Search for coeliac disease susceptibility loci on 7q11.23 candidate region: absence of association with the ELN17 microsatellite marker

Williams-Beuren Syndrome and celiac disease: A real association?

Celiac disease (CD) screening in patients with Williams-Beuren Syndrome (WBS) is suggested, although data described in literature are discordant regarding CD prevalence in WBS. We retrospectively collected data from 101 WBS Italian patients [mean age: 13.5 years], to clarify the CD prevalence in a large cohort. All patients underwent a CD biochemical screening: IgA and anti-transglutaminase reflex antibodies (tTGA). CD-specific HLA typing was available for 42 patients. Small intestinal biopsy was performed in patients according to ESPGHAN guidelines. In 7 WBS patients an overt celiac disease was diagnosed. In 3 patients CD was confirmed by symptoms, HLA-DQ heterodimers and CD specific antibodies title, whereas in 4 patients, it was confirmed by a small intestinal biopsy. CD prevalence in our cohort is 6.9% (7/101). In 42/101 patients the CD-specific HLA typing was available, detecting 29/42 (69%) patients genetically predisposed to CD. The CD prevalence and CD-specific HLA prevalence are both higher than in the general population (p < 0.001; p < 0.001). Our cohort is the most numerous described confirming that the CD risk in WBS patients is significantly greater than in general population. Moreover, our HLA typing results, as well as scientific literature, suggest that the higher CD prevalence in WBS patients might not be intrinsically related to the genetic disease itself but with the higher HLA prevalence. However, HLA typing should be performed in bigger WBS cohorts to confirm this hypothesis. Our data confirms that HLA typing is mandatory in WBS patients and that CD screening should be performed only if genetically predisposed.

Coeliac disease and risk for other autoimmune diseases in patients with Williams-Beuren syndrome

BACKGROUND

A higher prevalence of coeliac disease (CD) has been reported in patients with Williams-Beuren syndrome (WBS), though coexistence with other autoimmune diseases has not been evaluated.

OBJECTIVE

The aim of this study was to examine the prevalence of the more frequent autoimmune diseases and organ- and non-organ specific autoantibodies in WBS.

METHODS

We longitudinally analysed 46 WBS patients to evaluate the prevalence and co-occurrence of the major autoantibodies and HLA typing for CD diagnosis. These data were compared with healthy age- and sex-matched controls and Down (DS) and Turner (TS) syndrome patients.

RESULTS

CD was diagnosed in one (2.2%) WBS patient; this differed significantly from DS and TS (respectively, 10.5% and 9.4%; P < 0.005) but not from healthy controls (0.6%; P = NS). However, no patients with WBS showed anti-thyroid antibodies or other organ- and non-organ specific autoantibodies, which differed significantly from DS (respectively, 10.5% and 7.0%; P < 0.005) and TS (respectively, 9.4% and 9.3%; P < 0.005) patients but not from healthy controls (1.1% and 2.3%). The frequencies of CD-specific HLA-DQ heterodimers were not significantly higher than controls, even though the WBS patients more frequently carried the DQA1*0505 allele (57% vs. 39%; P < 0.05).

CONCLUSIONS

CD may not be more frequent in patients with WBS. In fact, no evidence of a significantly higher prevalence of other autoimmune diseases or positivity of the main organ and non-organ specific autoantibodies was found in WBS, such as showed in the healthy controls and unlike by the patients with Turner or Down syndrome. This should prompt us to better understand the occurrence of CD in WBS. Other studies or longer follow-up might be useful to clarify this issue.

Clinical management of coeliac disease

OBJECTIVE

To describe the prevalence of Coeliac disease (CD) and its clinical management.

METHODS

Narrative review.

RESULTS

Coeliac disease (CD) is an immune-mediated disorder that primarily affects the gastrointestinal (GI) tract. Recent data suggest a prevalence of about 1% in most Western countries, a figure that likely represents an increase in the prevalence of CD. Risk groups include those who are members of families with individuals who have CD as well as those with Type I diabetes and a variety of autoimmune diseases. Whereas biopsy is the gold standard in diagnosis, serological tests are crucial in determining who should undergo endoscopy and biopsy. HLA testing should be used only to rule out CD. Currently, a gluten-free diet is the only available therapy.

CONCLUSION

In conclusion, CD is one of the most common immune-mediated disorders in the Western world. It should be considered in patients with a number of varying GI and non-GI symptoms, as well as in high-risk groups that include first-degree relatives.

The pathogenesis of coeliac disease

Coeliac disease is a common condition and its prevalence in UK is now thought to be approximately 1:100. It is being diagnosed and treated more frequently as awareness at the primary care level has increased. Coeliac disease is a complex disorder and is frequently associated with other disease processes. The management of these patients needs to take on a holistic approach, whilst the physician needs to be aware of the rare complications. This article gives an up-to-date review of the literature written on the pathogenesis of coeliac disease. We have attempted to paint a picture from beginning to end, whilst clarifying the grey areas in between. General epidemiological factors are reviewed before looking at genetic risk factors. We assess the sensitivity and specificity of the investigative modalities available for clinical use and comment on optimum management of these patients thereafter. The future of coeliac disease looks promising for patients with several novel therapies on the horizon. Whilst further work is still needed to breed out the toxic epitopes from wheat, novel therapies may come from other areas such as the work aimed at restoring normal tolerance to gluten.

