Search

Chromosomal region 2q33 encodes the immune regulatory genes, CTLA4, ICOS and CD28, which are involved in regulation of T-cell activity and has been studied as a candidate gene locus in autoimmune diseases, including coeliac disease (CD). We have investigated whether an association exists between this region and CD in the Irish population using a comprehensive analysis for genetic variation. Using a haplotype-tagging approach, this gene cluster was investigated for disease association in a case–control study comprising 394 CD patients and 421 ethnically matched healthy controls. Several SNPs, including CTLA4_CT60, showed association with disease; however, after correction for multiple-testing, CTLA4−658C/T was the only polymorphism found to show significant association with disease when allele, genotype, or carrier status frequency were analysed (carrier status (Allele C), P=0.0016). Haplotype analysis revealed a haplotype incorporating the CD28/CTLA4 and two 5′ ICOS polymorphisms to be significantly associated with disease (patients 24.1%; controls 31.5%; P=0.035), as was a shorter haplotype composed of the CTLA4 markers only (30.9 vs 34.9%; P=0.042). The extended haplotype incorporating CD28/CTLA4 and 5′ ICOS is more strongly associated with disease than haplotypes of individual genes. This suggests a causal variant associated with this haplotype may be associated with disease in this population.Genes and Immunity (2006) 7, 19–26. doi:10.1038/sj.gene.6364265; published online 20 October 2005 [ABSTRACT FROM AUTHOR]

Genetic predisposition to coeliac disease (CD) is determined primarily by alleles at the HLA-DQB locus, and evidence exists implicating other major histocompatibility complex-linked genes (6p21) and the CTLA4 locus on chromosome 2q33. In addition, extensive family studies have provided strong, reproducible evidence for a susceptibility locus on chromosome 5q (CELIAC2). However, the gene responsible has not been identified. We have assayed genetic variation at the IL4, IL5, IL9, IL13, IL17B and NR3C1 (GR) loci, all of which are present on chromosome 5q and have potential or demonstrated involvement in autoimmune and/or inflammatory disease, in a sample of 409 CD cases and 355 controls. Thirteen single nucleotide polymorphisms were chosen on the basis of functional relevance, prior disease association and, where possible, prior knowledge of the haplotype variation present in European populations. There were no statistically significant allele or haplotype frequency differences between cases and controls. Therefore, these results provide no evidence that these loci are associated with CD in this sample population.

Background: HLA-DR2 (15) and 14 (6) have been recently proposed as susceptibility alleles for the development of sarcoidosis and HLA-DR15 as a marker of poor outcome, but validation in other populations is necessary., Methods: Employing serological techniques, we HLA-typed 103 Irish sarcoidosis patients and 105 ethnically-matched healthy controls for class I A and B and II DR and DQ alleles., Results: HLA-B5 (10% vs. 2%, p = 0.018) and DR2 (45% vs. 27%, p = 0.007) were positively associated and B15 (0% vs. 7%, p = 0.01) negatively associated with sarcoidosis compared to control subjects. Seventy-five patients were followed > 2 years and 47 (63%) had chronic and 28 (37%) non-chronic disease. HLA-DR2 (55% vs. 27%, p = 0.001) and DR11 (26% vs. 5%, p<0.0001) were significantly more frequent in chronic disease vs. controls, in contrast to HLA-DR3 (13% vs. 38%, p = 0.002), which had a significant negative association. HLA-B5 (11% vs. 2%, p = 0.029) and DR3 (64% vs. 38%, p = 0.005) were significantly more frequent in non-chronic disease. Of the 29 patients achieving spontaneous remission, 24 (83%) were HLA-DR3 -positive and DR3-positivity was associated with significantly greater carbon monoxide diffusion at follow-up compared to DR3-negative patients (90% vs. 82% predicted, p = 0.027)., Conclusions: This study supports the role of HLA-DR2 (15) as both a susceptibility and poor prognostic marker in sarcoidosis and DR2 positive patients may particularly benefit from close follow-up and early treatment. In contrast, DR3 positive patients are at a much lesser risk of chronic disease. Studies for long-term treatment effects require stratification for HLA-DR2 and DR3 status.

