DRB1*03:01 haplotypes: differential contribution to multiple sclerosis risk and specific association with the presence of intrathecal IgM bands

Background

Multiple sclerosis (MS) is a multifactorial disease with a genetic basis. The strongest associations with the disease lie in the Human Leukocyte Antigen (HLA) region. However, except for the DRB1*15:01 allele, the main risk factor associated to MS so far, no consistent effect has been described for any other variant. One example is HLA-DRB1*03:01, with a heterogeneous effect across populations and studies. We postulate that those discrepancies could be due to differences in the diverse haplotypes bearing that allele. Thus, we aimed at studying the association of DRB1*03:01 with MS susceptibility considering this allele globally and stratified by haplotypes. We also evaluated the association with the presence of oligoclonal IgM bands against myelin lipids (OCMB) in cerebrospinal fluid.

Methods

Genotyping of HLA-B, -DRB1 and -DQA1 was performed in 1068 MS patients and 624 ethnically matched healthy controls. One hundred and thirty-nine MS patients were classified according to the presence (M+, 58 patients)/absence (M−, 81 patients) of OCMB. Comparisons between groups (MS patients vs. controls and M+ vs. M−) were performed with the chi-square test or the Fisher exact test.

Results

Association of DRB1*03:01 with MS susceptibility was observed but with different haplotypic contribution, being the ancestral haplotype (AH) 18.2 the one causing the highest risk. Comparisons between M+, M− and controls showed that the AH 18.2 was affecting only M+ individuals, conferring a risk similar to that caused by DRB1*15:01.

Conclusions

The diverse DRB1*03:01-containing haplotypes contribute with different risk to MS susceptibility. The AH 18.2 causes the highest risk and affects only to individuals showing OCMB.

Dense genotyping identifies and localizes multiple common and rare variant association signals in celiac disease

Using variants from the 1000 Genomes Project pilot European CEU dataset and data from additional resequencing studies, we densely genotyped 183 non-HLA risk loci previously associated with immune-mediated diseases in 12,041 individuals with celiac disease (cases) and 12,228 controls. We identified 13 new celiac disease risk loci reaching genome-wide significance, bringing the number of known loci (including the HLA locus) to 40. We found multiple independent association signals at over one-third of these loci, a finding that is attributable to a combination of common, low-frequency and rare genetic variants. Compared to previously available data such as those from HapMap3, our dense genotyping in a large sample collection provided a higher resolution of the pattern of linkage disequilibrium and suggested localization of many signals to finer scale regions. In particular, 29 of the 54 fine-mapped signals seemed to be localized to single genes and, in some instances, to gene regulatory elements. Altogether, we define the complex genetic architecture of the risk regions of and refine the risk signals for celiac disease, providing the next step toward uncovering the causal mechanisms of the disease.

Association of IL10 promoter polymorphisms with idiopathic achalasia

Idiopathic achalasia is an esophageal motor disorder of unknown etiology. A wealth of evidence supports the concept that achalasia is an immune-mediated disease. According to this evidence, achalasia has been significantly associated with specific alleles of the human leukocyte antigen class II, PTPN22 and IL23R. Several studies have demonstrated association of the IL10 gene with different inflammatory disorders. Our aim was to evaluate the role of functional IL10 promoter polymorphisms in susceptibility to idiopathic achalasia. A case-control study was performed with the -1082, -819, and -592 IL10 promoter polymorphisms in 282 patients and 529 controls and in an independent replication set of 75 patients and 575 controls. The GCC haplotype of the IL10 promoter was reported to be associated with a lower risk of achalasia in the discovery sample (odds ratio [OR] = 0.79, 95% confidence interval [CI] = 0.64-0.98, p = 0.029). This association was validated in a replication set (OR = 0.69, 95% CI = 0.48-1.00, p = 0.04). In the combined analysis no heterogeneity was observed between the 2 sample sets and the GCC haplotype was significantly associated with the disease (OR(MH) = 0.76, 95% CI = 0.63-0.91, p = 0.003). Our results provide the first evidence for an association between IL10 promoter polymorphisms and idiopathic achalasia, suggesting that the interleukin-10 cytokine may contribute to the pathogenesis of this disease.

A polymorphism in PTPN2 gene is associated with an earlier onset of type 1 diabetes

The Wellcome Trust Case Control Consortium (WTCCC) genome-wide study found association of PTPN2 with three autoimmune diseases, among them is type 1 diabetes (T1D). This result was confirmed by a follow-up study that pointed to new independent signals within the region. However, both studies were performed in patients with an early-onset T1D. We aimed at replicating the previous results and studying the influence of these polymorphisms in the age at T1D debut. We genotyped 439 T1D Spanish subjects (age at onset, 1 to 65 years) and 861 controls for two PTPN2 single nucleotide polymorphisms (SNPs), rs2542151 and rs478582, and studied the effect of both polymorphisms in age at onset through stratified and continuous analyses. The frequency of rs2542151*G carriers was significantly higher in the early-onset group compared with late-onset patients (p = 0.023) and with controls (OR = 1.61 [1.14-2.26]; p = 0.005). No significant differences were found between controls and late-onset patients. The log-rank chi-square test for the Kaplan-Meier plots (carriers of susceptibility allele vs non carriers) was statistically significant (χ (1df) (2)  = 4.485; p = 0.034), yielding an earlier disease debut for G carriers. The analysis of the SNP rs478582 did not reach statistical significance. In summary, we replicate the association detected by the WTCCC and propose that the rs2542151*G allele confers risk to an earlier onset of T1D.

CD40: novel association with Crohn's disease and replication in multiple sclerosis susceptibility

BACKGROUND

A functional polymorphism located at -1 from the start codon of the CD40 gene, rs1883832, was previously reported to disrupt a Kozak sequence essential for translation. It has been consistently associated with Graves' disease risk in populations of different ethnicity and genetic proxies of this variant evaluated in genome-wide association studies have shown evidence of an effect in rheumatoid arthritis and multiple sclerosis (MS) susceptibility. However, the protective allele associated with Graves' disease or rheumatoid arthritis has shown a risk role in MS, an effect that we aimed to replicate in the present work. We hypothesized that this functional polymorphism might also show an association with other complex autoimmune condition such as inflammatory bowel disease, given the CD40 overexpression previously observed in Crohn's disease (CD) lesions.

METHODOLOGY

Genotyping of rs1883832C>T was performed in 1564 MS, 1102 CD and 969 ulcerative colitis (UC) Spanish patients and in 2948 ethnically matched controls by TaqMan chemistry.

PRINCIPAL FINDINGS

The observed effect of the minor allele rs1883832T was replicated in our independent Spanish MS cohort [p = 0.025; OR (95% CI) = 1.12 (1.01-1.23)]. The frequency of the minor allele was also significantly higher in CD patients than in controls [p = 0.002; OR (95% CI) = 1.19 (1.06-1.33)]. This increased predisposition was not detected in UC patients [p = 0.5; OR (95% CI) = 1.04 (0.93-1.17)].

CONCLUSION

The impact of CD40 rs1883832 on MS and CD risk points to a common signaling shared by these autoimmune conditions.

