IgG(1) antiendomysium and IgG antitissue transglutaminase (anti-tTG) antibodies in coeliac patients with selective IgA deficiency. Working Groups on Celiac Disease of SIGEP and Club del Tenue

Guidelines for best practices in monitoring established coeliac disease in adult patients

Coeliac disease (CeD) is an immunological disease triggered by the consumption of gluten contained in food in individuals with a genetic predisposition. Diagnosis is based on the presence of small bowel mucosal atrophy and circulating autoantibodies (anti-type 2 transglutaminase antibodies). After diagnosis, patients follow a strict, life-long gluten-free diet. Although the criteria for diagnosis of this disease are well defined, the monitoring phase has been studied less and there is a lack of specific guidelines for this phase. To develop a set of clinical guidelines for CeD monitoring, we followed the Grading of Recommendations Assessment, Development and Evaluation methodology. Statements and recommendations with the level of evidence were developed and approved by the working group, which comprised gastroenterologists, pathologists, dieticians and biostatisticians. The proposed guidelines, endorsed by the North American and European coeliac disease scientific societies, make recommendations for best practices in monitoring patients with CeD based on the available evidence. The evidence level is low for many topics, suggesting that further research in specific aspects of CeD would be valuable. In conclusion, the present guidelines support clinicians in improving CeD treatment and follow-up and highlight novel issues that should be considered in future studies.

Study of the immune response in celiac patients with selective IgA deficiency who start a gluten-free diet

Studies are scarce regarding IgG anti-tissue transglutaminase 2 (tTG) normalization in selective IgA deficient (SIgAD) celiac disease (CD) patients after beginning a gluten free diet (GFD). The aim of this study is to analyse the decreasing dynamics of IgG anti-tTG in patients diagnosed with CD who start a GFD. To achieve this objective, IgG and IgA anti-tTG levels at diagnosis and during follow-up in 11 SIgAD CD patients and in 20 IgA competent CD patients were retrospectively evaluated. At diagnosis, statistical differences were not found when comparing IgA anti-tTG levels of IgA competent subjects with IgG anti-tTG levels of SIgAD subjects. Regarding the decreasing dynamics, even though no statistical differences were found (p = 0.06), normalization rates were slower for SIgAD CD patients. After 1 and 2 years on GFD, respectively, only 18.2% and 36.3% of the SIgAD CD patients normalized IgG anti-tTG levels; otherwise, IgA anti-tTG reached values under the reference values in 30% and 80% of the IgA competent patients in the same time-points. Although IgG anti-tTG has demonstrated a high diagnostic efficiency in SIgAD CD pediatric patients, this test does not appear to be as precise for long-term GFD response monitoring as IgA anti-tTG levels in IgA sufficient patients.

Humoral immune response to COVID-19 infection or vaccination among celiac disease patients

Introduction

Celiac disease (CD) is the most common autoimmune disease (AD) of the small intestine, affecting 1-2% of the population globally. It is characterized by the serological presence of autoantibodies (Abs), tissue transglutaminase antibody (tTGA), immunoglobulin (Ig) A, and IgG. Production of antibodies against SARS-CoV-2 after infection with the virus or vaccination is not well understood, especially among CD patients. The goal of this study was to measure the IgG antibodies in Jordanian patients infected with or vaccinated against the SARS-CoV-2 virus with different types of vaccines (Pfizer- BioNTech BNT162b2, Sinopharm BBIBP-CorV or Oxford-AstraZeneca ChAdOx1-S) and compare them with the levels in non-celiac controls. IgG levels induced by different vaccines were also compared.

Material and methods

The data for this cross-sectional study were obtained via a survey, whereby respondents were identified through convenience sampling. The healthy controls were given Questionnaire A while CD patients completed Questionnaire B. The blood samples from all participants were tested for the COVID-19 nucleocapsid protein (NP) IgG serum levels for participants previously infected with SARS-CoV-2, and spike (S) protein (S1/S2) IgG serum levels for vaccine recipients.