In addition to the well-established association of coeliac disease (CD) with HLA-DQ (6p21) and possibly CTLA4 (2q33), there is considerable evidence for a susceptibility locus on chromosome 5q, which contains many potential candidates for inflammatory disease, including a cluster of cytokine genes in 5q31. CD cases and controls were genotyped for four single-nucleotide polymorphism (SNP) markers that together characterize >90% of the haplotype variation at the IBD5 locus encoding, among others, the SLC22A4 gene. IBD5 and SLC22A4 map to 5q31 and have recently been associated with Crohn's disease and rheumatoid arthritis. Haplotype frequencies do not differ significantly between CD cases and controls in the Irish population, and therefore the chromosome 5 CD susceptibility locus most likely lies elsewhere on 5q.

Celiac disease is a strongly heritable gastrointestinal illness that is an especially important model of the genetically complex multifactorial immune mediated diseases. The HLA component of celiac disease (a specific HLA-DQ heterodimer)is largely established and is relatively uncomplicated, and the environmental component (gluten and related grain storage proteins in the diet) is remarkably well understood. Previous family studies of celiac disease suggested that there is at least one important non-HLA locus. This locus may be a stronger genetic factor than HLA, and it apparently has a recessive mode of inheritance. We used a three step genome screening protocol to identify loci that contribute to celiac disease in the western counties of ireland, a region with the highest prevalence of celiac disease in the world. The most significant of several possible non-HLA loci that we found was on chromosome 6p about 30 cM telomeric from HLA. It has a multipoint maximum lod score of 4.66 (compared with 4.44 for HLA-DQ) and appears to have a recessive mode of inheritance. Our study localizes and provides strong evidence for linkage of at least one non-HLA locus to celiac disease and may serve as a prototype for an efficient approach to screening the human genome for loci that contribute to complex diseases.

Background: The ability to secrete blood group antigens into body fluids and secretions is controlled by a single gene on chromosome 19. By means of erythrocyte Lewis (Le) antigen phenotype secretor status can be inferred. An increase prevalence of non-secretors of blood group antigens among coeliac patients has recently been described., Methods: Blood was collected from 112 coeliac patients and 103 controls and tested for secretor status. Secretor status was correlated with human leucocyte antigens (HLA) in coeliac patients, thus evaluating a proposed interaction of susceptibility genes--that is, the secretor gene on chromosome 19 and HLA-linked genes on chromosome 6. Case notes for coeliacs were reviewed with regard to clinical outcome., Results: Of 112 coeliacs who had either Le(a) or Le(b) antigens, 36 (32%) were non-secretors Le(a+, b-), compared with 27% (28) of 103 disease-free controls (P = 0.313). Recessive Lewis phenotype Le(a-, b-) was found in 9% of coeliacs versus 2% of controls. Prevalence of HLA-A1, B8, DR3, and DQ2 was unrelated to secretor status in coeliac versus patients. An increased prevalence of complications and coeliac-associated abnormalities was found in the non-secreting and recessive coeliac groups., Conclusions: This study shows no firm relationship between the non-secretor state and coeliac disease, nor any difference in the distribution of HLA markers among secretor and non-secretor coeliacs. It is unlikely, therefore, that the secretor gene is the much sought-after second coeliac gene.

Celiac disease (CD) has one of the strongest class II HLA associations of any human illness. We used DNA-RFLP typing to study the class II HLA genotypes of celiac disease patients from the West of Ireland, the geographic area with the highest rate of celiac disease in the world. We confirmed the high frequency of HLA-DR3 in this population, and we were also able to demonstrate the additional risk of developing celiac disease imparted by HLA-DR7. This was done by clearly distinguishing DR7,DQ2 haplotypes from DR7,DQ9 haplotypes, and by "subtraction analysis" of haplotype frequencies. As reported in other populations, most of the patients without DR3 were heterozygous for DR7 and DR11 or 12 (DR5), or had DR4. We used PCR-RFLP and direct sequencing of amplified DNA to examine HLA-DR4 subtypes. The frequency of HLA-DR4 was markedly decreased in patients compared with controls (p = 0.000001) and there was a significant alteration of DR4 subtypes of the patients compared with controls (p = 0.0227). Moreover, all of the CD patients (5 of 5) with DR4 had a haplotype associated with the DQB1*0302 allele compared with only 11 of 23 control subjects with DR4. Our results in this population with exceptionally high risk of CD strongly support the DQ heterodimer hypothesis and suggest that the recently described sequence difference between the DQB1*02 alleles of DR3 and DR7 may contribute to a synergistic increased risk when these haplotypes are inherited together. In addition, our findings suggest a role for HLA-DQ in DR4-associated CD.