MSH5 is not a genetic predisposing factor for immunoglobulin A deficiency but marks the HLA-DRB1*0102 subgroup carrying susceptibility

The etiology of selective IgA deficiency (IgAD) is clearly influenced by human leukocyte antigen (HLA) genetic composition, although the susceptibility observed has not been ascribed to any specific gene/s. A possible role of the MSH5 gene, mapping on this chromosomal region, has been proposed based on its function and on the association of some MSH5 polymorphisms (L85F/P786S and rs3131378) with the disease. However, the extensive linkage disequilibrium in the HLA region makes mandatory additional analyses. We aimed at evaluating the role of those MSH5 polymorphisms on IgAD susceptibility considering their linkage with other classically associated HLA markers, specifically DRB1*0102 and B*08-DRB1*03. We studied 146 trios composed by IgAD patient and parents to unambiguously establish the gametic phase. Association of those MSH5 variants with IgAD is observed but stratified analyses considering other HLA alleles rule out the role of MSH5 per se as a predisposing factor. However, the minor allele of one of the studied polymorphisms, 85F, defines the subgroup of DRB1*0102 haplotypes carrying susceptibility. The causal factor present on this haplotype (MSH5 85F-DRB1*0102) seems to be at the telomeric end of HLA class II or in Class I or III, as the allele composition in more centromeric markers is shared by all the haplotypes containing DRB1*0102.

Polymorphisms in the IL2, IL2RA and IL2RB genes in multiple sclerosis risk

Interleukin (IL)-2/IL-2R signalling promotes proliferation and survival of activated T cells and has an essential non-redundant role in the production of regulatory T cells. Associations with different autoimmune diseases of polymorphisms in a linkage disequilibrium block in which the IL2/IL21 genes map (4q27), and also in genes encoding the IL2RA and IL2RB subunits (located in 10p15 and 22q13, respectively), were identified through genome-wide studies. Polymorphisms in these three genes were studied in 430 multiple sclerosis (MS) patients and in 550 ethnically matched controls from Madrid (Spain). Replication and meta-analysis with results from an independent cohort of 771 MS patients and 759 controls from Andalucía (Spain) confirmed the association of polymorphisms in the IL2RA gene (P(Mantel-Haenszel,) odds ratio (OR)(M-H) (95% confidence interval, CI) for rs2104286: 0.0001, 0.75 (0.65-0.87); for rs11594656/rs35285258: 0.004, 1.19 (1.06-1.34); for rs41295061: 0.03, 0.77 (0.60-0.98)); showed a trend for association of the IL2/IL21 rs6822844 (P(M-H)=0.07, OR(M-H) (95% CI)=0.86 (0.73-1.01)), but did not corroborate the association for IL2RB. Regression analyses of the combined Spanish cohort revealed the independence of two IL2RA association signals: rs2104286 and rs11594656/rs35285258. The relevant role of the IL2RA gene on MS susceptibility adds support to its common effect on autoimmune risk and the suggestive association of IL2/IL21 warrants further investigation.

The IL6-174G/C polymorphism is associated with celiac disease susceptibility in girls

The aim of this paper was to study the role of IL6 and IL6R polymorphisms in celiac disease (CD) susceptibility. Because previous literature describes IL-6-related gender differences, sex-stratified analyses were performed. We undertook a case-control study with 374 pediatric CD patients and 853 healthy controls, all white Spaniards, and a family study using an independent sample including 303 trios for replication purposes. Three single-nucleotide polymorphisms tagging most of the variability of the IL6 gene (rs2069827, rs1800795 [-174G/C], and rs2069840) and one functional polymorphism in IL6R (rs8192284, Asp358Ala) were genotyped using TaqMan technology. Case-control comparisons were performed with the chi2 test and family data were analyzed with the transmission disequilibrium test. No association was observed between any tested polymorphism and overall CD. However, after sex stratification, we found that the IL6 promoter variant -174C increases the risk of developing CD specifically in female patients. This effect was observed both in the case-control and in the family studies (considering girls included in both studies vs boys: p = 0.021, odds ratio [OR] = 1.31, 95% confidence interval [CI] 1.03-1.66; and vs controls: p = 0.003, OR = 1.30, 95% CI 1.09-1.55). The functional -174G/C IL6 polymorphism seems to influence CD susceptibility in girls. The gender-specific role of IL-6 in this pathology must be further investigated.

Role of ATG16L1 Thr300Ala polymorphism in inflammatory bowel disease: a Study in the Spanish population and a meta-analysis

BACKGROUND

Thr300Ala polymorphism in ATG16L1 was reported as a susceptibility factor to Crohn's disease (CD). Inconsistently replicated associations with ulcerative colitis (UC) and specifically with ileal CD were also reported. Our aims were: to replicate the ATG16L1 Thr300Ala association with inflammatory bowel disease (IBD) in the Spanish population, to perform a meta-analysis to determine the risk conferred to the different IBD subgroups, and to test for the interaction with CARD15 or IL23R risk loci.

METHODS

Thr300Ala (rs2241880) single nucleotide polymorphism (SNP) was genotyped in 712 IBD patients and 745 controls by TaqMan technology. Genetic frequencies were compared with chi-square tests. Our findings were pooled in a meta-analysis.

RESULTS

In Spain, we observed an association of rs2241880 with CD (P = 0.008; odds ratio [OR, 95% confidence interval, CI] = 1.28 [1.06-1.54]), but not with UC. No significant differences emerged when patients were stratified by clinical features. Similarly, the meta-analysis demonstrated a significant association only with CD (P < 10(-4); OR [95% CI] = 1.33 [1.28-1.38]). A significant difference between ileal CD patients and controls was observed, but heterogeneity was found in comparisons involving colonic CD patients and definite conclusions cannot be drawn. No interaction between rs2241880 and the established CARD15 or IL23R susceptibility variants was observed.

CONCLUSIONS

The Thr300Ala polymorphism is associated with CD, regardless of the CARD15 or IL23R status, but not with UC. Stratification by clinical phenotypes did not show definitive results because of the existing heterogeneity among studies.

FcRL3 gene promoter variant is associated with peripheral arthritis in Crohn's disease

BACKGROUND

The mechanisms responsible for the pathogenesis of peripheral arthropathies (PA) in Crohn's disease (CD) are largely unknown, although many studies indicate that genetic and environmental factors are likely to contribute to risk.

METHODS

Because variants in the Fc receptor-like 3 (FcRL3) gene have recently been associated with rheumatoid arthritis and several other autoimmune diseases, we tested 2 FcRL3 promoter variants (-169 C>T and -110 G>A) for association with PA in Spanish CD patients that were recruited from a single center and followed for at least 4 years (mean follow-up time, 11 years).

RESULTS

Among the 342 CD patients evaluated, there were 88 cases of peripheral arthropathy; 31 were classified as arthritis and 57 were classified as arthralgia. We used contingency tables and logistic regression to test for association between PA or either subtype and FcRL3 and other factors that have previously been associated with extraintestinal manifestations in CD.

CONCLUSIONS

We found that female sex, colonic involvement, and the AA genotype at -110 G>A were associated with increased risk of both subtypes of PA, although the association appears to be stronger for arthritis than for arthralgia.

