HLA-DR and -DQ phenotypes in inflammatory bowel disease: a meta-analysis

Proteomic analysis of the inflamed intestinal mucosa reveals distinctive immune response profiles in Crohn's disease and ulcerative colitis

Although Crohn's disease (CrD) and ulcerative colitis (UC) share several clinical features, the mechanisms of tissue injury differ. Because the global cellular function depends upon the protein network environment as a whole, we explored changes in the distribution and association of mucosal proteins to define key events involved in disease pathogenesis. Endoscopic biopsies were taken from CrD, UC, and control colonic mucosa, and Multi-Epitope-Ligand-Cartographie immunofluorescence microscopy with 32 different Abs was performed. Multi-Epitope-Ligand-Cartographie is a novel, highly multiplexed robotic imaging technology which allows integrating cell biology and biomathematical tools to visualize dozens of proteins simultaneously in a structurally intact cell or tissue. In CrD, the number of CD3+CD45RA+ naive T cells was markedly increased, but only activated memory, but not naive, T cells expressed decreased levels of Bax, active caspase-3 or -8. In UC, only CD4+ T cells coexpressing NF-kappaB were caspase-8 and poly(ADP-ribose)-polymerase positive. Furthermore, the number of CD4+CD25+ T cells was elevated only in UC, whereas in CrD and controls, the number of these cells was similar. By using hub analysis, we also identified that the colocalization pattern with NF-kappaB+ and poly(ADP-ribose)-polymerase+ as base motifs distinguished CrD from UC. High-content proteomic analysis of the intestinal mucosa demonstrated for the first time that different T cell populations within the intestinal mucosa express proteins translating distinct biological functions in each form of inflammatory bowel disease. Thus, topological proteomic analysis may help to unravel the pathogenesis of inflammatory bowel disease by defining distinct immunopathogenic profiles in CrD and UC.

Genes, diet and inflammatory bowel disease

Inflammatory bowel disease (IBD) arises in part from a genetic predisposition, through the inheritance of a number of contributory genetic polymorphisms. These variant forms of genes may be associated with an abnormal response to normal luminal bacteria. A consistent observation across most populations is that any of three polymorphisms of the Caspase-activated recruitment domain (CARD15) gene are more prevalent in IBD patients as compared with unaffected controls. Similar aberrant responses to bacteria are associated with variants in Autophagy-related 16-like 1 (ATG16L1) and human defensin (HBD-2, -3 and -4) genes. The defective bacterial signal in turn leads to an excessive immune response, presenting as chronic gut inflammation in susceptible individuals. Inconsistent population reports implicate the major histocompatability complex (MHC), that encodes a number of human leukocyte antigens (HLA), MHC class I chain-related gene A (MICA) or cytokines, such as tumour necrosis factor-alpha (TNF-alpha). Toll-like receptors encoded by the TLR4 or TLR9 genes may also play a role. Recent whole genome scans suggest that a rare variant in the interleukin-23 receptor (IL23R) gene may actually protect against IBD. Other implicated genes may affect mucosal cell polarity (Drosophila discs large homologue 5, DLG5) or mucosal transporter function (sodium dependent organic cation transporters, SLC22A4 and SLC22A5). A variant in ABCB1 (ATP-binding cassette subfamily B member 1) may be especially associated with increased risk of UC. While pharmacogenetics is increasingly being used to predict and optimise clinical response to therapy, nutrigenetics may have even greater potential. In many cases, IBD can be controlled through prescribing an elemental diet, which appears to act through modulating cytokine response and changing the gut microbiota. More generally, no single group of dietary items is beneficial or detrimental to all patients, and elimination diets have been used to individualise dietary requirements. However, recognising the nature of the genes involved may suggest a more strategic approach. Pro- or prebiotics will directly influence the microbial flora, while immunonutrition, including omega-3 fatty acids and certain polyphenols, may reduce the symptoms of gut inflammation. The expression of gut transporters may be modulated through various herbal remedies including green tea polyphenols. Such approaches would require that the gene of interest is functioning normally, other than its expression being up or down-regulated. However, new approaches are being developed to overcome the effects of polymorphisms that affect the function of a gene. A combination of human correlation studies with experimental models could provide a rational strategy for optimising nutrigenetic approaches to IBD.

Inflammatory bowel disease genetics: Nod2

The inflammatory bowel diseases (IBD) are comprised of two major subphenotypes, Crohn's disease (CD) and ulcerative colitis (UC). A significant role for genetic factors in IBD was established from epidemiologic studies and, more recently, the identification of well-established disease associations, notably the association of Nod2 (CARD15) polymorphisms with CD. The mapping to CD of Nod2 variants that alter protein function represents one of the earliest, most well-established, associations in complex genetic disorders. Since the initial discovery, genotype-phenotype correlations, definition of Nod2 expression and signaling pathways, association studies in other, related disorders, and features of Nod2 deficiency in murine models have been reported. Taken together, the Nod2 association to CD provides an illustrative model of the role of single gene variants in disease pathogenesis for common, complex multigenic disorders. Here we review general aspects of IBD genetics with particular focus on the role of Nod2 in CD.

Different HLA class II associations in ulcerative colitis patients with and without primary sclerosing cholangitis

Approximately 80% of patients with primary sclerosing cholangitis (PSC) of Northern European origin have inflammatory bowel disease (IBD), the majority ulcerative colitis (UC). An inherent problem in interpreting positive findings in genetic association studies of PSC is thus to distinguish between factors associated with hepatobiliary versus intestinal pathology. We aimed to clarify to what extent human leukocyte antigen (HLA) class II associations in UC patients with and without PSC differ. High-resolution DRB1 and DQB1 typing was performed in 365 Scandinavian PSC patients, an independent cohort of 330 Norwegian UC patients and 368 healthy controls. HLA associations found in PSC were mostly distinct from those seen in UC, and no significant differences were noted between PSC patients with concurrent UC and PSC patients without IBD. This suggests different HLA associated genetic susceptibility to PSC and UC, and supports notions that UC in PSC may represent a distinct UC phenotype.

Molecular pathogenesis of inflammatory bowel disease: genotypes, phenotypes and personalized medicine

Crohn's disease (CD) and ulcerative colitis (UC), also known as inflammatory bowel diseases (IBD), are characterized by chronic inflammation of the gastrointestinal tract. IBD is among the few complex diseases for which several genomic regions and specific genes have been identified and confirmed in multiple replication studies. We will review the different loci implicated in disease risk in the context of three proposed mechanisms leading to chronic inflammation of the gut mucosa: 1) deregulation of the innate immune response to enteric microflora or pathogens; 2) increased permeability across the epithelial barrier; and 3) defective regulation of the adaptive immune system. As our knowledge of genetic variation, analytical approaches and technology improves, additional genetic risk factors are expected to be identified. With the identification of novel risk variants, additional pathophysiological mechanisms are likely to emerge. The resulting discoveries will further our molecular understanding of IBD, potentially leading to improved disease classification and rational drug design. Moreover, these approaches and tools can be applied in the context of variable drug response with the goal of providing more personalized clinical management of patients with IBD.

