Polymorphisms in chromosome region 12q13 and their influence on age at onset of type 1 diabetes.

AIMS/HYPOTHESIS: A complex region covering numerous genes in 12q13 was first associated with type 1 diabetes in the Wellcome Trust Case-Control Consortium (WTCCC) study. Two studies performed in a white population have tested the association of polymorphisms within this region with age at onset of the disease, with seemingly contradictory results. We aimed at replicating three of the strongest signals in a group of patients with early and late disease onset. METHODS: Polymorphisms rs773107, rs2292239 and rs10876864 were genotyped in 444 type 1 diabetic Spanish participants (age at onset 0-65 years) and 861 controls. The influence of single nucleotide polymorphisms (SNPs) on age at onset was tested through stratified and continuous analyses. RESULTS: rs773107 and rs2292239 were significantly associated with the disease, while rs10876864 showed a trend towards statistical significance in the whole population analyses. Comparison of early-onset patients to controls was significant for the three polymorphisms (allelic p < 0.006). Late-onset patients and controls did not reveal statistical differences. Analysis of age at onset in both rs773107 and rs2292239 showed differences between genotypes (p ≤ 0.002), alleles (p ≤ 0.013) and homozygotes for the risk genotype (p ≤ 4 × 10(-4)). Polymorphism rs10876864 showed trends towards statistical significance in the allelic frequencies (p = 0.051) and homozygotes for the risk genotype (p = 0.056). Subjects with risk genotypes had a disease onset between 2 and 5 years earlier than carriers of protective alleles. CONCLUSIONS/INTERPRETATION: We replicate two of the previously studied associations in a Spanish population and find new evidence of the influence of the 12q13 region on age at onset of type 1 diabetes.

The R30Q DLG5 variant is not associated with celiac disease or inflammatory bowel disease in the Spanish population.

Alterations in intestinal epithelial permeability could underlie inflammatory bowel disease (IBD) and celiac disease (CeD) etiology, as supported by previous association studies. One related gene, DLG5 [discs, large homologue 5 (Drosophila)], has been associated with IBD in several populations and with CeD in the Dutch population. We tried to confirm the involvement of DLG5 in CeD performing a case-control study (725 CeD patients and 803 controls) by analysing the R30Q variant (rs1248696). Genetic frequencies did not significantly differ between groups (P > 0.80) and the meta-analysis with the Dutch data did not show any association. Additionally, we evaluated the effect of R30Q in IBD risk (858 patients), as discordant results were previously obtained. No association was detected. Our study does not support the effect of the R30Q DLG5 variant in CeD or IBD predisposition in the Spanish population.

Members 6B and 14 of the TNF receptor superfamily in multiple sclerosis predisposition.

TNFRSF6B and TNFRSF14 genes were recently associated with Crohn's disease and rheumatoid arthritis. TNFRSF14 is known as herpes virus entry mediator (HVEM), and herpes viruses have been involved in the aetiology of multiple sclerosis (MS). MS patients present human herpes virus 6 (HHV6) in active plaques and increased antibody responses to HHV6. We aimed to ascertain the role of these genes in MS susceptibility and to investigate the relationship of the gene encoding the widely expressed HVEM receptor with the active replication of HHV6 found in some MS patients. Genotyping of 1370 Spanish MS patients and 1715 ethnically matched controls was performed. HHV6A DNA levels (surrogate of active viral replication) were analysed in serum of MS patients during a 2-year follow-up. Both polymorphisms were associated with MS predisposition, with stronger effect in patients with HHV6 active replication-TNFRSF6B-rs4809330(*)A: P=0.028, OR=1.13; TNFRSF14-rs6684865(*)A: overall P=0.0008, OR=1.2; and HHV6-positive patients vs controls: P=0.017, OR=1.69.

Association between idiopathic achalasia and IL23R gene.