Lack of association of NKX2-3, IRGM, and ATG16L1 inflammatory bowel disease susceptibility variants with celiac disease

Evidence about the presence of susceptibility factors shared among different autoimmune diseases is increasing. Based on this idea, NKX2-3, ATG16L1, and IRGM which are well-established inflammatory bowel disease risk factors, could be new celiac disease (CD) candidate genes. NKX2-3 encodes a transcription factor that in mice seems to be involved in gut development. The ATG16L1 and IRGM genes act in autophagy, a process related to innate and adaptive immunity. We aimed to study the implication of five polymorphisms in these genes in CD susceptibility: rs10883365 and rs888208 in the NKX2-3 gene, rs2241880 in ATG16L1, and rs10065172 and rs4958847 in IRGM. Association studies were performed using 725 Spanish CD patients and 956 ethnically matched healthy controls, as well as 309 parent-child trios. Genetic frequencies were compared with the chi(2) test and the familial study used the transmission disequilibrium test. Differences between CD patients and controls did not reach significance when genotypic and allelic frequencies were compared. No differential transmission of alleles or haplotypes from heterozygous parents to affected children was observed in the familial study. In conclusion, no evidence of association with CD has been reported for the Crohn's disease susceptibility polymorphisms studied in the NKX2-3, ATG16L1, and IRGM genes.

Novel association of the interleukin 2-interleukin 21 region with inflammatory bowel disease

OBJECTIVES

Genome-wide association studies have reported the role of the interleukin (IL) 2-IL21 chromosomal region at 4q27 in several autoimmune conditions. Mice deficient in IL-2 develop a disease with clinical and histological similarity to ulcerative colitis (UC) in humans. Modest evidence of linkage with UC was tentatively proposed for the IL2 gene more than a decade ago. Therefore, we decide to investigate the association of polymorphisms in the IL-2 axis (IL2, IL2RA, and IL2RB genes) with inflammatory bowel diseases (IBDs).

METHODS

Seven hundred and twenty-eight white Spanish unrelated IBD patients (356 Crohn's disease (CD) and 372 UC) and 549 ethnically matched controls were included in a case-control study. In addition, a Spanish replication cohort with 562 CD and 430 UC patients and 1,310 controls were analyzed. Eight single-nucleotide polymorphisms previously associated with different autoimmune diseases were analyzed using TaqMan chemistry.

RESULTS

The IL2-rs6822844 polymorphism modified CD predisposition (P=0.002; odds ratio, OR (95% confidence interval, CI)=0.61 (0.44-0.84)); this was replicated in the other Spanish cohort, resulting in a strong protective effect of the minor allele in the merged samples (P=0.0002; OR (95% CI)=0.70 (0.58-0.85)). A similar effect of rs6822844 was detected for UC. Another marker, rs11938795, also showed evidence of an association with CD (P=0.006; OR (95% CI)=0.73 (0.58-0.92)).

CONCLUSIONS

Polymorphisms within the IL2-IL21 linkage disequilibrium (LD) block show a novel association with IBD, this is concordant with suggestive previous results of whole genome analyses in CD and type 1 diabetes. Our data agree with the effect previously observed for other conditions and delineate a shared underlying mechanism.

Localization of Type 1 Diabetes susceptibility in the ancestral haplotype 18.2 by high density SNP mapping

Previous studies have suggested that the ancestral haplotype 18.2 (AH18.2) carries additional susceptibility gene to Type 1 Diabetes (T1D) on the Major Histocompatibility Complex (MHC). We analyzed 10 DR3/TNFa1b5 homozygous subjects in order to establish the conservation of the AH18.2 and then compared this conserved region with other DR3 haplotype, the AH8.1. The Illumina's HumanHap550 Bead chip was used to perform an extensive genotyping of the MHC region. The AH18.2 was highly conserved between DDR1 and HLA-DQA1 genes; therefore most probably the second susceptibility gene is located within this region. We can exclude the region centromeric to HLA-DRA gene and telomeric to DDR1 gene. A comparison between the AH18.2 and AH8.1 haplotypes showed that 233 SNPs were different in the aforementioned conserved region. These data suggest that the 1.65 Mb MHC region between DDR1 and HLA-DRA genes is likely to carry additional susceptibility alleles for T1D on the AH18.2 haplotype.

Specific association of a CLEC16A/KIAA0350 polymorphism with NOD2/CARD15(-) Crohn's disease patients

Independent genome-wide association studies highlighted the function of CLEC16A/KIAA0350 polymorphisms modifying the risk to either multiple sclerosis (rs6498169) or type 1 diabetes (rs2903692). This C-type lectin gene maps to a linkage disequilibrium block at 16p13 and a functional role of this gene could be envisaged for other immune-related conditions, such as inflammatory bowel disease (IBD). The present study, aimed at investigating the association of those two polymorphisms with IBD, included 720 IBD patients and 550 ethnically matched healthy controls. The effect of rs2903692 previously described in diabetes was observed specifically for Crohn's disease (CD) patients lacking the main susceptibility factor described to date, that is, three polymorphisms within another pattern recognition gene, NOD2/CARD15 (NOD2(-) vs NOD2(+) CD patients, G vs A: P=0.008; OR (95% CI)=1.54 (1.10-2.15); NOD2(-) CD patients vs controls: P=0.008; OR (95% CI)=1.37 (1.08-1.73)). Replication of these findings was performed in independent Spanish cohorts of 544 IBD patients and 340 controls and the combined data yielded significant differences (405 NOD2(-) vs 204 NOD2(+) CD patients, G vs A: P=0.0012; OR(M-H) (95% CI)=1.49 (1.17-1.90); NOD2(-) CD patients vs controls: P=0.0007; OR(M-H) (95% CI)=1.35 (1.13-1.60)). The pooled analysis of the ulcerative colitis patients vs controls also yielded a significant risk (P=0.0005; OR (95% CI)=1.52 (1.19-1.93)). These data would suggest that microbial recognition through different pathways seems to converge in the development of these polygenic bowel diseases.

Polymorphisms in the selenoprotein S gene: lack of association with autoimmune inflammatory diseases

Background

Selenoprotein S (SelS) protects the functional integrity of the endoplasmic reticulum against the deleterious effects of metabolic stress. SEPS1/SelS polymorphisms have been involved in the increased release of pro-inflammatory cytokines interleukin (IL)-1β, tumor necrosis factor (TNF)-α and IL-6 in macrophages. We aimed at investigating the role of the SEPS1 variants previously associated with higher plasma levels of these cytokines and of the SEPS1 haplotypes in the susceptibility to develop immune-mediated diseases characterized by an inflammatory component.

Results

Six polymorphisms distributed through the SEPS1 gene (rs11327127, rs28665122, rs4965814, rs12917258, rs4965373 and rs2101171) were genotyped in more than two thousand patients suffering from type 1 diabetes, rheumatoid arthritis or inflammatory bowel diseases and 550 healthy controls included in the case-control study.

Conclusion

Lack of association of SEPS1 polymorphisms or haplotypes precludes a major role of this gene increasing predisposition to these inflammatory diseases.

IFIH1-GCA-KCNH7 locus: influence on multiple sclerosis risk

A recent genome-wide scan of nonsynonymous SNPs and ulterior validation in case-control and family analyses evidenced a susceptibility locus for type 1 diabetes (T1D) on chromosome 2q24.3. We aimed at testing the effect of this locus in other autoimmune diseases with complex genetic background, such as multiple sclerosis (MS). Four SNPs along the locus, rs13422767, rs2111485, rs1990760 and rs2068330, were genotyped using TaqMan MGB chemistry in 311 T1D and 412 MS patients and 535 ethnically matched healthy controls. The previously reported association of this locus was found for the first time in MS (rs2068330, G vs C: P=0.001; OR (95% CI)=0.73 (0.6-0.88)) and a trend for replication was observed in our Spanish diabetic cohort. Therefore, genes included in this locus - IFIH1 interferon induced helicase, GCA grancalcin or the potassium channel KCNH7 - are potential candidates implicated in the pathogenesis of these autoimmune diseases, although strong linkage disequilibrium in the region hampered further localization of the etiologic gene.

