Alfonso Martínez

EPIDEMIOLOGIC AND CLINICAL CHARACTERISTICS OF CHILDREN WITH NEWLY DIAGNOSED INFLAMMATORY BOWEL DISEASE IN WISCONSIN: A STATEWIDE POPULATION-BASED STUDY

OBJECTIVE To define epidemiologic and clinical characteristics of newly diagnosed pediatric inflammatory bowel disease (IBD) in a large population-based model. STUDY DESIGN All pediatric gastroenterologists providing care for Wisconsin children voluntarily identified all new cases of IBD during a 2-year period. Demographic and clinical data were sent to a central registry prospectively for analysis. RESULTS The incidence of IBD in Wisconsin children was 7.05 per 100,000, whereas the incidence for Crohns disease was 4.56, more than twice the rate of ulcerative colitis (2.14). An equal IBD incidence occurred among all ethnic groups, and children from sparsely and densely populated counties were equally affected. The majority (89%) of new IBD diagnoses were nonfamilial. CONCLUSIONS This study provides novel, prospective, and comprehensive information on pediatric IBD incidence within the United States. The surprisingly high incidence of pediatric IBD, the predominance of Crohns disease over ulcerative colitis, the low frequency of patients with a family history, the equal distribution of IBD among all racial and ethnic groups, and the lack of a modulatory effect of urbanization on IBD incidence collectively suggest that the clinical spectrum of IBD is still evolving and point to environmental factors contributing to the pathogenesis.

Infliximab retreatment in adults and children with Crohn's disease: risk factors for the development of delayed severe systemic reaction.

Infliximab retreatment in adults and children with Crohns disease: risk factors for the development of delayed severe systemic reaction

MDR1 gene: susceptibility in Spanish Crohn's disease and ulcerative colitis patients.

Background: The multidrug resistance MDR1 gene codes for a membrane transporter associated with inflammatory bowel disease. The polymorphism Ala893Ser/Thr (G2677T/A) previously showed significant association with Crohns disease (CD) and the Ile1145Ile (C3435T) with ulcerative colitis (UC). We studied the association of both polymorphisms in an independent population to reveal the impact of the MDR1 gene on predisposition to inflammatory bowel disease. Methods: Case‐control study with 321 CD and 330 UC white Spanish patients recruited from the same center, and 352 healthy ethnically matched controls. Results: A significant association of MDR1 C3435T with CD was observed (CC vs (CT + TT): P = 0.007; OR [95% CI] = 1.58 [1.12‐2.23]). A CD susceptibility haplotype 2677T/C3435 was identified. No difference between UC patients as a whole and controls could be detected. Conclusions: New evidence supports the role of the MDR1 gene on CD susceptibility. Therefore, considering our results and those from others, the MDR1 gene behaves as a common risk factor for both CD and UC. We discovered that the C3435 allele conferring susceptibility to CD is different from the described 3435T UC risk allele.

MHC Susceptibility Genes to IgA Deficiency Are Located in Different Regions on Different HLA Haplotypes

Familial predisposition to IgA deficiency (IgAD) suggests that genetic factors influence susceptibility. Most studies support a polygenic inheritance with a susceptibility locus (designated IGAD1) in the MHC, but its exact location is still controversial. This study aimed to map the predisposing IGAD1 locus (or loci) within the MHC by investigating the pattern of association of the disease with several markers in the region. DNA-based techniques were used to type individual alleles of four polymorphic HLA genes (HLA-DR, -DQA1, -DQB1, and HLA-B), six microsatellites (all located between HLA-DR and HLA-B), and three single nucleotide polymorphisms on the TNF gene. The frequencies of these alleles were compared among ethnically matched populations comprising 182 patients and 343 controls. Additionally, we investigated parents and siblings of 100 of these patients. All four parental haplotypes were established in each family (n = 400), and transmission disequilibrium tests were performed. Surprisingly, our results did not support the hypothesis of a unique susceptibility gene being shared by all MHC susceptibility haplotypes. On HLA-DR1 and -DR7-positive haplotypes IGAD1 mapped to the class II region, whereas on haplotypes carrying HLA-DR3 the susceptibility locus mapped to the telomeric end of the class III region, as reported previously. Our results show how, in complex diseases, individuals may be affected for different genetic reasons and a single linkage signal to a region of a chromosome may actually be the result of disease-predisposing alleles in different linked genes in different pedigrees.

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 Crohns 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.

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.

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 Crohns 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; χ2 = 10.84). Among UC patients a significant difference was seen between those with extensive colitis and controls (P = 0.004; χ2 = 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. (Inflamm Bowel Dis 2007)

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.

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

BackgroundThe 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.MethodsA 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.ResultsWe 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.ConclusionOur 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.

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 Crohns 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; ORM-H (95% CI)=1.49 (1.17–1.90); NOD2− CD patients vs controls: P=0.0007; ORM-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.