Review article: genetic susceptibility and application of genetic testing in clinical management of inflammatory bowel disease

The volume of research undertaken on the genetic susceptibility of inflammatory bowel disease (IBD) has been tremendous, and over 10 chromosomal regions have been identified by genome-wide scanning. Fine-mapping approaches and candidate gene studies have already led to the identification of several susceptibility genes, including CARD15 (NOD2), DLG5, novel organic cation transporter (OCTN) 1 and 2, and CARD4 (NOD1). The CARD15 gene is the most understood at present and explains around 20% of the genetic predisposition to Crohn's disease. Although the clinical implications of genetic testing are limited at present, genetic research has advanced our understanding of the clinical heterogeneity and the complex interactions between genetic and environmental risk factors in IBD. Genes also interfere with the metabolism of drugs and may influence the clinical response and drug-related toxicity. Ultimately, researchers and clinicians aim to personalize medicine based on a patient's genotype, although azathioprine (thiopurine methyltransferase polymorphisms) is the only drug to date where pharmacogenetics has shown clinical relevance in IBD. In the future, it is anticipated that genetic markers will be implemented in an integrated molecular diagnostic and prognostic approach to managing our patients.

Genetic variants and the risk of Crohn's disease: what does it mean for future disease management?

Genetic research in inflammatory bowel disease, especially in Crohn's disease, has made significant progress during recent years. There have been > 10 total genome scans that have been performed, and susceptibility loci on several chromosomes have been identified. Together with candidate gene studies, these scans have led to the identification of several susceptibility genes, with CARD15 being the most important. These genetic data have already provided important insights into the pathophysiology of inflammatory bowel disease and are stimulating future research. On the other hand, genotype-phenotype associations have illustrated the heterogenic nature of the disease. Although the clinical application of this knowledge is so far limited, there is significant optimism that an individual management of patients based on genetic data will be possible in the near future.

Genetics of inflammatory bowel disease: The role of the HLA complex

The human leucocyte antigen (HLA) complex on chromosome 6p21.3 is the most extensively studied genetic region in Inflammatory bowel disease (IBD). Consistent evidence of linkage to IBD3 (6p21.1-23), an area which encompasses the HLA complex, has been demonstrated for both Crohn’s disease and ulcerative colitis, and a number of replicated associations with disease susceptibility and phenotype have recently emerged. However, despite these efforts the HLA susceptibility gene (s) for IBD remain elusive, a consequence of strong linkage disequilibrium, extensive polymorphism and high gene density across this region. This article reviews current knowledge of the role of HLA complex genes in IBD susceptibility and phenotype, and discusses the factors currently limiting the translation of this knowledge to clinical practice.

Genetic advances in inflammatory bowel disease

The translation of basic science advances to tangible benefits in clinical practice remains a fundamental goal of biomedical research. Genetic approaches provide a unique opportunity to enhance bench-to-bedside translational efforts, with inflammatory bowel disease (IBD) being a model genetic disorder in several respects. The association of the NOD2 (CARD15) mutations to Crohn's disease (CD) represents, in complex human disorders, one of the clearest cases of a definitive disease association. The NOD2 gene is located in the IBD1 genetic linkage region on chromosome 16 and functions as an intracellular pattern recognition receptor for components of bacterial peptidoglycan. CD-associated variants within NOD2 have a decreased capacity to appropriately signal with peptidoglycan and provide an important example of gene-environment interactions. Genetic variation in other innate immune receptors, notably Toll-like receptor (TLR)4, has been defined and may also play a role in CD pathogenesis. Replicated CD association in the IBD5 region on chromosome 5q has been reported, and candidate functional polymorphisms within the organic cation transporters OCTN1 (SLC22A4) and OCTN2 (SLC22A5) have been described. Confirmatory studies demonstrating altered OCTN activity and expression in primary human cells stratified on the IBD5 risk haplotype would provide important confirmatory support for disease contribution. A comprehensive understanding of IBD will involve integrating information from animal models, functional human polymorphisms, and expression studies from human IBD tissues. Genes and pathways implicated as contributing to IBD pathogenesis through multiple lines of evidence should be more intensively examined, including the tumor necrosis factor-alpha, MDR1, and peroxisome proliferator-activated receptor (PPAR)gamma pathways. To attain full advantage of new genetic information, novel methods of classifying patients that go beyond phenotypic classifications presently utilized will be required. Genetic data will need to be integrated with novel biomarker development in IBD, including functional, expression (mRNA or protein), or biochemical indicators of physiologic/disease processes and responses to therapies.

TNF-857 polymorphism in Israeli Jewish patients with inflammatory bowel disease

Tumour necrosis factor (TNF)-alpha is an important pro-inflammatory cytokine that has been implicated in the pathogenesis of inflammatory bowel disease (IBD). The promoter TNF-857 C-->T single nucleotide polymorphism (SNP) is functional through the binding to the transcription factor octamer transcription factor-1 (OCT-1). In order to investigate the frequency of this SNP in Israeli Jewish IBD patients, we analysed a cohort of well-characterized patients, 153 with Crohn's disease (CD) and 78 with ulcerative colitis (UC) and 188 healthy controls individually matched for age, sex and ethnicity. Forty-one per cent of the patients were of Ashkenazi and 48% were of non-Ashkenazi background. The remaining 11% were of mixed Ashkenazi-non-Ashkenazi background. Patients and controls were genotyped for the TNF-857 SNP by Taqman technology. Stratification for the CARD15 Arg702Trp, Gly908Arg and Leu1007fsinsC mutations took place in 136 CD patients. Carrier frequency of TNF-857T between CD and controls (36% vs. 40%; P = 0.556; OR: 1.18, 95% CI 0.74-1.88), or between UC and controls (41% vs. 37%; P = 0.743; OR: 0.85, 95% CI 0.45-1.62) did not differ significantly. Neither did stratifying for the presence of at least one of the common CARD15 mutations result in a significant difference between CD and controls. No associations were found between TNF-857T and CD phenotype as defined by the Vienna classification, perianal disease or extra-intestinal disease irrespective of CARD15 carrier status. In conclusion, it appears that TNF-857 SNP does not contribute to susceptibility of IBD, neither does it define the phenotype of CD in Israeli Jewish IBD patients.