CD209 in inflammatory bowel disease: a case-control study in the Spanish population

BACKGROUND

The etiology of Ulcerative Colitis (UC) and Crohn's Disease (CD), considered together as Inflammatory Bowel Diseases (IBD), involves environmental and genetic factors. Although some genes are already known, the genetics underlying these diseases is complex and new candidates are continuously emerging. The CD209 gene is located in a region linked previously to IBD and a CD209 functional polymorphism (rs4804803) has been associated to other inflammatory conditions. Our aim was to study the potential involvement of this CD209 variant in IBD susceptibility.

METHODS

We performed a case-control study with 515 CD patients, 497 UC patients and 731 healthy controls, all of them white Spaniards. Samples were typed for the CD209 single nucleotide polymorphism (SNP) rs4804803 by TaqMan technology. Frequency comparisons were performed using chi2 tests.

RESULTS

No association between CD209 and UC or CD was observed initially. However, stratification of UC patients by HLA-DR3 status, a strong protective allele, showed that carriage of the CD209_G allele could increase susceptibility in the subgroup of HLA-DR3-positive individuals (p = 0.03 OR = 1.77 95% CI 1.04-3.02, vs. controls).

CONCLUSION

A functional variant in the CD209 gene, rs4804803, does not seem to be influencing Crohn's disease susceptibility. However, it could be involved in the etiology or pathology of Ulcerative Colitis in HLA-DR3-positive individuals but further studies are necessary.

Role of the PXR gene locus in inflammatory bowel diseases

BACKGROUND

The pregnane X receptor gene (PXR/NR1I2) has been recently associated with an increased risk for inflammatory bowel disease (IBD), although a subsequent case-control study failed to replicate the original association in an independent population. This nuclear receptor regulates genes involved in the detoxification process in the liver and intestine, like ABCB1/MDR1. PXR expression was significantly reduced in the colon of patients with ulcerative colitis (UC), but remained unaffected in Crohn's disease (CD) patients. Considering previous results, we aimed at investigating the impact of this locus on IBD predisposition in the Spanish population.

METHODS

Three PXR polymorphisms, including the 1 more strongly correlated with IBD risk in the initial study at -25385C/T (rs3814055) and the 6 haplotypes conformed by them, were analyzed in 365 UC and 331 CD patients and compared with 550 ethnically matched controls.

RESULTS

The overall haplotypic distribution showed a significant difference between UC and CD patients (P = 0.05; chi(2) = 10.84). Among UC patients a significant difference was seen between those with extensive colitis and controls (P = 0.004; chi(2) = 17.04), mainly due to the presence of a risk haplotype (rs3814055*T//rs6784598*C//rs2276707*C: P = 0.001; odds ratio [OR] = 1.66, 95% confidence interval [CI] 1.20-2.30). Patients with extensive UC carrying the -25385T allele showed increased susceptibility compared with left-sided colitis patients and with healthy subjects. In patients with extensive UC a significantly different distribution of genotypes of the MDR1 G/A change located in intron 3 (rs3789243) was observed between carriers/noncarriers of the -25385T risk allele (P = 0.005).

CONCLUSIONS

Our data seem to support the association of the PXR locus with extensive UC and the interaction between PXR and MDR1 genes.

Strong protective effect of DR3 against ulcerative colitis in the Spanish population

OBJECTIVES

Ulcerative colitis (UC) is a chronic inflammatory disease affecting the colon. Major histocompatibility complex (MHC) on the short arm of human chromosome 6 has been thoroughly studied as a susceptibility locus. However, one of the strongest MHC associations found, that of HLA-DR3 with UC protection, has not been observed in all populations. Our aim in the present study was to evaluate this negative association in a large cohort of Spanish UC patients and controls, and to try to elucidate which, if any, of the diverse DR3 haplotypes (identified by TNFa and b microsatellites, located in the MHC class III region) is most tightly associated (negatively) with the disease.

METHODS

A total of 537 UC patients and 748 healthy controls from Spain were included in the present study. Low-resolution DR genotyping was performed by PCR and hybridization with allele-specific oligonucleotide probes. TNFa and b microsatellites were studied in a subset of samples (279 UC patients and 503 healthy controls) by PCR followed by capillary electrophoresis. DR-TNFa-TNFb haplotypes were estimated by the expectation-maximization algorithm and comparisons were performed by a chi2 test.

RESULTS

After a stepwise procedure, the only DR alleles significantly associated with the disease were DR3 (very strongly, protection) and DR4 (weakly, protection). The strong protective effect of DR3 was evenly distributed among the haplotypes DR3-TNFa1b5, DR3-TNFa2b3, and DR3-TNFother.

CONCLUSIONS

Our results confirm the strong protective effect of DR3 in our population, and suggest that the relevant protective gene is located centromeric to TNFa and TNFb markers in the MHC region.

TLR4 haplotypes in multiple sclerosis: a case-control study in the Spanish population

Our aim in the present study is to evaluate the variation present in the TLR4 gene and its relationship with multiple sclerosis susceptibility in the Spanish population. Three hundred and sixty-two multiple sclerosis patients and 467 healthy controls from the Spanish population were included in the present study. Twelve single nucleotide polymorphisms (SNPs) were selected, and analyzed by the TaqMan technique. No statistically significant differences for any polymorphism or haplotypes were observed when patients were compared with controls. In conclusion, TLR4 does not play a major role in the predisposition to suffer from multiple sclerosis in our population.

FcRL3 and multiple sclerosis pathogenesis: Role in autoimmunity?

BACKGROUND AND AIMS

A functional promoter polymorphism in the FcRL3 gene, -169 T/C, has been shown to regulate gene expression and to play a role in several autoimmune diseases. We aimed at testing for the first time whether this gene was involved in multiple sclerosis (MS) pathogenesis.

METHODS

Case-control study performed with 400 Spanish MS patients and 508 healthy subjects. Genotyping of -169 T/C and -110 G/A was ascertained by using TaqMan MGB chemistry following manufacturer suggestions (Applied Biosystems, CA, USA).

RESULTS

As previously seen for other autoimmune diseases, a significant difference was observed in the distribution of -169 T/C FcRL3 genotypes between MS patients and healthy controls (p = 0.03; chi(2) = 6.99). The -169 T allele, recently associated with increased susceptibility to Addison's disease, showed a parallel effect in MS [(TT+TC) vs. CC: p = 0.013; OR = 1.55 (1.08-2.54)].

CONCLUSIONS

An increased susceptibility associated to the -169 T allele was found when MS patients and controls were compared, supporting the role of the FcRL3 locus in MS predisposition and therefore extending the evidence of its general influence on autoimmunity.

Susceptibility to type 1 diabetes conferred by the PTPN22 C1858T polymorphism in the Spanish population

Background

The protein tyrosine phosphatase N22 gene (PTPN22) encodes a lymphoid-specific phosphatase (LYP) which is an important downregulator of T cell activation. A PTPN22 polymorphism, C1858T, was found associated with type 1 diabetes (T1D) in different Caucasian populations. In this study, we aimed at confirming the role of this variant in T1D predisposition in the Spanish population.