Results

The study involved 116 individuals, 60 (51.7%) of whom were CD patients. The NP IgG serum levels in the infected and S1/S2 IgG levels in the vaccinated CD patients were significantly lower than the levels in controls (48.3 ±44.5 vs. 81.1 ±34.4 and 49 ±45.8 vs. 75.7 ±38.6, p = 0.002). Moreover, only the Pfizer vaccine induced significantly more IgG antibodies in controls compared to CD patients (88.8 ±29.1 vs. 58.3 ±45.4, p = 0.01). On the other hand, the IgG levels were significantly higher in CD patients who received the Pfizer relative to the AstraZeneca vaccine (58.3 ±45.5 vs. 13.0 ±23.6, p = 0.03). After adjusting for presence of CD, age, sex, body mass index (BMI), comorbidities, vaccine type, smoking, gluten adherence, and time since infection or vaccination, SARS-CoV-2 S1/S2 IgG Abs and/or NP IgG Abs positivity was significantly associated with CD absence and negatively with vaccine type (AstraZeneca) with the odds ratios (ORs) of 9.6 (95% CI = 1.5-59.2, p = 0.015) and 0.03 (95% CI = 0.004-0.244. p = 0.001), respectively.

Conclusions

We concluded that patients with CD had lower SARS-CoV-2 S1/S2 IgG Abs and NP IgG Abs levels than controls, and CD patients who received the Pfizer vaccine had higher IgG levels than patients who received the AstraZeneca vaccine. We recommend that further research be conducted to address the dynamics of the antibody responses in CD patients regarding COVID-19 infection.

Clinical classification and long-term outcomes of seronegative coeliac disease: a 20-year multicentre follow-up study

BACKGROUND

Seronegative coeliac disease is poorly defined.

AIMS

To study clinical phenotypes and long-term outcomes of seronegative coeliac disease in a multicentre cohort over 20 years.

METHODS

Seronegative coeliac disease was diagnosed in HLA-DQ2/DQ8-positive patients with villous atrophy (VA), negative IgA endomysial (EmA), tissue transglutaminase (tTG) and deamidated-gliadin antibodies (DGP), clinical and histological response to a gluten-free diet (GFD), and no alternative causes for VA. In patients with IgA deficiency, coeliac disease was diagnosed through VA, positive IgG EmA/tTG/DGP and clinical/histological response to a GFD (coeliac disease+IgAd). Patients with seropositive coeliac disease served as controls.

RESULTS

Of 227 patients previously diagnosed with seronegative coeliac disease, true seronegative coeliac disease was confirmed in 84, coeliac disease+IgAd in 48, and excluded in 55. Lack of follow-up duodenal biopsy precluded diagnosing seronegative coeliac disease in 40 patients. 2084 patients with seropositive coeliac disease served as controls. True seronegative coeliac disease had more severe symptoms at diagnosis and a higher risk of complications (HR 10.87, 95% CI 6.11-19.33, P < 0.001) and mortality (HR 2.18, 95% CI 1.12-4.26, P < 0.01) than seropositive coeliac disease. There were no differences between true seronegative coeliac disease and coeliac disease+IgAd. On multivariate analysis, age at diagnosis, lack of clinical response to a GFD, true seronegative coeliac disease, coeliac disease+IgAd, and classical presentation predicted complications. Age at diagnosis, complications and absence of clinical response to a GFD predicted mortality.

CONCLUSIONS

Seronegative coeliac disease has a more aggressive disease phenotype than seropositive coeliac disease. These data argue against over-reliance on serology for the diagnosis of coeliac disease and support a strict clinical and histologic follow-up in seronegative coeliac disease.

Diagnosing and Monitoring Celiac Patients with Selective IgA Deficiency: Still an Open Issue