Advances in the molecular dissection of inflammatory bowel disease

Recent advances in the field of inflammatory bowel disease (IBD) genetics have enabled the definition and refinement of multiple IBD susceptibility loci and the identification of gene variants within such regions showing association with Crohn's disease (CD) and/or ulcerative colitis (UC). Most notable among the newly defined genetic determinants of IBD are specific variants in the CARD15 gene, which have been shown widely to influence both susceptibility and phenotype in CD. These genetic data have inspired intensive studies of CARD15 biologic functions and the information emerging from these analyses has already substantively enhanced understanding of the signaling pathways coupling bacterial pathogens to the host immune response. Genetic data implicating various other signaling effectors in IBD susceptibility have similarly focused attention on the molecular pathways driven or regulated by these proteins and the biochemical events linking effector/pathway dysfunction to intestinal inflammation and disease. In this review, progress in defining the genetic determinants of IBD is described with an emphasis on the impact of such knowledge on understanding of IBD molecular pathophysiology.

The role of inflammatory bowel disease susceptibility loci in multiple sclerosis and systemic lupus erythematosus

To date, three loci have been validated to confer susceptibility to inflammatory bowel disease (IBD): the CARD15/NOD2 gene, the discs large homolog 5 gene (DLG5), and the IBD5 locus on 5q31 (IBD5). We have explored the possibility that these loci may also be associated with susceptibility to two other chronic inflammatory diseases, multiple sclerosis (MS) and systemic lupus erythematosus (SLE). As the CARD15 risk alleles had previously been assessed in our collection of 496 MS trios, we focused our efforts on the DLG5 risk allele and the IBD5(risk) haplotype (IBD5(risk)) for MS. While there is no evidence of association within our MS sample with either of these polymorphisms, screening of 1027 subjects with SLE suggests that IBD5(risk) may have a modest contribution to disease risk in the subset of SLE subjects without lupus nephritis. In addition, a pooled analysis of existing published and unpublished data in 1305 cases of SLE genotyped for the CARD15 risk alleles suggests that only the CARD15(908R) IBD risk allele may have a strong effect on risk of SLE. Our data, therefore, suggest that both the CARD15 gene and the IBD5 locus may have a role as general susceptibility loci for certain common, genetically complex inflammatory diseases.

New genes in inflammatory bowel disease: lessons for complex diseases?

The chronic inflammatory bowel diseases Crohn's disease and ulcerative colitis are common causes of gastrointestinal disease in northern Europe, affecting as many as one in 250 people. Although mortality is low, morbidity associated with these diseases is substantial. We review the recent advances in the genetics of inflammatory bowel disease, with particular emphasis on the data that have been generated since the discovery of the CARD15 (NOD2) gene in 2001.

HLA-DRB1 Alleles and Cervical Squamous Cell Carcinoma: Experimental Study and Meta-Analysis

Polymorphisms in human leukocyte antigen (HLA) genes have been implicated in the risk for cervical cancer. Association of certain class II HLA alleles with cervical cancer has been documented in various ethnic populations. The implications of such an association, however, are controversial. We analyzed 126 Chinese women with cervical squamous cell carcinoma (CSCC) and 289 healthy controls to test associations of certain HLA-DRB1 alleles. We then performed meta-analyses combining our own experimental data and data from nine other published studies. We found no significant differences in HLA-DRB1 allele frequencies in both CSCC and HPV-16-positive CSCC patients and control subjects. Meta-analysis provided evidence that four allele families (HLA-DRB1*04, *07, *11, and *15) and seven alleles (HLA-DRB1*0403, *0405, *0407, *0701, *1501, *1502, and *1503) were positively associated and two allele families (HLA-DRB1*09 and *13) and four alleles (HLA-DRB1*0901, *1301, *1302, and *1602) were negatively associated with CSCC in all studies or in Caucasian subgroups. In conclusion, our meta-analysis confirms the apparent association between certain HLA-DRB1 allele families and alleles and CSCC, suggesting that oncogenesis in this disease may be related to defects in immunoregulation. Larger studies may be needed, particularly in various ethnic groups, to further substantiate these associations.

Polymorphism of HLA-DRB1 gene shows no strong association with ulcerative colitis in Chinese patients

The genetic factors predisposing to ulcerative colitis (UC) have remained totally unclear to date. This study aimed to investigate the role of HLA-DRB1 genetic polymorphism in the susceptibility to develop UC in Chinese patients. HLA-DRB1 genotyping was carried out in 72 unrelated patients with UC and 314 healthy controls by using polymerase chain reaction-sequence-specific primers (PCR-SSP). All of the patients and healthy controls are Han people in China. The frequency of DRB1*07 allele was increased in UC patients compared with healthy controls (19.4% vs. 9.2%, P = 0.0229, OR = 2.372, 95%CI: 1.181-4.766), but the significance disappeared when given Bonferroni correction (P(C) = 0.2977). Furthermore, compared with healthy controls, although HLA-DRB1*07, DRB1*16/DRB1*09 and DRB1*07/DRB1*12 genotypes were increased in frequency in the patients with extensive colitis, and the patients without extraintestinal manifestations (EIMs) carried an increased frequency of HLA-DRB1*07 and DRB1*07/DRB1*12 genotypes, these differences did not reach statistical significance after Bonferroni correction. HLA-DRB1 alleles showed no strong association with UC, and no HLA-DRB1 alleles or genotypes were strongly associated with clinical subgroups of UC in Chinese patients.

Environment as a Critical Factor for the Pathogenesis and Outcome of Gastrointestinal Disease: Experimental and Human Inflammatory Bowel Disease and Helicobacter-Induced Gastritis

Environmental factors play an important role in the manifestation, course, and prognosis of diseases of the gastrointestinal tract such as inflammatory bowel disease (IBD) and Helicobacter pylori-induced gastritis. These two disease complexes were chosen for a discussion of the contribution of environmental factors to the disease outcome in humans and animal models. Dissecting complex diseases like IBD and Helicobacter-induced gastritis has shown that the outcome of disease depends on the allelic constellation of a host and the microbial and physical environments. Host alleles predisposing to a disease in one genomic and/or environmental milieu may not be deleterious in other constellations; on the other hand, microbes can have different effects in different hosts and under different environmental conditions. The impact of the complex interaction between host genetics and environmental factors, particularly microflora, also underlines the importance of a defined genetic background and defined environments in animal studies and is indicative of the difficulties in analyzing complex diseases in humans.

Current concept on the pathogenesis of inflammatory bowel disease-crosstalk between genetic and microbial factors: Pathogenic bacteria and altered bacterial sensing or changes in mucosal integrity take “toll”

The pathogenesis of inflammatory bowel disease (IBD) is only partially understood. Various environmental and host (e.g. genetic-, epithelial-, immune and non-immune) factors are involved. It is a multifactorial polygenic disease with probable genetic heterogeneity. Some genes are associated with IBD itself, while others increase the risk of ulcerative colitis (UC) or Crohn’s disease (CD) or are associated with disease location and/or behaviour. This review addresses recent advances in the genetics of IBD. The article discusses the current information on the crosstalk between microbial and genetic factors (e.g. NOD2/CARD15, SLC22A46A5 and DLG5). The genetic data acquired in recent years help in understanding the pathogenesis of IBD and can identify a number of potential targets for therapeutic intervention. In the future, genetics may help more accurately diagnose and predict disease course in IBD.