BACKGROUND: Idiopathic achalasia is a primary esophageal motor disorder of unknown etiology. Different evidences have been reported in support of achalasia as the result of an autoimmune and inflammatory process leading to neuronal cell loss. According to this, idiopathic achalasia has been significantly associated with specific alleles of the human leukocyte antigen system class II, although few reports studying association with other loci can be found in the literature. Recent studies have shown association of a non-synonymous polymorphism within the IL23R gene with different chronic inflammatory disorders, including Barrett's esophagus. The purpose of this study was to assess whether the IL23R coding variant Arg381Gln polymorphism is involved in susceptibility to idiopathic achalasia. METHODS: We performed a case-control study including 262 patients with idiopathic achalasia and 802 healthy subjects, all of them white Spaniards. Achalasia patients were diagnosed on the basis of clinical, radiographic, endoscopic, and manometric criteria. All samples were genotyped for the IL23R Arg381Gln polymorphism using TaqMan technology. KEY RESULTS: The minor allele of the Arg381Gln polymorphism was significantly increased in patients compared with healthy controls (OR = 1.46, 95% CI = 1.01-2.11, P = 0.036). This association seems to be specific to male patients with disease onset after 40 years (OR = 2.33, 95% CI = 1.29-4.16, P = 0.002). CONCLUSIONS & INFERENCES: Our results suggest a role of IL23R in idiopathic achalasia predisposition and extend the evidence of the general influence of this gene in autoimmune and inflammatory diseases.

STAT3 locus in inflammatory bowel disease and multiple sclerosis susceptibility.

STAT3 (signal transducer and activator of transcription 3) signaling is a critical component of Th17-dependent autoimmune processes. Genome-wide association studies (GWAS) have revealed the role of the STAT3 gene in inflammatory bowel disease (IBD) susceptibility, although confirmation in clinical subphenotypes is warranted. Mice with targeted deletion of Stat3 in T cells are resistant to experimental autoimmune encephalomyelitis, which is a multiple sclerosis (MS) model. Moreover, increased phosphorylated STAT3 was reported in T cells of patients evolving from clinically isolated syndrome to defined MS and in relapsing patients. These evidences led us to analyze the role of STAT3 in Crohn's disease (CD), ulcerative colitis (UC) and MS risk. Polymorphisms in the STAT3 region (rs3809758/rs744166/rs1026916/rs12948909) were genotyped and the inferred haplotypes were subsequently analyzed in 860 IBD and 1540 MS Spanish patients and 1720 ethnically matched controls. The haplotype conformed by the risk alleles of each polymorphism was significantly associated with both clinical phenotypes of IBD (CD: P=0.005, odds ratio 1.25, 95% confidence interval 1.06-1.46; and UC: P=0.002, odds ratio 1.19, 95% confidence interval 1.02-1.38). No evidence of association was detected for MS. The originally described association of IBD with STAT3 polymorphisms is corroborated for the two clinical phenotypes, CD and UC, in an independent population. A major role of this gene in MS seems unlikely.

Chromosomal region 16p13: further evidence of increased predisposition to immune diseases.

OBJECTIVE: Genome-wide studies have identified the chromosomal region 16p13 in the susceptibility to type 1 diabetes (T1D) and multiple sclerosis (MS). This region includes the CLEC16A/KIAA0350 gene and an adjacent gene, MHC2TA (MHC class II transactivator), previously associated with susceptibility to MS and rheumatoid arthritis (RA). The role of CLEC16A polymorphisms in the pathogenesis of T1D, MS and RA and its relationship with the association reported with a MHC2TA haplotype were investigated. METHODS: CLEC16A (rs2903692/rs6498169/rs11074956) polymorphisms were analysed in 435 patients with MS, 316 with T1D and 600 with RA and in 550 ethnically matched controls. The MHC2TA rs3087456G/rs4774C risk haplotype was studied in an independent RA cohort. RESULTS: rs2903692 conferred a protective effect on patients with T1D, MS and RA. The described association of rs6498169 with MS was replicated in MS and RA cohorts. The effect of the MHC2TA rs3087456G/rs4774C haplotype on RA susceptibility was confirmed, and the haplotype was found to be in negative linkage disequilibrium with the CLEC16A rs2903692A/rs6498169A haplotype. CONCLUSIONS: Associations of CLEC16A polymorphisms with T1D and MS were successfully replicated in a Spanish population. A novel association of rs6498169 with a predisposition to RA was described which is consistent with previous MHC2TA results. These data provide evidence for the influence of variants within this chromosomal region on the development of complex diseases.

Effect of BSN-MST1 locus on inflammatory bowel disease and multiple sclerosis susceptibility.