Methods

A case-control was performed with 316 Spanish white T1D patients consecutively recruited and 554 healthy controls, all of them from the Madrid area. The PTPN22 C1858T SNP was genotyped in both patients and controls using a TaqMan Assay in a 7900 HT Fast Real-Time PCR System.

Results

We replicated for the first time in a Spanish population the association of the 1858T allele with an increased risk for developing T1D [carriers of allele T vs. CC: OR (95%) = 1.73 (1.17–2.54); p = 0.004]. Furthermore, this allele showed a significant association in female patients with diabetes onset before age 16 years [carriers of allele T vs. CC: OR (95%) = 2.95 (1.45–6.01), female patients vs female controls p = 0.0009]. No other association in specific subgroups stratified for gender, HLA susceptibility or age at onset were observed.

Conclusion

Our results provide evidence that the PTPN22 1858T allele is a T1D susceptibility factor also in the Spanish population and it might play a different role in susceptibility to T1D according to gender in early-onset T1D patients.

Macrophage migration inhibitory factor gene: influence on rheumatoid arthritis susceptibility

The macrophage inhibitory factor (MIF) is a cytokine that has been implicated in several inflammatory and autoimmune diseases, including rheumatoid arthritis, systemic lupus, glomerulonephritis, and multiple sclerosis. In rheumatoid arthritis (RA), results ranging from lack of association of MIF polymorphisms with RA, to involvement in either severity or susceptibility to the disease have been reported in the past. We aimed at investigating the role of this gene in RA in the Spanish population. Two well-known MIF promoter polymorphisms were tested in 606 adult RA patients and 886 healthy controls: a single nucleotide polymorphism at -173G/C and a tetranucleotide repeat (CATT)(5-8) located at -794. We found a significant association of the allele -173C with RA (p = 0.01; odds ratio [OR] = 1.31; 95% confidence interval [CI] = 1.06-1.62). The -173C risk allele, previously reported to be transmitted in excess in patients with juvenile idiopathic arthritis, was significantly more frequent in early-onset adult RA patients than in healthy controls (p = 0.003; OR = 1.57; 95% CI = 1.14-2.15), whereas late-onset patients were not significantly different to controls (p = 0.6; OR = 1.09; 95% CI = 0.77-1.55). In conclusion, the -173C allele in the MIF promoter region is associated with increased RA predisposition, mainly in early-onset patients.

Environment-gene interaction in multiple sclerosis: human herpesvirus 6 and MHC2TA

Multiple sclerosis (MS) is an inflammatory disorder affecting the central nervous system, in which both genetic and environmental factors interact. Among these environmental contributors, herpesvirus has been proposed as an important etiologic factor. CIITA is a transcription factor controlling the expression of MHC class II genes, the main genetic determinants of MS susceptibility. This gene has been described as a target of the immunoevasive strategies, and it is therefore an attractive candidate gene to be at the genetic-viral crossroads. Two polymorphisms in MHC2TA gene (rs4,774G/C and rs3,087,456A/G) were studied in two groups: one in 22 multiple sclerosis patients with active human herpes virus 6 (HHV-6A) replication (HHV-6A-positive), and the other of 77 patients with no detectable HHV-6A active infection (HHV-6A-negative); a Spanish healthy control group (n = 520) was also included as external control. An association of the rs4,774C allele with the HHV-6A-positive group was found when compared with the HHV-6A-negative (47.7% vs 18.8%, p = 0.0001; odds ratio = 3.94) and also with the control group (47.7% vs 25.5%, p = 0.001, odds ratio = 2.67). No significant differences were observed between HHV-6A-negative subjects and healthy controls. Our data suggest that a strong gene-environment interaction occurs between HHV-6A active replication and MHC2TA rs4,774C or another polymorphism in tight linkage disequilibrium with it. Besides, this report indicates that when patients are grouped based upon a well-defined molecular event, complex diseases may reveal themselves as being constituted by distinct entities in which some genes may have a strong influence.

MDR1 polymorphisms and response to azathioprine therapy in patients with Crohn's disease

BACKGROUND

To investigate the contribution of multidrug resistance 1 (MDR1) gene pharmacogenetics (G2677T/A and C3435T) to the efficacy of azathioprine in inducing remission in patients with Crohn's disease (CD).

METHODS

A cohort of 327 unrelated Spanish patients with CD recruited from a single center was studied. All patients were rigorously followed up for at least 2 years (mean time, 11.5 years). A case-control analysis of MDR1 G2677T/A and C3435T SNPs and 2 loci haplotypes in 112 steroid-dependent CD patients treated with azathioprine was performed. Patients were classified on the basis of response to azathioprine.

RESULTS

A total 76 patients treated with azathioprine for longer than 3 months were included. Remission was achieved in 42 CD patients (55.3%). A higher frequency of the 2677TT genotype was found in nonresponders than in responders (17.65% versus 7.14%; OR = 2.8; 95% CI; 0.6-12.1; P = 0.11). Nonresponders to azathioprine were found to have a higher frequency of the 3435TT genotype than did CD patients who had achieved clinical remission (17.64% versus 4.76%; OR = 4.3; 95% CI, 0.8-22.8; P = 0.06). The 2677T/3435T haplotype was also more abundant in nonresponders (29.4% versus 20.2%), whereas the 2677G/3435C haplotype was more frequent in responders (58.3% versus 47.1%). Lack of response to azathioprine therapy in CD patients was 1.8-fold greater in carriers of the 2677T/3435T haplotype than in carriers of the 2677G/3435C haplotype (OR = 1.8; 95% CI, 0.82-3.9; P = 0.14).

CONCLUSIONS

The results of our study indicate higher frequencies of the 2677TT and 3435TT genotypes and the 2677T/3435T haplotype in CD patients who did not respond to azathioprine. Additional replications in independent populations would confirm the real impact of these polymorphisms in response to azathioprine therapy.

Role of the MHC2TA gene in autoimmune diseases

OBJECTIVES

Expression of major histocompatibility complex (MHC) class II genes is almost exclusively regulated by the class II transactivator. A promoter polymorphism (-168A/G, rs3087456) in the MHC2TA gene was associated with increased susceptibility to rheumatoid arthritis, multiple sclerosis and myocardial infarction in a northern European population. However, no evidence of association of this MHC2TA variant with the two autoimmune diseases could be subsequently detected in independent cohorts.

AIM

To test the aforementioned single nucleotide polymorphism and another G-->C change (nt1614 from coding sequence, rs4774) to analyse the haplotype pattern in this MHC2TA gene.

METHODS

A case-control study was performed with 350 patients with rheumatoid arthritis, 396 patients with multiple sclerosis, 663 patients with inflammatory bowel disease (IBD) and 519 healthy controls from Madrid. Genotyping was ascertained by using TaqMan assays-on-demand on a 7900HT analyser, following the manufacturer's suggestions (Applied Biosystems, Foster City, California, USA). Haplotypes were inferred with the expectation-maximisation algorithm implemented by the Arlequin software.

RESULTS

No independent association with these autoimmune diseases was found for either polymorphism in the Spanish cohorts tested. However, when haplotypes were compared between patients with rheumatoid arthritis and controls, a significant difference in their overall frequency distribution was observed, evidencing a protective haplotype (-168A/1614C, p = 0.006; odds ratio (OR) 0.7) and a risk haplotype (-168G/1614C, p = 0.019; OR 1.6). Patients with multiple sclerosis mirrored these results, but no effect on IBD was identified.