Recent advances in the etiology and treatment of inflammatory bowel disease

Crohn's disease and ulcerative colitis, together comprising the inflammatory bowel diseases, currently affect up to 2 million people in the western developed countries. The pathogenesis of the disease is a complex one in which genetic, immunogenic, microbial and environmental factors contribute to the etiology of the disease. Recent advances in understanding the molecular mechanisms that determine this complex entity have provided insight for promising new therapies.

Early and frequent histological recurrence of Crohn's disease in small intestinal allografts

BACKGROUND

Recurrence of Crohn's disease in small intestinal allografts, although rarely described, can cause serious morbidity and jeopardize graft survival among transplant recipients with Crohn's disease. However, systematic studies to determine the frequency, predictors, and clinical implications of recurrent Crohn's disease have not been reported

METHODS

We analyzed our transplant program's experience with small intestinal allografts in patients with Crohn's disease based on retrospective review of clinical and pathological records and corresponding pathology slides.

RESULTS

Of 67 patients undergoing 70 transplantations between 1998 and 2004, six adults (three males, three females; mean age 48.1 years) had Crohn's disease complicated by short gut syndrome and total parenteral nutrition failure. Four survivors surveyed endoscopically for a mean 29 (range, 20-40) months and underwent a mean 37 endoscopic examinations with biopsies (range, 31-44) while on maintenance immunosuppression. Despite absence of any endoscopic or clinical manifestations of Crohn's disease throughout this period, two patients had granulomatous enteritis characteristic of Crohn's disease in multiple biopsies, one patient in 8/44 examinations (18%) ranging from 34 days to 20 months postoperatively and the other in 6/32 examinations (19%) ranging from 20 days to 22 months postoperatively. No comparable changes occurred in 57 other patients without Crohn's disease followed endoscopically under the same protocol

CONCLUSIONS

Histological recurrence of Crohn's disease may occur in small intestinal allografts despite the absence of endoscopic and clinical disease manifestations. Such recurrences are probably not rare, may occur as early as 3 weeks after transplantation, and do not necessarily portend early clinical recurrence or mandate aggressive therapy to prevent allograft loss.

Current status of genetics research in inflammatory bowel disease

The research on genetic susceptibility of inflammatory bowel diseases (IBD) has been tremendous and over 10 chromosomal regions have been identified by genome-wide scanning. Further fine mapping as well as candidate gene studies have already led to the identification of a number of susceptibility genes including CARD15, DLG5, OCTN1 and 2, NOD1, HLA, and TLR4. The CARD15 gene is undoubtedly replicated most widely and most understood at present. CARD15 is involved in the recognition of bacterial peptidoglycan-derived muramyl dipeptide (MDP) and will stimulate secretion of antimicrobial peptides including alpha-defensins (also called cryptdins) to protect the host from invasion. Genetic research in IBD has advanced our understanding of the clinical heterogeneity of the disease and has started to tackle the complex interactions between genetic risk factors and environmental risk factors in IBD. Genes also interfere with the metabolization of drugs and may influence the clinical response and the drug-related toxicity. Interesting pharmacogenetic data with respect to steroids, azathioprine, and infliximab have been generated in IBD. Overall, it is anticipated that genetic markers in the future will be implemented in an integrated molecular diagnostic and prognostic approach of our patients.

Consequence of functional Nod2 and Tlr4 mutations on gene transcription in Crohn's disease patients

The concept that mutations in germ-line encoded pattern recognition receptors with immune activating functions are associated with an increased incidence in Crohn's disease (CD) is gaining acceptance. Whether these mutations have similar or distinct effects on cellular physiology remains obscure. The incidence of three single nucleotide polymorphisms (SNPs) within the Nod2 gene and one functional SNP within both the Tlr4 and Tlr5 gene in a Dutch cohort of 637 patients with inflammatory bowel disease and 127 controls was investigated. The functional consequence of mutant NOD2 and TLR4 was investigated by comparing gene expression profiles after stimulation of monocyte-derived dendritic cells (DCs) from homozygous TLR4- and NOD2-mutant patients with lipopolysaccharides and peptidoglycan, respectively. We observed that the R702W and 1007fs Nod2 alleles and the A299G Tlr4 alleles were significantly more prevalent in patients with CD as compared to healthy controls or patients with ulcerative colitis. The phenotype of TLR4- and NOD2-mutant DCs is distinct, but a large number of genes are up- or down-regulated concordantly. These data provide a concept for the genetic basis of CD; mutations in innate immunity cause similar effects on gene transcription and finally result in comparable clinical disease presentation.

Primary sclerosing cholangitis in two brothers: report of a family with special emphasis on molecular HLA and MICA genotyping

Immune mechanisms play a role in the pathogenesis of primary sclerosing cholangitis (PSC), as suggested by its association with certain HLA haplotypes. Genetic predisposition is supported by its occurrence in families, but data are scarce. Our aim is to report on two brothers with PSC, and to investigate HLA and MICA alleles in this family. The clinical, biochemical, radiological, and pathological findings in two brothers with PSC as well as in their sister and parents were reviewed. Molecular genotyping of HLA class II and MICA alleles was performed in all five family members. In two brothers, p-ANCA positive PSC was found. The youngest also had ulcerative colitis, and had evolved into cirrhosis at the age of 17 years. Their mother had positive p-ANCA and mild cholestatic changes. Their father and sister were unaffected. Both brothers were homozygous for the MICA*00801 allele, and were positive for the susceptibility HLA haplotypes DR3-DQ2 and DR6-DQ6. Their unaffected father and sister both carried the protective DR4 allele. The presence of PSC in two brothers, and the distribution of HLA haplotypes and MICA alleles, adds supportive evidence for an immunogenetic origin of PSC.

HLA-DRB1 alleles may influence disease phenotype in patients with inflammatory bowel disease: a critical reappraisal with review of the literature

PURPOSE

The HLA region has been implicated in determining the disease susceptibility or the clinical phenotype of inflammatory bowel disease. The aim of this study was to assess the relation between HLA-DRB1 alleles with the clinical features of Crohn's disease and ulcerative colitis and the presence of anti-neutrophil cytoplasmic and anti-Saccharomyces cerevisiae antibodies.