Genome-wide studies highlighted the effect in Crohn's disease (CD) and ulcerative colitis (UC) susceptibility of single nucleotide polymorphisms (SNPs) in 3p21, where BSN (bassoon), MST1 (macrophage stimulating-1) and MST1R (MST1 Receptor) genes map. MST1R expression was significantly downregulated in multiple sclerosis (MS) compared with control brains, resembling findings in the MS mouse model. We pursued to replicate the effect of this locus on inflammatory bowel diseases and to evaluate its contribution to MS risk. Polymorphisms rs9858542, rs2131109 and rs1128535 were analysed by TaqMan assays in Spanish patients (370 CD, 405 UC and 415 MS) and 800 ethnically matched controls. Allele frequencies of these SNPs were significantly different in CD patients compared with controls [rs9858542: P=0.001, Odds ratio (OR)=1.35; rs2131109: P=0.0005, OR=1.37; rs1128535: P=0.007, OR=0.78] and, specifically, in the ileal phenotype [rs9858542: P=0.0004, OR=1.47; rs2131109: P=0.00009, OR=1.52; rs1128535: P=0.02, OR=0.69]. No differences were detected between UC or MS patients and control individuals. The effect of this locus on CD predisposition was replicated, but no influence on UC or MS predisposition could be detected. This susceptibility locus seems to affect mainly to the ileal CD subphenotype, although this point awaits further corroboration in independent cohorts.

Lack of replication of celiac disease risk variants reported in a Spanish population using an independent Spanish sample.

Celiac disease (CD) is an inflammatory condition affecting small bowel and triggered by gluten (or related proteins) ingestion in genetic susceptible individuals. Polymorphisms in three genes, SERPINE2, PPP6C and PBX3, have recently been associated with CD in the Spanish population. However, this association could not be replicated in the UK population using imputed data. As this second study analyzed a different population, we aimed at reevaluating the role of those polymorphisms using an independent Spanish sample. We genotyped three single nucleotide polymorphisms: rs6747096 in SERPINE2, rs458046 in PPP6C and rs7040561 in PBX3, in 417 CD patients, 527 ethnically matched healthy controls and parents of 304 CD patients. A case-control study using the chi(2)-test and a familial study using the transmission disequilibrium test were performed. No association was detected in those analyses. Therefore, our results seem to discard the role of the previously described polymorphisms in SERPINE2, PPP6C and PBX3 in CD susceptibility.

Glypican 5 is an interferon-beta response gene: a replication study.

BACKGROUND: Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system. Interferon-beta is the most usual therapy in relapsing-remiting MS. However, approximately 50% of the treated patients do not respond adequately. Very recently, a genome-wide association study on interferon-beta pharmacogenetics has described polymorphisms at several genes that are associated with response to this treatment. Our aim is to replicate the results obtained at the two loci most strongly implicated in the response to interferon-beta treatment, HAPLN1 and GPC5. PATIENTS AND METHODS: We performed a case-control study, analyzing 199 patients with MS treated with interferon-beta for at least 2 years and at least two documented relapses over the 2 years, previous to treatment onset. Responders had neither relapses nor increase in expanded disability status scale (EDSS) over the 2-year follow-up period, whereas nonresponders had at least two relapses or an increase in EDSS of at least 1 point. We studied three single-nucleotide polymorphisms (SNPs) in the GPC5 locus and three SNPs in the HAPLN1 locus by TaqMan technology. Allelic frequencies between responders and nonresponders were compared by a chi-square test. RESULTS: An association was found between GPC5 polymorphisms and the response to interferon-beta therapy in patients with MS, in agreement with earlier data (responder vs nonresponder patients: rs10492503, P = 0.0005). The other locus studied (HAPLN1) did not show association with treatment response to interferon-beta (all SNPs P > 0.05). CONCLUSIONS: We confirm the association of polymorphisms within GPC5 with response to interferon-beta therapy in patients with MS.

Association of IL18RAP and CCR3 with coeliac disease in the Spanish population.