Although celiac disease has one of the strongest human lymphocyte antigen (HLA) class II associations of any human illness, it is clear that at least one gene that is not linked to the HLA region also is required for its pathogenesis. The occurrence of large numbers of gamma delta T cells in the bowel mucosa of patients and the recent description of T cell receptor (TCR) gamma chain polymorphic variants identified by restriction fragment length polymorphism analysis led the authors to examine TCR gamma genotypes in relation to HLA-DR, DQ genotypes in 89 patients with celiac disease and 55 control subjects from the West of Ireland. The overall frequency of TCR gamma genotypes in patients and control subjects was comparable. However, most of the patients had 1 of 3 HLA-DR3 genotypes (DR3/15, 3/7, or 3/3), and there was a significant alteration of the expected frequency of TCR gamma genotypes among patients with these three genotypes. The major differences were an increased association of HLA-DR3 homozygosity, with TCR gamma genotypes having a 16.0 kb fragment and an increased frequency of DR3/7 heterozygosity and decreased frequency of DR3/15 heterozygosity, respectively, in association with the TCR gamma 13.0/11.3 kb genotype. Based on their results, there is the possibility that an interaction between the products of two polymorphic and unlinked gene regions contributes to the pathogenesis of celiac disease.

alpha 1 antitrypsin or protease inhibitor (Pi) phenotyping was carried out on 111 coeliac disease patients (CD) and 250 controls. The Pi MM phenotype was present in 95 (85.6%) of the coeliacs and 225 (90%) of the controls. The groups did not differ significantly with regard to Pi phenotypes. In the CD group the Pi Phenotype did not relate to HLA B8 or DR3 status. Associated diseases in the CD patients did not correlate with Pi phenotype.

The highest reported prevalence of celiac disease (gluten-sensitive enteropathy) is found in the West of Ireland. Recent genetic data have suggested that major histocompatibility complex-linked loci may have a dominant genetic effect for disease susceptibility in this population compared with a recessive effect in other groups. To further understand the role of the MHC in celiac disease in the West of Ireland, we analyzed markers for 22 MHC haplotypes from celiac patients and compared them with 18 nontransmitted haplotypes found in the parents of celiac children, and with reported haplotypes from other populations. An extended MHC haplotype including [HLA-B8, DR3, DQw2, Bf*S, C4A*Q0, and C4B*1] accounted for 50% of celiac haplotypes but only 27% of nontransmitted parental haplotypes. Compared with other reported haplotypes in celiacs, patients from the West of Ireland show a higher prevalence of HLA-A1 as a component of this extended haplotype, suggesting that although the core haplotype is similar between Irish patients and others, the celiac population in the West of Ireland differs at other HLA loci. We did not observe any other common haplotypes among our patients unlike the situation in other populations. These differences may underlie the possible dominant effect of HLA-linked loci and the unusually high prevalence of celiac disease in the Irish population. We also found that the serum levels of complement components C3c, C4, and factor B were significantly lower among celiac patients than nonceliacs. The lower serum level of C4 appears to be related to the presence of deletions and null alleles at the C4A and C4B loci in celiacs.

Restriction fragment length polymorphism analysis, using a single restriction enzyme TaqI-multiple-probe system for HLA-DRB1-DQB1 and -DQA1, was used to determine HLA-DR and -DQ frequencies in 56 unrelated celiac patients and 47 unrelated controls from the west of Ireland. In addition, HLA-DPB1 allelic frequencies were determined in the same group of patients and controls by using the technique of enzymatic DNA amplification of the polymorphic second exon of HLA-DPB1 genes in conjunction with sequence-specific oligonucleotide probing. The results suggest that HLA-DQ rather than HLA-DR is more important in conferring susceptibility to celiac disease. Furthermore, no association between HLA-DP and celiac disease was found in this study.