METHODS

Blood samples were obtained from 102 Crohn's disease patients, 114 ulcerative colitis patients, and 264 unrelated healthy controls. Anti-neutrophil cytoplasmics were detected by a standard immunofluorescence method, and anti-Saccharomyces cerevisiaes were examined by an enzyme-linked immunosorbent assay immunoglobulin G/immunoglobulin A commercial assay. HLA-DRB1 typing of 26 alleles was performed by polymerase chain reaction sequence-specific primes. Patients were phenotyped according to gender, disease location, extent, and behavior, surgical resection, need of steroid, and anti-neutrophil cytoplasmic/anti-Saccharomyces cerevisiae status.

RESULTS

As a whole, after applying Bonferroni's correction for multiple comparisons, no significant association of HLA-DRB1 alleles with Crohn's disease or ulcerative colitis was found. After stratifying HLA-DRB1 alleles by clinical phenotypes of patients with ulcerative colitis, an excess of DRB1*1309*1320*1325*1329 allele (DR13) was found in conjunction with pancolitis (P < 0.0001), surgical resection (P < 0.0003), and extraintestinal manifestations (P < 0.0001). In Crohn's disease patients, an excess of DRB1*0304*0305*0307*0309 allele (DR3) was found in those with colonic disease (P < 0.0001) and patients with extraintestinal manifestations (P = 0.0003). This statistical association, however, emerged in only 3 of 114 patients with ulcerative colitis and in 3 of 102 patients with Crohn's disease. We found no association with the presence of anti-Saccharomyces cerevisiae or anti-neutrophil cytoplasmic.

CONCLUSIONS

Some clinical features of Crohn's disease and ulcerative colitis may be influenced by specific HLA-DR alleles; in particular, in ulcerative colitis some alleles appear to segregate with more aggressive disease, whereas in Crohn's disease different alleles cosegregate in patients with colonic disease and extraintestinal manifestations.

Advances in the genetics of inflammatory bowel disease

Research efforts in the inflammatory bowel diseases have been uniquely successful in identifying genetic linkage regions likely containing susceptibility genes for Crohn's disease and ulcerative colitis. In two of these regions, definitive gene associations have been established, namely for the NOD2/CARD15 gene on chromosome 16 (IBD1) and the OCTN1/SLC22A4-OCT/SLC22A5 genes on chromosome 5q (IBD5), both conferring increased risk for developing Crohn's disease. Recently, significant gene associations have been reported for additional genes, including DLG5, MDR1, and TLR4 as well. The NOD2/CARD15 gene mutations are associated with ileal disease location and a modestly earlier age of onset compared with NOD2/CARD15 wild-type Crohn's disease patients. Future progress in the genetics of inflammatory bowel disease will likely involve systematic phenotyping, including the incorporation of clinical subtypes and novel biomarkers. The ultimate goal of genetic research in inflammatory bowel disease is to identify the earliest biologic pathways that are altered, resulting in disease pathogenesis. Identification of these key pathways will potentially highlight novel therapeutic targets.

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.

The contribution of human leucocyte antigen complex genes to disease phenotype in ulcerative colitis

Linkage and association studies implicate the human leucocyte antigen (HLA) region in genetic susceptibility to ulcerative colitis (UC). However, associations with specific variants have been inconsistent, even within defined ethnic groups. A genetic basis for the disease heterogeneity of UC may account for these discrepant findings from studies in unselected populations. Here, we examine the contribution of the HLA region to the clinical phenotype of UC. We studied 321 accurately phenotyped patients recruited from a single UK centre, with a median follow-up time of 15 years. Individuals were genotyped for 340 polymorphisms constructed into 25 gene-specific allelic haplotypes between HLA-A and Tapasin. Data were analysed with respect to age of onset, disease extent and severity. Strongest association with overall susceptibility was identified with HLA-DRB1 alleles replicating previous studies (DRB1*0103, DRB1*1502 and DRB1*0401). We report a novel association with homozygosity of a tumour necrosis factor (TNF) promoter haplotype (TNF-1031T, -863C, -857C, -380G, -308G and -238G) and distal disease extent that does not extend with time (distal vs total 40.9 vs 25.7%; RR = 2.0; 95% CI 1.23-3.24). We confirm the association of DRB1*0103 with total disease and/or disease requiring colectomy and further demonstrate that DRB1*0103 is associated with shorter time to surgery. Genes in the HLA play a role in modifying disease phenotype. Further studies are required to dissect how these genes functionally interact with each other and with environmental factors to determine clinical patterns of disease

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The contribution of HLA genes to IBD susceptibility and phenotype

The human leukocyte antigen (HLA) region located on chromosome 6p encodes the highly polymorphic, classical class I and II genes essential for normal lymphocyte function; it also encodes a further 224 genes. Many early studies investigating this region were limited by small sample size, poor statistical methodology, population stratification and variable disease definition. Although more recent studies have improved study design, investigators are still challenged by the complex patterns of linkage disequilibrium across this gene-dense region, and by the disease heterogeneity characteristic of all genetically complex disorders. However, a number of important observations have emerged from recent studies: (1) the HLA harbours gene(s) that determine susceptibility to colonic inflammation in both ulcerative colitis (UC) and Crohn's disease (CD); (2) most of the specific associations with UC and CD appear to differ; (3) associations between different ethnic groups differ; (4) markers in the HLA might predict the course of disease and the development of complications, notably the extraintestinal manifestations of disease.

Clinical relevance of advances in genetics and pharmacogenetics of IBD

Crohn's disease and ulcerative colitis result from an inappropriate response of the mucosal immune system to the normal enteric flora in a genetically susceptible individual. During the past decade, exciting progress has been made in our understanding of the contribution of genetics to inflammatory bowel disease susceptibility and phenotype. This article reviews recent advances in the genetics of inflammatory bowel disease and explores how they might impact on clinical practice. Current knowledge of the genetic basis for disease susceptibility, phenotype, and response to therapy is explored and the factors currently limiting the translation of this knowledge to clinical practice is discussed.

Inflammatory bowel disease gene hunting by linkage analysis: rationale, methodology, and present status of the field

Observed inflammatory bowel disease (IBD) familial clustering and increased monozygotic twin concordance has led to the hypothesis that genetic loci containing IBD susceptibility genes can be identified by whole genome linkage mapping approaches. Methodology including collecting carefully phenotyped multiplex pedigrees, genotyping using highly informative microsatellite markers and linkage analysis by non-parametric allele sharing methods has been established. Eleven published genome wide screens (GWS) have studied more than 1,200 multiplex IBD pedigrees. Two-thirds of affected relative pairs were Crohn's disease (CD), 20% ulcerative colitis (UC) and the remaining were mixed. Seven loci (IBDI-7) on chromosomes 16q, 12, 6p, 14q, 5q, 19, and 1p have been identified with genome wide significant and independently replicated linkage. Risk alleles/haplotypes have been defined for the IBD1 (CARD15/NOD2), IBD3 (HLA) and IBD5 (5q cytokine cluster) loci. There has been evidence for a second chromosome 16 locus (IBD8) independent of NOD2 that overlaps IBD1 on the pericentromeric p-arm. Several other regions show great promise for containing additional IBD loci, particularly chromosome 3p with genome wide evidence in one study at 3p26 and more centromeric evidence in several other studies, and chromosomes 2q, 3q, 4q, 7, 11p, and Xp each with suggestive evidence of linkage in one and additional evidence in two or more studies. Single GWSs and fine mapping studies containing very large sets of pedigrees and in particular, more UC pedigrees, and the use of creative analytic and disease stratification schemes are required to identify, establish and refine weaker IBD loci.