BACKGROUND AND AIMS: Genome-wide association studies in coeliac disease (CD) have resulted in the finding of eight new genetic regions associated with disease susceptibility. However, a replication study performed in the Italian population could not confirm two of those new regions: 2q12 (IL18RAP) and 3p21 (CCR3). The aim of this study was to investigate the role of those regions in CD risk in a different Mediterranean population, the Spanish population. METHODS: A case-control study with 722 patients with CD and 794 ethnically matched healthy controls was performed. Two single-nucleotide polymorphisms, rs917997 (2q12) and rs6441961 (3p21), were genotyped and their genetic frequencies were compared between both groups using the chi(2) test. RESULTS: An association was found with rs6441961 (p = 0.0004, OR = 1.32, 95% CI 1.13 to 1.54). A non-significant result (but concordant with the initial study) was obtained for rs917997. CONCLUSION: The association of the 3p21 genetic region with CD susceptibility in the Spanish population was confirmed. In 2q12, the initially described OR is most probably overestimated and therefore the real situation may be the existence of a genuine but weak risk factor, which generates statistical power limitations.

HLA class I and II alleles and response to treatment with interferon-beta in relapsing-remitting multiple sclerosis.

In the present study, we investigated the influence of HLA class I and class II genes in the response to interferon-beta (IFNbeta) in multiple sclerosis (MS) patients. HLA-A, -B, -C, -DRB1, -DQA1, and -DQB1 DNA typing was performed by polymerase chain reaction-sequence-specific oligonucleotide (PCR-SSO) in a cohort of 149 relapsing-remitting MS patients classified into IFNbeta responders (n=74) and non-responders (n=75) based on stringent clinical criteria. Distribution of HLA class I and class II alleles individually and the HLA-DR2 haplotype was similar between responders and non-responders to treatment. These findings do not support a role of the HLA class I and class II genes as modifiers of the response to IFNbeta.

Role of polymorphisms in the TNFRSF13B (TACI) gene in Spanish patients with immunoglobulin A deficiency.

Mutations in the TNFRSF13B (TACI) gene have been associated with common variable immunodeficiency, and a role in immunoglobulin A deficiency (IgAD) has also been suggested. We aimed at studying the role of several polymorphisms along this gene in IgAD susceptibility. Three TNFRSF13B mutations (C104R, A181E and R202H) and eight additional single nucleotide polymorphisms in the gene were genotyped in 338 Spanish IgAD patients and 553 ethnically matched healthy controls and tested for association. Data from parents of 114 IgAD patients were also collected and used for additional analysis. No statistically significant differences were observed after comparing patients and controls for any single nucleotide polymorphism analysed. Therefore, our work seems to discard a role of TNFRSF13B mutations in IgAD, concordantly with the most recent published studies.

Autoimmune disease association signals in CIITA and KIAA0350 are not involved in celiac disease susceptibility.

Celiac disease (CD) is a multifactorial disease characterized by intestinal inflammation after gluten exposure in genetically susceptible individuals. A strong influence of certain human leukocyte antigen (HLA) alleles (those coding the HLA-DQ2 and DQ8 heterodimers) is well established, but they cannot explain the overall genetic risk. CIITA could be a good candidate gene for CD because it is mainly transcriptionally regulated, and it encodes the master regulator of major histocompatibilty complex class II gene transcription. CIITA is located in 16p13, a region also containing KIAA0350 (CLEC16A), associated with two autoimmune diseases in genome-wide association studies. We aimed at studying the involvement of polymorphisms in CIITA and KIAA0350 in CD susceptibility, with special attention to evaluate the possible presence of more than one risk factor in the region. We performed a case-control study with 607 CD patients and up to 794 healthy controls, all Spaniards. All samples were genotyped for five single nucleotide polymorphisms: rs3087456 (-168A/G) and rs4774 in CIITA and rs7203459, rs6498169 and rs2903692 in KIAA0350. No significant results were obtained when comparing genotypic, allelic or haplotypic frequencies between patients and controls. Our results seem to discard the influence in CD susceptibility of CIITA and KIAA0350 markers previously associated with other autoimmune diseases.

Association of the STAT4 gene with increased susceptibility for some immune-mediated diseases.

