variants). Regarding the G1672A variation, although linkage disequilibrium was detected, it did not seem to be part of the conserved haplotypes described. Haplotype B was statistically overrepresented in the RA patient group compared with the healthy subjects (odds ratio 1.42, 95% confidence interval 1.06-1.91, P = 0.019). In addition, a significant dose effect of PARP-1 haplotype carriage on disease predisposition was observed. Of note, within haplotype B, the PARP-1 CA 97-bp allele was found to be the RA-predisposing marker (odds ratio 2.17, 95% confidence interval 1.27-3.72, P = 0.003, corrected P < 0.05). CONCLUSION: Our results demonstrate the existence of 2 unique PARP-1 haplotypes in the Spanish population and provide the first evidence that PARP-1 haplotypes play a role in susceptibility to RA.     

HLA-DRB1 frequency in patients with familial and sporadic rheumatoid arthritis in north east of Iran

Rheumatoid arthritis (RA) is a chronic inflammatory disease of the joints that has a strong correlation with HLA-DRB1. Family history is considered a known risk factor for RA. The aims of this study were to compare the frequency of HLA-DRB1 alleles between patients with sporadic and familial RA and also between healthy controls with RA patients (sporadic and familial) and clarify if familial RA is more severe than sporadic RA. This study included 129 consecutive patients with sporadic and 48 cases with familial (first-degree siblings) RA who visited a rheumatology unit. Demographic data, including extra-articular involvement, mean disease activity according to DAS28 (ESR) criteria, and main laboratory findings, were compared between patients with sporadic and familial RA. HLA-DRB1 typing was carried out using the PCR-SSP method, and the frequency of each allele was determined in all cases and compared with the results of HLA-DRB1 frequencies in 72 healthy controls who were previously reported by our group in northeast Iran. Patients with sporadic and familial RA were matched in age and sex, most of the cases in both groups were females. The mean age of patients was 45 years. Ocular involvement was the most frequent extra-articular manifestation of our patients. There was no significant difference between the two groups in visual analogue scale (VAS) index, number of inflamed or tender joints, extra-articular involvements, and main laboratory findings. HLA-DRB1* 01 (55 %), 04 (48 %), and 03 (43 %) alleles were the most frequent alleles in both sporadic and familial diseases. The frequency of HLA-DRB1*11 and HLA-DRB1*13 was significantly higher in normal participants compared with RA (p?=?0.001). There was no significant difference in the HLA-DRB1 allele’s frequency between sporadic and familial RA. Therefore, familial aggregation was not associated with RA severity.     

t(8;21) (q22;q22) acute myelogenous leukemia in Mexico: a single institution experience

We analyze the prevalence and clinical features of a group of patients with t(8;21) (q22;q22) acute myeloblastic leukemia, identified in a single institution in México over a 10-year period. Fifteen patients presented at the Centro de Hematología y Medicina Interna de Puebla from February 1995 to August 2005; only nine were treated and followed in the institution. Median age was 24 years, (range 7-49); there was only one male. According to the French-American-British (FAB) morphological classification of leukemia, the morphology was M2 in four cases, M4 in three cases, M3 in one case and M0 in one. In addition to the myeloid markers, lymphoid markers were identified in 6 patients. Patients were induced to remission with combined chemotherapy and three subsequently underwent bone marrow transplantation (BMT). The median overall and disease-free survival has not been reached, being above 3390 days, the probability of survival at this time was 73%. In this single-center experience in México, we found that the t(8;21) (q22;q22) variant of leukemia was more frequent than in Caucasian populations, that the co-expression of lymphoid markers in the blast cells is very frequent and that this malignancy is associated with a relatively good prognosis.     

Multipoint linkage analysis of a candidate gene locus in rheumatoid arthritis demonstrates significant evidence of linkage and association with the corticotropin-releasing hormone genomic region

OBJECTIVE: Rheumatoid arthritis (RA) is the most common disabling autoimmune disease, affecting approximately 1% of the population. The disease etiology is unknown, but it involves inflammation and immune dysregulation and is influenced by genetic variation at both HLA and other, as-yet-unidentified genetic loci. Corticotropin-releasing hormone (CRH; or corticotropin-releasing factor), a primary regulator of the hypothalamic-pituitary-adrenal axis and a key element in the response to stress and inflammation, is a strong candidate gene for RA. We examined the role of DNA variation across the region containing this gene in multicase families with RA. METHODS: We genotyped fluorescently labeled simple tandem repeat genetic markers from chromosome 8q13 in 295 families with multiple cases of RA. Singlepoint and multipoint nonparametric linkage analysis and association analysis using transmission disequilibrium testing (TDT) were also used. RESULTS: Single-point linkage analysis using a microsatellite within 30 kb of the CRH locus (CRH.PCR at position 8q13) showed a significant excess of allele sharing in 295 United Kingdom RA families with at least 2 affected members (MapMaker/Sibs logarithm of odds [LOD] 1.4; P = 5.5x10(-3); mean identity by descent [ibd] sharing 55.9%). To provide a more detailed linkage map, a multipoint analysis was conducted with an additional 7 dinucleotide microsatellite markers (average heterozygosity 0.75) flanking the CRH locus. Significant linkage was detected over a 22-cM region between D8S285 and D8S530, with the maximum singlepoint LOD score of 1.77 at D8S1723 (MapMaker/Sibs P = 2.2x10(-3); mean ibd sharing 59.3%). Multipoint analysis showed strongest evidence for linkage at the same marker (multipoint LOD 1.78, P = 2.1x10(-3), mean ibd sharing 55.8%). TDT analysis showed significant association at the CRH locus (P = 2.6x10(-3)). CRH has a sibling relative risk of 1.14, and contributes <10% to the sibling relative risk of RA. CONCLUSION: With the exception of HLA, this is the strongest evidence yet of a genetic locus that is both linked to and associated with RA, and provides an avenue for further genetic characterization and potentially novel therapeutic intervention.     

Association between tumor necrosis factor receptor II and familial,but not sporadic,rheumatoid arthritis: evidence for genetic heterogeneity

OBJECTIVE: Tumor necrosis factor alpha (TNFalpha) binds the receptors TNFRI and TNFRII. Results of genome scans have suggested that TNFR2 is a candidate rheumatoid arthritis (RA) locus. A case-control study in a UK Caucasian population has shown an association between a TNFR2 genotype (196R/R in exon 6) and familial, but not sporadic, RA. The present study was undertaken to test this association in the French Caucasian population. METHODS: To test for an association in sporadic RA, 100 families were genotyped for the 196M/R polymorphism and analyzed using the transmission disequilibrium test and haplotype relative risk. To test for an association in familial RA, RA index cases from 100 affected sibpair (ASP) families were genotyped for 196M/R. Linkage analysis was performed with 3 TNFR2 microsatellite markers. RESULTS: The TNFR2 196R/R genotype was not associated with sporadic RA (odds ratio [OR] 0.59, P = 0.72), but was associated with familial RA (OR 4.0, P = 0.026). The association was most marked in the context of TNFR2 "twin-like" RA sibs (affected sibs sharing both TNFR2 haplotypes) (OR 9.2, P = 0.0017). Linkage analysis results were consistent with the association; most of the TNFR2 linkage evidence was found in the subgroup of families with 196R/R ASP index cases. CONCLUSION: This study is the first to replicate evidence of the involvement of TNFR2 in RA genetic heterogeneity. Our data refine the initial hypothesis, to suggest that a TNFR2 recessive factor, in linkage disequilibrium with the 196R allele, plays a major role in a subset of families with multiple cases of RA.