CARD15 and HLA DRB1 alleles influence susceptibility and disease localization in Crohn's disease

OBJECTIVES

Crohn's disease (CD) is a chronic inflammatory disease of the gut associated with allelic variants of CARD15 and HLA-DRB1 genes. We investigated the prevalence and effects of these variants in a Canadian CD cohort.

METHODS

507 unrelated CD patients were genotyped for the three major CD-associated variants (Arg702Trp, Gly908Arg, and Leu1007fsinsC) and for thirteen HLA-DRB1 alleles.

RESULTS

At least one CARD15 variant was present in 32.5% of the CD patients compared with 20% of controls. The prevalence of CARD15 mutation was similar in both sporadic and familial and Jewish and non-Jewish CD patients. The Gly908Arg variant was significantly higher and the Arg702Trp variant significantly lower in Jewish compared to non-Jewish patients. A positive association between the HLA-DRB1*0103 allele and CD was detected in non-Jewish, familial cases (p = 0.0002), with risk for CD increased by 6.7 fold by the presence of an HLA-DRB1*0103 allele as compared to 1.9 fold and 19 fold by a single or two CARD15 variant alleles, respectively. We show a significant association of ileal involvement with CARD15 variants (OR = 1.8; p = 0.02), HLA-DRB1*0701 (OR = 1.9; p = 0.006) and DRB1*04 (OR = 1.7; p = 0.02) alleles and demonstrate the capacity of combined CARD15 and HLA-DRB1 genotyping to predict ileal disease in CD patients. By contrast, the HLA-DRB1*0103 allele was associated with later age of diagnosis (p = 0.02) and pure colonic disease (p = 0.000013).

CONCLUSIONS

These observations confirm the influence of CARD15 and HLA-DRB1 alleles on both CD susceptibility and site of disease and identify genotyping of these variants as a potential tool for improved diagnosis and risk prediction in CD.

Inflammatory bowel disease and the eye

Inflammatory bowel disease includes Crohn's disease and ulcerative colitis, and is characterized by chronic inflammation of the intestines. The advances in understanding of the inflammatory process have resulted in improved treatment of inflammatory bowel disease. The systemic complications of inflammatory bowel disease involve many organs, eyes included. The ophthalmic complications are usually of inflammatory origin. Some of these complications, like scleritis, may reflect overall disease activity. Treatment of intestinal inflammation-either medical or surgical-usually helps resolution of ophthalmic complications. This review describes recent developments in the diagnosis and management of the inflammatory bowel disease and its ophthalmic complications.

A genome scan in 260 inflammatory bowel disease-affected relative pairs

We report the results of a new genome scan in 260 IBD-affected relative pairs from 139 families that we have recruited since our previous IBD genome scans were performed. The goal of our study was to determine whether we could extend the linkage evidence in any of the more than 20 regions with nominal evidence for linkage to IBD in previous individual genome scans in order to prioritize regions for further study.

Is it time to re-classify Crohn's disease?

From the original anatomic classification of Crohn's disease in 1975, there have been three subsequent published classifications. The most recent, the Vienna Classification arose from a 1998 World Congress of Gastroenterology Working Party that attempted to prospectively design a simple and objective Crohn's disease phenotypic classification that encompassed components of age at onset, anatomic location and disease behavior. Subsequent application of the Vienna Classification to clinical practice has demonstrated that the Crohn's disease phenotype changes markedly over time, with nearly 80% of inflammatory disease ultimately evolving into a stricturing or penetrating pattern of behavior, and 15% undergoing a change in anatomic location. Furthermore, in controlled studies, the ability of inflammatory bowel disease experts to similarly identify the disease phenotypes, using the Vienna classification, ranges from poor to fair. Taken together, these failings markedly limit the utilization of the Vienna classification of Crohn's disease in clinical trails or disease management. Recent advances in determining the genetic linkages associated with Crohn's disease will undoubtedly lead to a revised Crohn's disease classification that will combine genotype with phenotype. Nevertheless, before this new classification can become a reality we will need to reconcile a number of key elements, including; (1) localization and grouping of all inflammatory bowel disease(IBD) gene mutations, (2) discovering the function of the IBD genes, (3) understanding the impact of the environment on phenotypic expression, and, (4) linking to well-defined phenotypic databases that will permit accurate prediction of disease natural history and therapeutic response. Indeed, the consistency of the phenotypic data available may be the greatest single challenge in unraveling the complexities of inflammatory bowel disease and developing a new classification of Crohn's disease.

Update on the genetics of inflammatory bowel disease

There is a general consensus that interplay of genetic and environmental factors leads to an overactive mucosal immune response, which mediates the tissue damage in inflammatory bowel disease. Ethnic aggregation of inflammatory bowel disease (particularly, increased incidence and prevalence in the Ashkenazim), familial aggregation of inflammatory bowel disease, and greater concordance for inflammatory bowel disease in monozygotic twins than dizygotic twins are 3 lines of evidence for a central role of genetic factors in the pathogenesis. The genetics of inflammatory bowel disease cannot be explained by simple Mendelian genetics; it is characterized by incomplete penetrance, multiple susceptibility loci and genetic heterogeneity. Unraveling the complex genetics of inflammatory bowel disease is a daunting challenge, but the perseverance of inflammatory bowel disease gene hunters has produced commendable results in recent years. Since 1996, the field of inflammatory bowel disease genetics has progressed from publication of the first systematic genome searches for inflammatory bowel disease susceptibility loci to the identification of Crohn disease-associated genetic variants in CARD15/NOD2. Strategies for finding additional inflammatory bowel disease genes include taking advantage of the greater resolution and power of linkage disequilibrium mapping, mapping by admixture disequilibrium in African-American and Hispanic-American populations, stratifying genetic analyses by genotypes at known inflammatory bowel disease loci, and refining inflammatory bowel disease phenotypes to reduce genetic heterogeneity and simplify the search for additional inflammatory bowel disease genes.