A two gene model has been proposed to explain the inheritance of coeliac disease (CD). One gene is on chromosome 6 in the MHC complex (HLA associated). It has been suggested the second gene is located on chromosome 14, in or near the region encoding for immunoglobulin heavy chain allotypes (Gm types). In a study of 102 unrelated Irish coeliacs and a group of ethnic controls, we have failed to show an association of CD with any particular Gm type or types. There is no evidence to confirm that a gene on chromosome 14 is implicated in the inheritance of CD.

Although coeliac disease (CD) is strongly associated with the HLA alleles B8 and DR3, the genetic basis of this illness remains obscure. Recent studies show that at least two unlinked loci are involved. Most studies agree on recessivity at the HLA-unlinked locus but differ with respect to dominance or recessivity at the HLA-linked disease susceptibility locus. To address this controversy, we examined the association of CD with HLA in 39 families from the West of Ireland. Previous studies have shown that the prevalence of CD and the frequencies of the HLA antigens associated with it are higher in this population than in most others. Analysis of the data revealed a significant excess of concordant sib-pairs with two HLA haplotypes in common and an excess of discordant pairs with no haplotype in common. Chi-square tests confirmed a highly significant association between HLA-B8 and CD. Both heterozygotes and homozygotes for B8 had a significantly increased risk of CD. The risk for homozygotes was slightly higher than for heterozygotes, although not significantly so. The segregation ratio for disease occurrence among sibs of probands was estimated to be 0.185 when neither parent is affected. We estimated a gene frequency of 0.003 for the disease allele (C) at the HLA-linked locus and of 0.648 for the disease allele (d) at the HLA-unlinked locus. Assuming that CCdd homozygotes are always affected and that only carriers of C who are homozygous dd can be affected, the disease was found to be completely penetrant in Ccdd heterozygotes. These results support dominance at the HLA-linked locus conferring susceptibility to CD. Possible reasons for the discrepancy between the West of Ireland and other populations are discussed.

HLA, A, B, and DR typing was done on seven of 10 patients with lymphoma, and six patients with carcinoma, all of whom had a flat small intestinal mucosa. Sixty-nine per cent (nine of 13) had HLA B8 and 71% (five of seven) had DR3. The corresponding levels for the local coeliac population are 76% and 84% respectively and the local non-coeliac population 43% and 44%. Two of the patients with lymphoma had a child with coeliac disease. The histological type of the lymphoma was malignant histiocytosis of the intestine in seven, histiocytic lymphoma in two, and was not classifiable in one. The similarity of the HLA type suggests that the flat mucosa in both groups is due to coeliac disease.

Between 1960 and 1974 the incidence of coeliac disease in children under 12 years in County Galway remained fairly constant, but since 1975 it has fallen by 62% and the lowered incidence seems well established. The number of those who were breast fed and the age at which first gluten feeding took place during the 22 years both increased significantly and from the mid-70s total protein content and osmolarity of proprietary cow's milk formulas were reduced. All three factors may be relevant. A negative correlation with the incidence of gastroenteritis was found.

Tissue typing (HLA-A, -B and -DR) was carried out on 92 patients with coeliac disease (CD) and on a further 71 first degree relatives of 13 of these patients. Results of antigen frequencies in unrelated patients and segregation analysis in families shows that HLA-DR3 but not HLA-DR7 is positively associated with CD. Haplotype and sib-pair data from these coeliac families suggest that with all of them, genetic susceptibility to CD lies in the HLA region of the sixth chromosome. In families where the coeliac proband has HLA-DR3, the relative risk to siblings who also have this antigen is increased 35 times.

The results of endoscopic examination, biopsy taken at endoscopy and cytology of brush smears and/or gastric lavage specimens in 100 patients with proven malignant gastric lesions are described. Overall, a correct pre-operative diagnosis was achieved in 98 cases. Endoscopic appearance was a more accurate criterion in cases of exophytic advanced carcinoma, malignant ulcer and lymphoma than in diffuse infiltrative carcinoma or in early carcinoma, where biopsy and cytology were more accurate. Nine per cent of neoplasms were malignant lymphomas, which is much higher than the usual reported incidence. Early carcinoma was found in 5% of cases. In spite of readily available facilities for endoscopic diagnosis, most cases of gastric neoplasm were already advanced at the time of examination.