CONCLUSIONS

The MHC2TA gene influences predisposition to rheumatoid arthritis and multiple sclerosis, but not to IBD. The -168G allele is not an aetiological variant in itself, but a genetic marker of susceptibility/protection haplotypes.

Association of the organic cation transporter OCTN genes with Crohn's disease in the Spanish population

The SLC22A4 and SLC22A5 genes within the IBD5 risk locus encode the organic cation transporters OCTN1 and OCTN2. Two variants, 1672C>T in SLC22A4 and -207G>C in SLC22A5, were shown to alter these genes' functions and were identified as genetic susceptibility factors for Crohn's disease (CD). We pursued to check both putative etiologic variants in an independent population through a case-control study with 309 Spanish CD patients and 408 ethnically matched healthy subjects. Both polymorphisms were found in partial linkage disequilibrium (D'=0.86). The separate analysis of each OCTN variant evidenced no association. However, when the simultaneous presence of mutant variants in both genes was analyzed, an effect on CD susceptibility was observed (P=0.026, odds ratio (OR) (95% confidence interval (CI))=1.59 (1.03-2.45)). The previously described predisposition conferred by the 5q31-risk haplotype increased in the absence of the etiologic 1672T and -207C alleles (P=0.0006, OR (95% CI)=10.14 (1.97-98.04)). Moreover, the risk contributed by these polymorphisms was higher in the IBD5 wild-type population (P=0.003, OR (95% CI)=2.65 (1.32-5.35)), arguing against the exclusive etiological role of the OCTN variants. The haplotype pattern inferred led to the consideration of these variants as susceptibility markers only in a defined genetic context. Our data support the interpretation of the 1672C>T SLC22A4 and -207G>C SLC22A5 polymorphisms as genetic markers of susceptibility/protection haplotypes.

Interleukin-10 polymorphisms in Spanish IgA deficiency patients: a case-control and family study

BACKGROUND

IgA deficiency (IgAD) is the most common primary immunodeficiency in Caucasians. Genetic and environmental factors are suspected to be involved in the development of the disease. Interleukin-10 (IL-10) is a cytokine with stimulatory activity on immunoglobulin production and it may be an important regulator in IgAD pathogenesis. The IL-10 gene contains several single nucleotide polymorphisms (SNPs) and two polymorphic microsatellites located in the 5'-flanking region. Our aim was to ascertain if any of these polymorphic markers are associated or linked to IgAD in Spanish patients.

METHODS

We genotyped 278 patients with IgAD and 573 ethnically matched controls for the microsatellites IL-10R and IL-10G and for three single nucleotide polymorphisms at positions -1082, -819 and -592 in the proximal promoter of the gene. We also included in this study the parents of 194 patients in order to study the IL-10 haplotypes transmitted and not transmitted to the affected offspring.

RESULTS

The only allele where a significant difference was observed in the comparison between IgA deficiency patients and controls was the IL-10G12 allele (OR = 1.58 and p = 0.021). However, this p value could not withstand a Bonferroni correction. None of the IL-10R or promoter SNP alleles was found at a different frequency when patients were compared with controls.

CONCLUSION

Our data do not show any significant difference in IL-10 polymorphism frequencies between control and IgAD patient samples. Their haplotype distribution among patients and controls was also equivalent and therefore these microsatellites and SNPs do not seem to influence IgAD susceptibility.

Evidence for the association of the SLC22A4 and SLC22A5 genes with type 1 diabetes: a case control study

Background

Type 1 diabetes (T1D) is a chronic, autoimmune and multifactorial disease characterized by abnormal metabolism of carbohydrate and fat. Diminished carnitine plasma levels have been previously reported in T1D patients and carnitine increases the sensitivity of the cells to insulin. Polymorphisms in the carnitine transporters, encoded by the SLC22A4 and SLC22A5 genes, have been involved in susceptibility to two other autoimmune diseases, rheumatoid arthritis and Crohn's disease. For these reasons, we investigated for the first time the association with T1D of six single nucleotide polymorphisms (SNPs) mapping to these candidate genes: slc2F2, slc2F11, T306I, L503F, OCTN2-promoter and OCTN2-intron.

Methods

A case-control study was performed in the Spanish population with 295 T1D patients and 508 healthy control subjects. Maximum-likelihood haplotype frequencies were estimated by applying the Expectation-Maximization (EM) algorithm implemented by the Arlequin software.

Results

When independently analyzed, one of the tested polymorphisms in the SLC22A4 gene at 1672 showed significant association with T1D in our Spanish cohort. The overall comparison of the inferred haplotypes was significantly different between patients and controls (χ² = 10.43; p = 0.034) with one of the haplotypes showing a protective effect for T1D (rs3792876/rs1050152/rs2631367/rs274559, CCGA: OR = 0.62 (0.41–0.93); p = 0.02).

Conclusion

The haplotype distribution in the carnitine transporter locus seems to be significantly different between T1D patients and controls; however, additional studies in independent populations would allow to confirm the role of these genes in T1D risk.

Interleukin-10 haplotypes in Celiac Disease in the Spanish population

Background

Celiac disease (CD) is a chronic disorder characterized by a pathological inflammatory response after exposure to gluten in genetically susceptible individuals. The HLA complex accounts for less than half of the genetic component of the disease, and additional genes must be implicated. Interleukin-10 (IL-10) is an important regulator of mucosal immunity, and several reports have described alterations of IL-10 levels in celiac patients. The IL-10 gene is located on chromosome 1, and its promoter carries several single nucleotide polymorphisms (SNPs) and microsatellites which have been associated to production levels. Our aim was to study the role of those polymorphisms in susceptibility to CD in our population.

Methods

A case-control and a familial study were performed. Positions -1082, -819 and -592 of the IL-10 promoter were typed by TaqMan and allele specific PCR. IL10R and IL10G microsatellites were amplified with labelled primers, and they were subsequently run on an automatic sequencer. In this study 446 patients and 573 controls were included, all of them white Spaniards. Extended haplotypes encompassing microsatellites and SNPs were obtained in families and estimated in controls by the Expectation-Maximization algorithm.

Results

No significant associations after Bonferroni correction were observed in the SNPs or any of the microsatellites. Stratification by HLA-DQ2 (DQA1*0501-DQB1*02) status did not alter the results. When extended haplotypes were analyzed, no differences were apparent either.

Conclusion

The IL-10 polymorphisms studied are not associated with celiac disease. Our data suggest that the IL-10 alteration seen in patients may be more consequence than cause of the disease.

A functional PTPN22 polymorphism associated with several autoimmune diseases is not associated with IgA deficiency in the Spanish population

Background

The 1858C/T SNP of the PTPN22 gene has been associated with many autoimmune diseases, suggesting the existence of an inflammatory process common to all of them. We studied the association of that polymorphism with immunoglobulin A deficiency (IgAD) following a double approach: a case-control and a TDT study.

Methods

A total of 259 IgAD patients and 455 unrelated matched controls, and 128 families were used for each approach. Comparisons were performed using Chi-Square tests or Fisher's exact test when necessary.

Results

No association between the PTPN22 1858C/T SNP and IgA deficiency was found in any case (allelic frequencies 8% vs. 6% in patients and controls, respectively, OR= 1.14 (0.72–1.79), p= 0.56; TDT p = 0.08).