Genomewide linkage analysis of celiac disease in Finnish families

Celiac disease (CD), or gluten-sensitive enteropathy, is a common multifactorial disorder resulting from intolerance to cereal prolamins. The only established genetic susceptibility factor is HLA-DQ, which appears to explain only part of the overall genetic risk. We performed a genomewide scan of CD in 60 Finnish families. In addition to strong evidence for linkage to the HLA region at 6p21.3 (Z(max)>5), suggestive evidence for linkage was found for six other chromosomal regions--1p36, 4p15, 5q31, 7q21, 9p21-23, and 16q12. We further analyzed the three most convincing regions--4p15, 5q31, and 7q21--by evaluation of dense marker arrays across each region and by analysis of an additional 38 families. Although multipoint analysis with dense markers provided supportive evidence (multipoint LOD scores 3.25 at 4p15, 1.49 at 5q31, and 1.04 at 7q21) for the initial findings, the additional 38 families did not strengthen evidence for linkage. The role that HLA-DQ plays was studied in more detail by analysis of DQB1 alleles in all 98 families. All but one patient carried one or two HLA-DQ risk alleles, and 65% of HLA-DQ2 carriers were affected. Our study indicates that the HLA region harbors a predominant CD-susceptibility locus in these Finnish families.

Genetic factors underlying gluten-sensitive enteropathy

Genetic epidemiology clearly has shown that there is a genetic predisposition to gluten-sensitive enteropathy (GSE), or celiac disease. The strong genetic component, as determined by the lambda sib (lambda s), has been calculated to lie in the range of 7.5 to 30, based on a 5% to 10% recurrence risk for siblings. Ninety-five percent of northern European patients with GSE carry a particular HLA-DQ alpha beta heterodimer. Studies support the concept that the HLA-DQ gene acts as a dominant gene, and they also found that, in addition to HLA-DQ, a second locus within the major histocompatibility complex (MHC) is involved in the predisposition to GSE in the Dutch population. Genome scans conducted so far suggest that MHC and non-MHC loci collectively contribute to disease susceptibility. Since one, and probably even two, gene(s) from the MHC region itself determine at least 40% to 50% of the genetic predisposition to GSE, it is expected that the other loci each contribute only a little to the total genetic variation. The exact role of these additional genes (i.e., whether they are involved in the initiation or the progression of the disease) remains to be determined.

Celiac disease

Celiac disease is more prevalent than it was previously thought to be, and screening of selected population groups may reveal many new cases. Tissue transglutaminase appears to have a significant role in the degradation of gliadin and antigen production. Specific gliadin epitopes have been defined using T-cell responses. Bone disease is a significant problem for patients with celiac disease but management guidelines are being developed. Refractory sprue (nonresponsive celiac disease) appears to be a manifestation of enteropathy-associated T-cell lymphoma in most cases.

Celiac disease: strongly heritable, oligogenic, but genetically complex

Celiac disease, or gluten-sensitive enteropathy, is a small intestinal disorder which affects up to 1:250 people in the United States. Disease development has a strong genetic component, with a sibling relative risk (lambda(s)) of 30. One susceptibility locus is the MHC region, with a particular association with the HLA-DQ alleles DQA1*0501 and DQB1*0201. However, haplotype sharing studies suggest that genes within the MHC complex contribute no more than 40% to the sibling familial risk of disease. This means that the stronger genetic risk is likely to be conferred by a small number of non-HLA-linked genes. Genome-wide linkage studies, plus linkage and association studies of candidate loci have been used to try to identify these genes. However, these studies have either failed to detect loci, or produced inconsistent results. Such difficulties in identifying susceptibility genes are encountered when investigating any complex genetic disorder. Information from the Human Genome Project, coupled with new technology for high throughput single nucleotide polymorphism typing may help to identify the non-HLA determinants of celiac disease in the future.

Genetics of celiac disease

Celiac disease (CD) is a chronic inflammatory disease of the gut resulting from ingestion of gluten, occurring in genetically susceptible individuals. The strong genetic association of CD with the DQ2 and DQ8 HLA heterodimers has been known for long, but others non-HLA genes are involved. In order to identify susceptibility genes to CD, several studies have been performed, based on either linkage analyses or candidate gene approaches. This review describes these different studies and their results. The hypothesis of the implication of the DR53 heterodimer in the HLA region has been proposed. The existence of a susceptibility locus on chromosome 5q has been evidenced through linkage analysis and candidate gene strategies have revealed the role of CTLA-4 and of the immunoglobulin gamma genes in the disease.