Progress in searching for susceptibility gene for inflammatory bowel disease by positional cloning

Inflammatory bowel disease (IBD) includes two clinical subtypes: Crohn disease (CD) and ulcerative colitis (UC). The general prevalence is about 1.0%-2.0% in Western countries. It is predominantly regarded as a multifactorial disorder involving environmental factors and polygenic defects. The view was confirmed by a lot of evidences from clinical attributions and animal models, especially from epidemiological investigations. So the etiological study of IBD has been focused on searching for susceptibility genes by positional cloning, which consists of two steps: linkage analysis and association analysis. Linkage analysis has been an important method of searching for susceptibility genes to polygenic diseases as well as single-gene disorders. IBD, as a polygenic disease, has been widely investigated by linkage analysis for susceptibility gene since 1996. The paper reviewed 38 articles, which covered almost all original researches in relation to IBD and linkage analysis. So far, several loci, such as 16q, 12q, 6p and 3p, have been identified by the studies. The most striking is 16q12 (IBD1), which linked only with CD not UC in the majority of studies. Association analysis, as one essential step for positional cloning, is usually carried out by genotyping candidate genes selected by means of linkage analysis or other methods, for figuring out the frequencies of alleles and comparing the frequencies between IBD group and healthy control group to identify the specific allele. It has been established that IBD is implicated in immune disorder. So the studies were centered on the genes of NOD2/CARD15, HLA-II, cytokine, cytokine receptor and adhesion molecule. This paper reviewed 14 original articles on association between NOD2 and IBD that have been published since 2001. All results, with the exception of one report from a Japanese group, provide evidences that the three kinds of variants of NOD2 are susceptibility factors for IBD. This article also comprehensively analyzed 18 original researches of HLA gene polymorphism in IBD. We found extensive discrepancy among the conclusions and a novel hypothesis was put forward to explain the discordance. Most studies published recently on association between IBD and cytokine gene polymorphism were reviewed.

Genotype-based phenotyping heralds a new taxonomy for inflammatory bowel disease

Inflammatory bowel disease (IBD) has traditionally been categorized as either ulcerative colitis or Crohn disease on the basis of clinical, radiologic, and histologic criteria. Within these diseases, however, significant heterogeneity is observed, suggesting the existence of phenotypic subtypes, based on features such as location and behavior of disease. Evidence for a possible genetic basis of these subgroups first emerged in the 1990s from epidemiologic studies in multiply affected families. Recent advances in our understanding of the genetics of IBD, in particular the identification of NOD2/CARD15, have provided the opportunity to explore the genetic basis for this heterogeneity. This article reviews recent studies investigating the contribution of genetics to IBD phenotype. Although many of the genes remain unidentified, the emerging data suggests that IBD comprises a heterogeneous family of oligogenic inflammatory disorders in which the specific clinical manifestations of disease in any individual are determined by the interaction of genetic and environmental factors. These data have validated the approach of classifying patients into accurately defined clinical subgroups, and they raise the possibility that a genetic basis for the observed disease heterogeneity may account for the discrepant findings from earlier genetic studies. A future molecular classification will provide the framework to understanding the different biologic mechanisms that underlie the clinical subgroups of IBD and, by patient stratification, permit the unraveling of the complex interaction between the genetic and environmental causes of disease.

Granulocyte and monocyte adsorption apheresis in a patient with antiglomerular basement membrane glomerulonephritis and active ulcerative colitis

A 58-year-old woman with Goodpasture syndrome and active ulcerative colitis is described. On admission, the patient had exertional dyspnea, hemoptysis, severe hypertension, and peripheral edema. Her serum levels of urea nitrogen and creatinine were increased, and her hemoglobin concentration was reduced. The patient had a rapidly progressive glomerulonephritis with acute renal failure. She was treated with methylprednisolone, cyclophosphamide, and plasmapheresis but failed to regain renal function. Circulating anti-glomerular basement membrane (anti-GBM) antibody was positive; however, serum antinuclear antibody, proteinase-3-antineutrophil cytoplasm antibody and myeloperoxidase-antineutrophil cytoplasm antibody were negative. Nineteen months after initial presentation, she developed abdominal pain and severe diarrhea. These symptoms did not improve with conventional treatment. Colonoscopy performed after 3 months showed multiple ulcers in the colon. She was diagnosed with ulcerative colitis. She underwent granulocyte and monocyte adsorption apheresis once per week for 5 weeks. At 8 weeks, her symptoms had improved; her stool number was markedly decreased, and the bloody stools and abdominal pain disappeared. These results suggest that granulocyte and monocyte apheresis may be of benefit in the therapy of a patient with ulcerative colitis who previously had Goodpasture syndrome

The 4G/4G genotype of the 4G/5G polymorphism of the type-1 plasminogen activator inhibitor (PAI-1) gene is a determinant of penetrating behaviour in patients with Crohn's disease

BACKGROUND

Crohn's disease is a heterogeneous disorder with polygenic inheritance.

AIM

To assess the effect of the 4G/5G polymorphism of the type-1 plasminogen activator inhibitor (PAI-1) gene, the major inhibitor of fibrinolysis, on Crohn's disease susceptibility and phenotype.

METHODS

One hundred and fifty-seven patients with Crohn's disease and 350 controls were included prospectively. Medical records were reviewed to determine changes in the Crohn's disease phenotype. The 4G/5G polymorphism was assessed by polymerase chain reaction techniques.

RESULTS

The frequencies of the 4G/4G, 4G/5G and 5G/5G genotypes were similar in patients with Crohn's disease and controls. The 4G/4G genotype (P < 0.0001; odds ratio, 4.84) and male sex (P = 0.009; odds ratio, 2.63) were independent risk factors for penetrating behaviour in Crohn's disease. Most Crohn's disease patients had a non-penetrating phenotype at diagnosis. The probability of development of a penetrating phenotype within 5 years of diagnosis was higher in patients with the 4G/4G genotype (72% vs. 19%, P < 0.0001).

CONCLUSIONS

The 4G/4G genotype of the PAI-1 gene does not influence Crohn's disease susceptibility, but increases by five-fold the probability of penetrating behaviour. Most patients with the 4G/4G genotype have a non-penetrating phenotype at diagnosis, but develop a penetrating behaviour within 5 years. Genotyping the 4G/5G polymorphism may be useful for the identification of a sub-group of patients with aggressive Crohn's disease, who might benefit from specific therapy.

Genetics of inflammatory bowel disease: scientific and clinical implications

Considerable progress has been made in the last decade in studies of the genetics of the inflammatory bowel diseases, Crohn's disease and ulcerative colitis. Epidemiological data, notably concordance rates in twin pairs and sibling pairs, have provided strong evidence for the importance of the genetic contribution, particularly in Crohn's disease. These observations provided the catalyst for laboratory-based studies of the molecular genetics of Crohn's disease and ulcerative colitis around the world. The complementary strategies of genome-wide scanning and candidate gene-directed studies have led to the identification of a number of genetic markers which appear to predict disease susceptibility and behaviour. The identification of the IBD1 gene on chromosome 16 as NOD-2 is unquestionably an important scientific discovery. Although many issues with respect to gene function and expression remain to be resolved there is great optimism that important clinical applications will directly result.