OBJECTIVE: The STAT4 gene encodes a transcription factor involved in the signaling pathways of several cytokines, including interleukin-12 (IL-12), the type I interferons, and IL-23. Recently, the association of a STAT4 haplotype marked by rs7574865 with rheumatoid arthritis (RA) and systemic lupus erythematosus was reported. The aim of this study was to investigate the role of this STAT4 tagging polymorphism in other immune-mediated diseases. METHODS: The study group comprised 2,776 consecutively recruited Spanish individuals: 575 with RA, 440 with multiple sclerosis, 700 with inflammatory bowel disease, 311 with type 1 diabetes, and 723 ethnically matched healthy control subjects. The STAT4 polymorphism rs7574865 was genotyped using a predesigned TaqMan assay. Allele and genotype frequencies in patients and control subjects were compared by chi-square test. RESULTS: The association of STAT4 polymorphism rs7574865 with RA was validated in patients of Spanish origin (for T versus G, P = 1.2 x 10(-6), odds ratio [OR] 1.59, 95% confidence interval [95% CI] 1.31-1.92), and the association was described for the first time in both clinical forms of inflammatory bowel disease, Crohn's disease and ulcerative colitis (for T versus G, P = 0.006, OR 1.29, 95% CI 1.07-1.55), and in type 1 diabetes mellitus (for T versus G, P = 0.008, OR 1.36, 95% CI 1.07-1.71). In contrast, the genotypic distribution of this polymorphism showed no difference between patients with multiple sclerosis and healthy control subjects (for T versus G, P = 0.83, OR 1.02, 95% CI 0.82-1.28). CONCLUSION: The STAT4 gene is emerging as a novel common risk factor for diverse complex diseases.

Study of the association between the CAPSL-IL7R locus and type 1 diabetes.

AIMS/HYPOTHESIS: In the past few years, several genes outside the MHC region have been described as new susceptibility genetic factors to type 1 diabetes. An association between CAPSL-rs1445898 and type 1 diabetes was reported in a large white population and corroborated in a genome-wide analysis, which also found an association with IL7R, which is located adjacent to CAPSL. The aim of this study was to replicate the aforementioned associations in independent cohorts. METHODS: We analysed two CAPSL (rs1010601 and rs1445898) and three IL7R (rs6897932, rs987106 and rs3194051) polymorphisms. All these single nucleotide polymorphisms (SNPs) were genotyped using TaqMan minor groove binder chemistry in 301 unrelated Spanish type 1 diabetes patients and 646 healthy controls. Additionally, the associated CAPSL SNP rs1445898 was genotyped in a Dutch cohort consisting of 429 type 1 diabetes patients and 720 healthy controls. RESULTS: The homozygous mutant genotype of the CAPSL SNP rs1445898 showed a trend towards a protective effect in the overall Spanish cohort (OR [95% CI] 0.70 [0.44-1.09]; p = 0.09) and in the Dutch cohort (OR [95% CI] 0.74 [0.51-1.05]; p = 0.09). Pooling of both cohorts was performed, yielding a statistically significant difference (Mantel-Haenszel OR 0.71; p = 0.005). This protective effect was significantly different in early-onset vs late-onset Spanish patients (OR [95% CI] 0.26 [0.10-0.65]; p = 0.001). Similarly, in the early-onset subgroup, the homozygous mutant genotype of the IL7R SNP rs6897932 showed a similar protective effect (OR [95% CI] 0.18 [0.02-0.94]; p = 0.02). CONCLUSIONS/INTERPRETATION: In summary, we describe an independent replication of the association between the CAPSL-IL7R locus and type 1 diabetes, especially for early-onset type 1 diabetes patients.

IL23R: a susceptibility locus for celiac disease and multiple sclerosis?

Recent studies have shown association of the IL23R gene with inflammatory bowel disease, psoriasis and ankylosing spondylitis. We aimed at studying the involvement of IL23R in celiac disease (CD) and multiple sclerosis (MS). We performed a case-control study including 598 patients with CD, 414 with MS and 546 healthy controls, all of them white Spaniards. All samples were genotyped for two single nucleotide polymorphisms: rs7517847 and rs11209026 (Arg381Gln). Statistical analyses were performed using chi(2-)tests or the Fisher's exact test. The minor allele (Gln) of the coding variant Arg381Gln was significantly increased in CD and MS patients when compared to controls (8% in CD vs 6% in controls, P=0.02; 9% in MS, P=0.006). In MS, a stronger effect was observed in patients showing primary-progressive disease (16%, P=0.004). Moreover, heterozygotes for rs7517847 were significantly increased in this group of MS patients (81% in MS vs 48% in controls, P=0.0002). In conclusion, contrary to what has been described previously, the less frequent allele of the functional polymorphism Arg381Gln (rs11209026) seems to be increasing susceptibility to CD and MS, although in this last group of patients a stronger effect is observed in patients affected of a primary-progressive form.