Conclusion

The result obtained seems to reinforce the consideration of IgA deficiency as a primary immunodeficiency rather than an autoimmune disease.

Severity of ulcerative colitis is associated with a polymorphism at diamine oxidase gene but not at histamine N-methyltransferase gene

AIM: To analyse the role of two common polymorphisms in genes coding for histamine metabolising enzymes as it relates to the risk to develop ulcerative colitis (UC) and the clinical course of these patients.

METHODS: A cohort of 229 unrelated patients with UC recruited from a single centre and 261 healthy volunteers were analysed for the presence of Thr105Ile and His645Asp amino acid substitutions at histamine N-methyltransferase (HNMT) and diamine oxidase (ABP1) enzymes, respectively, by amplification-restriction procedures. All patients were phenotyped and followed up for at least 2 years (mean time 11 years).

RESULTS: There were no significant differences in the distribution of ABP1 alleles between ulcerative colitis patients and healthy individuals [OR (95% CI) for variant alleles = 1.22 (0.91-1.61)]. However, mutated ABP1 alleles were present with higher frequency among the 58 patients that required immunosuppresive drugs [OR (95 % CI) for carriers of mutated alleles 2.41 (1.21-4.83; P = 0.006)], with a significant gene-dose effect (P = 0.0038). In agreement with the predominant role of ABP1 versus HNMT on local histamine metabolism in human bowel, the frequencies for carriers of HNMT genotypes or mutated alleles were similar among patients, regardless clinical evolution, and control individuals.

CONCLUSION: The His645Asp polymorphism of the histamine metabolising enzyme ABP1 is related to severity of ulcerative colitis.

Polymorphisms in interleukin-10 gene according to mutations of NOD2/CARD15 gene and relation to phenotype in Spanish patients with Crohn’s disease

AIM: To examine the contribution of interleukin-10 (IL-10) gene polymorphisms to Crohn’s disease (CD) phenotype, and the possible genetic epistasis between IL-10 gene polymorphisms and CARD15/NOD2 gene mutations.

METHODS: A cohort of 205 Spanish unrelated patients with Crohn's disease recruited from a single center was studied. All patients were rigorously phenotyped and followed-up for at least 3 years (mean time, 12.5 years). The clinical phenotype was established prior to genotyping.

RESULTS: The correlation of genotype-Vienna classification groups showed that the ileocolonic location was significantly associated with the -1082G allele in the NOD2/CARD15 mutation-positive patients (RR = 1.52, 95%CI, 1.21 to 1.91, P = 0.008). The multivariate analysis demonstrated that the IL-10 G14 microsatellite allele in the NOD2/CARD15 mutation positive patients was associated with two risk factors, history of appendectomy (RR = 2.15, 95%CI = 1.1-4.30, P = 0.001) and smoking habit at diagnosis (RR = 1.29, 95%CI = 1.04-4.3, P = 0.04).

CONCLUSION: In Spanish population from Madrid, in CD patients carrying at least one NOD2/CARD15 mutation, the -1082G allele is associated with ileocolonic disease and the IL-10G14 microsatellite allele is associated with previous history of appendectomy and smoking habit at diagnosis. These data provide further molecular evidence for a genetic basis of the clinical heterogeneity of CD.

Role of interleukin 4 in Spanish multiple sclerosis patients

Interleukin 4 is a Th2 cytokine with potent anti-inflammatory properties. Protection from autoimmune encephalomyelitis and multiple sclerosis has been achieved with IL-4 therapy and IL-4 deficient mice developed a more severe form of clinical disease. Four polymorphisms within the IL-4 gene are in strong linkage disequilibrium, including one in the promoter at -590, which controls transcriptional activity. An MS protective role for the heterozygous genotype was confirmed in Spain (exon-1+33 C/T: p=0.003, OR [CI]=0.57 [0.38-0.84]), probably indicative of an MS protection haplotype at 5q31 locus. No difference among MS clinical forms or age at onset was detected.

Early B-cell Factor gene association with multiple sclerosis in the Spanish population

Background

The etiology of multiple sclerosis (MS) is at present not fully elucidated, although it is considered to result from the interaction of environmental and genetic susceptibility factors. In this work we aimed at testing the Early B-cell Factor (EBF1) gene as a functional and positional candidate risk factor for this neurological disease. Axonal damage is a hallmark for multiple sclerosis clinical disability and EBF plays an evolutionarily conserved role in the expression of proteins essential for axonal pathfinding. Failure of B-cell differentiation was found in EBF-deficient mice and involvement of B-lymphocytes in MS has been suggested from their presence in cerebrospinal fluid and lesions of patients.

Methods

The role of the EBF1 gene in multiple sclerosis susceptibility was analyzed by performing a case-control study with 356 multiple sclerosis patients and 540 ethnically matched controls comparing the EBF1 polymorphism rs1368297 and the microsatellite D5S2038.

Results

Significant association of an EBF1-intronic polymorphism (rs1368297, A vs. T: p = 0.02; OR = 1.26 and AA vs. [TA+TT]: p = 0.02; OR = 1.39) was discovered. This association was even stronger after stratification for the well-established risk factor of multiple sclerosis in the Major Histocompatibility Complex, DRB1*1501 (AA vs. [TA+TT]: p = 0.005; OR = 1.78). A trend for association in the case-control study of another EBF1 marker, the allele 5 of the very informative microsatellite D5S2038, was corroborated by Transmission Disequilibrium Test of 53 trios (p = 0.03).

Conclusion

Our data support EBF1 gene association with MS pathogenesis in the Spanish white population. Two genetic markers within the EBF1 gene have been found associated with this neurological disease, indicative either of their causative role or that of some other polymorphism in linkage disequilibrium with them.

Polymorphisms in the transforming growth factor-beta gene (TGF-beta) and the risk of advanced alcoholic liver disease

BACKGROUND/AIMS

There are wide interindividual differences in the risk of developing alcoholic cirrhosis. Transforming growth factor beta(1) (TGF-beta(1)) is the main cytokine involved in liver fibrogenesis. The TGF-beta(1) gene is polymorphic at several sites and these polymorphisms are probably related to differences in the rate of TGF-beta(1) synthesis. Our aim has been to analyse the influence of the TGF-beta(1) gene polymorphisms in the predisposition to advanced alcoholic liver disease (ALD) in ethanol abusers.

METHODS

TGF-beta(1) single nucleotide polymorphisms at positions -509 (C or T), +869 (C or T, codon 10), and +915 (C or G, codon 25) were examined in 165 alcoholics with advanced ALD and in 185 healthy controls.

RESULTS

Among the 94 male patients with oesophageal varices, those carrying the GG genotype at position +915 were diagnosed at an older age than the remaining patients (age 52.1 years, standard deviation (SD) 9.9 vs. 45 SD 13.4, P=0.012). No other statistically significant differences were found in the distribution of the three TGF-beta(1) polymorphisms analysed individually or as combined haplotypes.

CONCLUSIONS

The polymorphisms at the TGF-beta(1) gene analysed in this study are probably not related to the risk of advanced ALD.

A recombined haplotype in the major histocompatibility region contains a cluster of genes conferring high susceptibility to ulcerative colitis in the Spanish population

BACKGROUND

The most consistently described associations in ulcerative colitis (UC) have been with human leukocyte antigen (HLA) class II alleles. Our aim was to look for associations among distinct genetic polymorphisms in the major histocompatibility complex (MHC) that might play a role in determining the susceptibility to UC and especially to the extensive form of the disease.