A population- and family-based study of Canadian families reveals association of HLA DRB1*0103 with colonic involvement in inflammatory bowel disease

The aim of this study was to identify major histocompatibility complex alleles associated with the development and clinical features of inflammatory bowel disease (IBD). Genotyping at the human leukocyte antigen (HLA) DRB1 and DQB1 loci was performed on individuals from 118 Caucasian IBD sibling pair families and on 216 healthy controls. Both population- and family-based association tests were used to analyze data obtained on the entire study population and on clinical subgroups stratified by diagnosis, ethnicity, and disease distribution. HLA DRB1*0103 was significantly associated with IBD (OR = 6.0, p = 0.0001) in a case-control analysis of non-Jewish IBD-affected individuals. This association was apparent among both Crohn's disease (OR = 5.23, p = 0.0007) and ulcerative colitis (OR = 7.9, p = 0.0001) patients and was confirmed in the non-Jewish IBD population by results of family-based association analysis using the transmission disequilibrium test. HLA DQB1*0501 was also associated with IBD (OR = 1.64, p = 0.02) in the non-Jewish population. but statistically significant association of this allele with disease was not detected for Crohn's disease and ulcerative colitis separately. No significant associations were identified among the Jewish patients. In the non-Jewish IBD families, IBD was as strongly associated with the DRB1*0103 DQB1*0501 haplotype as with the DRB1*0103 allele alone. The carrier frequency of the DRB1*0103 allele was found to be 10-fold higher in Crohn's disease patients with pure colonic involvement than in healthy controls (38.5% vs. 3.2%; p = 0.0002). These data demonstrate the association of the HLA DRB1*0103 allele with both Crohn's disease and ulcerative colitis and with large intestine-restricted disease in non-Jewish IBD patients and therefore identify HLA DRB1*0103 as a potentially important contributor to disease susceptibility and to expression of colonic involvement in IBD.

Clinical and genetic heterogeneity in Mexican patients with ulcerative colitis

Ulcerative colitis (UC) is an inflammatory bowel disease of unknown etiology. Genetic factors implied on its onset and severity may include genes located within the class II major histocompatibility complex (MHC) region. The aim of this study was to determine the relationship between human leukocyte antigen (HLA)-DRB1 alleles with the clinical disease patterns of UC in Mexican Mestizo patients. High-resolution HLA typing was performed by polymerase chain reaction-sequence specific oligonucleotide (PCR)-SSO reverse dot blot and PCR-single-strand polymorphism in 67 patients with UC and 99 ethnically matched healthy controls. UC patients overall showed an increased frequency of HLA-DR1 as compared with healthy controls (17.1% versus 5%, [pC = 0.003, OR = 3.9]). Patients with extensive colitis showed increased frequencies of HLA-DR1 (pC = 1 x 10(-10), OR = 13.9), HLA-DRB1*0103 (pC = 1 x 10(-3), OR = 21.7), HLA-DRB1*0102 (pC = 0.007, OR = undetermined), and HLA-DR15 (pC = 1 x 10(-3), OR = 8.5) when compared with healthy controls. We also found a statistically increased frequency of HLA-DR15 in UC patients with extensive colitis compared with UC patients with only distal colitis (18.7% versus 1.8%, pC = 0.03; OR = 12.2). When patients who underwent proctocolectomy were compared with those who did not, an increased frequency of HLA-DRB1*0103 was observed (21.8% versus 4.9%; pC = 0.03; OR = 5.4; 95% confidence interval, 1.39-21.93). Also, patients with proctocolectomy showed increased frequencies of HLA-DR1 (pC = 1 x 10(-3), OR = 24.2) and HLA-DRB1*0103 (pC = 1 x 10(-3), OR = 50.6) when compared with healthy controls. We concluded that HLA-DR1 is associated with genetic susceptibility to UC in the Mexican Mestizo population. HLA-DR15 distinguishes a subgroup of patients with extensive colitis and the HLA-DRB1*0103 allele distinguishes a subgroup of severe form of disease that might require surgical management.

The genetic jigsaw of inflammatory bowel disease

Following a prolonged period of relative inertia, real progress has been made in the past few years in understanding the pathogenesis of the chronic inflammatory bowel diseases, Crohn's disease and ulcerative colitis. Clinical experience, epidemiological studies, and molecular genetics have provided strong evidence that both genetic and environmental factors are important in disease pathogenesis, and gene-environmental interaction determines disease susceptibility and behaviour.

[Development of inflammatory bowel disease in a husband and wife]

It is currently thought that chronic inflammatory bowel disease (IBD) may be due to the action of an as-yet unidentified external agent on genetically predisposed individuals. While genetic influence on the development of the disease has been widely studied, very little is known about the possible environmental agents that could influence its development. One example of the influence of environmental agents could be the development of chronic IBD in a husband and wife. We describe the case of a married couple; after more than 30 years of cohabitation, the wife developed fistulizing Crohn's disease and, 7 years later, the husband developed ulcerative proctosigmoiditis. Currently, approximately 70 cases have been described in the international literature but none have been reported in Spain. We discuss the characteristics of our patients compared with those described in published reports and stress the importance of describing these cases for the future identification of a possible external agent.

The molecular classification of the clinical manifestations of Crohn's disease

BACKGROUND & AIMS

Crohn's disease is a common inflammatory disorder of the gut characterized by variation in both location and behavior. Chromosome 16 and the HLA region on chromosome 6 have been implicated in susceptibility to disease. Mutations in the NOD2/CARD15 gene, recently identified on chromosome 16, have been associated with disease overall but are found in only 25% of patients. No data regarding their contribution to specific disease subtypes exist. Here we report a detailed genotype-phenotype analysis of 244 accurately characterized patients.

METHODS

A total of 244 white patients with Crohn's disease recruited from a single center in the United Kingdom were studied. All patients were rigorously phenotyped and followed-up for a median time of 16 years. By using linkage disequilibrium mapping we studied 340 polymorphisms in 24 HLA genes and 3 NOD2/CARD15 polymorphisms.

RESULTS

We show that NOD2/CARD15 mutations determine ileal disease only. We confirm that alleles on specific long-range HLA haplotypes determine overall susceptibility and describe novel genetic associations with susceptibility, location, and behavior of Crohn's disease.

CONCLUSIONS

The clinical pattern of Crohn's disease may be defined by specific genotypes. This study may provide the basis for a future molecular classification of disease.