METHODS

A case-control study was performed with a total of 253 patients with UC and 315 healthy controls recruited from a single Spanish center. All the samples and 4 cell lines carrying DRB1*0103 or DRB1*1501 alleles were typed for the HLA-DRB1 class II gene and for a panel of HLA class III markers (D6S273, BAT_2, TNFa, b, c, d, e, IKBL+738, MICA).

RESULTS

The frequency of the alleles DRB1*0103, IKBL+738(C) (extending our previous results) and BAT_2-8 (newly typed) was increased in patients compared with controls (P=0.00001, odds ratio [OR]=5.90; P=0.002, OR=2.42; and P=0.0001, OR=3.04, respectively), and these associations were greatest in patients with extensive disease compared with patients with distal disease (P=0.02, OR=2.53; P=0.002, OR=3.06; and P=0.03, OR=2.08, respectively). The allelic combination DRB1*0103/D6S273-5/BAT_2-8/TNFa11b4c1d3e3/IKBL+738(C)/MICA5.1 that includes the telomeric class III markers of the 7.1 ancestral haplotype is highly increased in patients with UC (P=0.0001, OR=10.57), especially in those with the extensive form of the disease (P=0.02, OR=3.41 extensive versus distal).

CONCLUSIONS

The above-mentioned pattern, most likely formed by recombination of the telomeric fragment of the MHC 7.1 ancestral haplotype, seems to be the most important genetic determinant of susceptibility to the extensive form of UC in our population.

Interleukin-10 polymorphisms in Spanish patients with IBD

BACKGROUND

Inflammatory bowel disease (IBD) is considered a heterogeneous, complex polygenic disease where both genetic and environmental factors are involved in the development of the disease. Interleukin-10 (IL-10) is a regulatory cytokine that might play an important role in disease pathogenesis. IL-10 contains single nucleotide polymorphisms and 2 polymorphic microsatellites in the 5'-flanking region. Our aim was to ascertain if any of these polymorphic markers is associated with IBD among Spanish patients.

METHODS

We genotyped 470 patients with IBD, 242 with ulcerative colitis and 228 with Crohn's disease (CD), and 572 ethnically matched controls for microsatellites IL-10R and IL-10G and 2 single nucleotide polymorphisms at positions -1082 and -819 in the proximal promoter of the gene.

RESULTS

IL-10G14 microsatellite allele as well as -1082G allele were significantly increased in patients with CD. The combined presence of both alleles in 1 individual notably increased the risk to develop CD (P = 0.00006, odds ratio = 3.18).

CONCLUSION

IL-10 polymorphisms contribute to susceptibility to CD in Spanish population.

C1858T Functional Variant of PTPN22 Gene Is Not Associated With Celiac Disease Genetic Predisposition

Recent findings have demonstrated that the single nucleotide polymorphism 1858C-->T located at the P1 motif of the PTPN22 (protein tyrosine phosphatase nonreceptor 22) gene has functional relevance and is associated with a variety of autoimmune diseases. The aim of this study was to assess the role of the PTPN22 1858C-->T polymorphism in the genetic predisposition to celiac disease (CD). We analyzed a case-control cohort composed by 534 patients with CD and 653 healthy controls and additionally a panel of 271 celiac families. The PTPN22 1858C-->T genotyping was performed by TaqMan 5' allelic discrimination assay. We did not observed any statistically significant deviation after comparing allele and genotypic frequencies of PTPN22 1858C-->T between patients with CD and controls. Accordingly, the familial analysis did not reach statistically significant deviation in the transmission of PTPN22 1858C-->T alleles to the affected offspring. Therefore, our data suggest that the PTPN22 1858 single nucleotide polymorphism has no, or only a negligible, effect on CD susceptibility in this Spanish population.

Type 1 diabetes in the Spanish population: additional factors to class II HLA-DR3 and -DR4

Background

The Major Histocompatibility Complex is the main genetic contributor to susceptibility to type 1 diabetes (T1D); genome-wide scans have consistently mapped increased predisposition to this region. The highest disease risk has been associated with HLA-DR3 and HLA-DR4. In particular, the DR3-positive ancestral haplotype 18.2 was reported as highly diabetogenic. We aimed to corroborate whether this haplotype increases the susceptibility conferred by the DQ2-DR3 alleles in a Mediterranean population. We also searched for additional susceptibility factors to the classic DQ2-DR3 and DQ8-DR4.

Results

Genetic MHC markers were analysed in a case-control study with 302 T1D patients and 529 ethnically matched controls. DR3-TNFa1b5 carrier rate was significantly higher in DR3-positive heterozygous T1D patients than in DR3-positive heterozygous controls (p = 0.0019; odds ratio OR [95% confidence interval CI] = 2.26 [1.3–3.93]). This data was confirmed analysing the allelic frequency, which includes the information corresponding to the DR3-homozygous individuals (p = 0.001; OR = 2.09) and by using the Arlequin software to check the DR3-positive haplotypes (p = 0.004;OR = 1.93). The present results provide strong evidence of a second susceptibility region in the ancestral haplotype 18.2 in the Spanish population.

Moreover, we searched for T1D susceptibility factors in addition to the MHC classical ones, within the DR2-DQ6/DR3-DQ2/DR4-DQ8 negative population. Several genetic markers in both MHC class II (DQA1*0101-DQB1*0501 [p = 0.007;OR = 2.81], DQA1*0201-DQB1*0202 [p = 0.03; OR = 2.35]) and III (TNFa2b1 [p = 0.01 OR = 2.74], BAT-2*2 [p = 0.004; OR = 3.19]) were found. These different alleles associated with T1D were not independent and we observed linkage disequilibrium among them leading us to describe two new risk haplotypes (DQA1*0101-DQB1*0501-TNFa2b1 and DQA1*0201-DQB1*0202- BAT-2*2). Finally, we studied a T1D susceptibility/protection marker located in extended class I, D6S2223; however, no association was observed in our population.

Conclusion

Our results suggest that other associated MHC haplotypes might present susceptibility factors in loci different from HLA-class II and that the class II molecules are not necessarily the universal etiologic factor in every MHC haplotype.

IBD1 and IBD3 determine location of Crohn's disease in the Spanish population

BACKGROUND

Crohn's disease is a heterogeneous disease from both genetic and clinical points of view.

AIMS

To look for associations between distinct genetic polymorphisms and clinical subgroups of the disease.

SUBJECTS

A total of 210 patients and 343 healthy control subjects, all adult, unrelated, white, Spanish individuals.

METHODS

DNA was purified from peripheral blood samples and was typed by sequence-specific oligonucleotide polymerase chain reaction (PCR) method for human leukocyte antigen (HLA)-DRB1 alleles (IBD3) and by allele-specific PCR for NOD2/CARD15 (IBD1) polymorphisms.

RESULTS

NOD2/CARD15 mutations and HLA-DRB1*07 confer susceptibility only to the ileal location of the disease, whereas HLA-DRB1*0103 is associated only with the colonic location of the disease. The IBD3 effect was overshadowed by IBD1 mutations when present.

CONCLUSION

The studied genetic polymorphisms of Crohn's disease basically determine the location of the disease and, only secondarily, the clinical form of the disease. This appears to be true for both inflammatory bowel diseases as HLA-DRB1*0103 is associated both with colonic Crohn's disease and ulcerative colitis.