Although, the association between celiac disease (CD) and selective immunoglobulin A deficiency (SIgAD) has been known for more than fifty years, the procedures for diagnosing and monitoring patients with both conditions are still far from definitive. When serological markers were introduced as pre-bioptic investigations, it was immediately clear that searching for specific IgA antibodies without checking total serum IgA could lead to a failure in diagnosing IgA-deficient CD patients, while specific IgG antibodies could be useful as additional tests, because they are frequently found in the serum of affected patients. Nonetheless, until recently the diagnosis of CD in IgA-deficient patients was based on the few, fragmentary and often contradictory data available in literature. The introduction of the European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) guidelines in 2012 provided the current criteria for diagnosing CD in IgA-deficient patients, although some issues remained open, such as the selection of patients who should undergo specific IgG antibody testing and the choice of the most reliable IgG-based test for both diagnosis and follow-up. A real-life study recently assessed the impact of the 2012 ESPGHAN guidelines in diagnosing and monitoring CD in SIgAD patients, highlighting several pitfalls that can lead to operational uncertainties and difficulties in patient management. In the present report, the evolution of diagnostic tools and criteria for CD in SIgAD patients has been critically assessed, both strengths and open issues have been highlighted, and future perspectives for improving the current diagnostic protocols have been suggested.

Influence of the 2012 European Guidelines in Diagnosis and Follow-up of Coeliac Children With Selective IgA Deficiency

OBJECTIVES

The aim of the study was to describe diagnostic criteria used in children with coeliac disease (CD) and selective IgA deficiency; to determine if the publication of the 2012 ESPGHAN criteria prompted any changes; to evaluate the evolution of serological markers.

METHODS

Multicenter, retrospective, descriptive study of a cohort of children under 15 years with selective IgA deficiency diagnosed with CD (January 2006 to December 2016). Demographic, clinical, genetic, histological and IgG-based antibodies were collected at diagnosis and follow-up.

RESULTS

Eighty-six children were included, 60 diagnosed after the guide. Two groups were established: G1 (n = 63) and G2 (n = 23) with or without diagnostic biopsy respectively. In G1: 87.3% were symptomatic, 87.3% had human leukocyte antigan (HLA) DQ2/DQ8 typing (all positive), all had IgG serology positive (71.5% ATG, 35% EMA, 19% DPG, 9.5% AGA), and all had villous atrophy (Marsh-Oberhuber 2-3). Follow-up data were available in 58 children, 34 after 2 years on a gluten-free diet. Fifty-two percentage remained ATG IgG-positive despite good dietary adherence and symptom remission. Regarding G2: all were diagnosed post-2012, had typical symptoms, HLA DQ2/DQ8 positive and ATG IgG × 10 ULN. Additionally, EMA IgG was performed in 14 (60%), all positive.

CONCLUSIONS

In our cohort of children with selective IgA deficiency and diagnosed with CD, children without a diagnostic biopsy suggests that IgG serology was considered the equivalent as IgA isotype, even when this is not addressed in the aforementioned guidelines. Great heterogeneity was observed in the IgG serology used at diagnosis. After 2 years of a gluten-free diet, half of children remained with a positive serology.

Pitfalls in the Diagnosis of Coeliac Disease and Gluten-Related Disorders

The spectrum of gluten-related disorders (GRD) has emerged as a relevant phenomenon possibly impacting on health care procedures and costs worldwide. Current classification of GRD is mainly based on their pathophysiology, and the following categories can be distinguished: immune-mediated disorders that include coeliac disease (CD), dermatitis herpetiformis (DH), and gluten ataxia (GA); allergic reactions such as wheat allergy (WA); and non-coeliac gluten sensitivity (NCGS), a condition characterized by both gastrointestinal and extra-intestinal symptoms subjectively believed to be induced by the ingestion of gluten/wheat that has recently gained popularity. Although CD, DH, and WA are well-defined clinical entities, whose diagnosis is based on specific diagnostic criteria, a diagnosis of NCGS may on the contrary be considered only after the exclusion of other organic disorders. Neither allergic nor autoimmune mechanisms have been found to be involved in NCGS. Mistakes in the diagnosis of GRD are still a relevant clinical problem that may result in overtreatment of patients being unnecessary started on a gluten-free diet and waste of health-care resources. On the basis of our clinical experience and literature, we aim to identify the main pitfalls in the diagnosis of CD and its complications, DH, and WA. We provide a practical methodological approach to guide clinicians on how to recognize and avoid them.

Role of anti-tissue transglutaminase IgA+IgG antibodies in detection of potential celiac disease in patients with type 1 diabetes

Background & objectives:

Celiac disease (CD) can exist in various forms in type 1 diabetes (T1D) patients and can remain undetected, leading to severe complications. This study was aimed to evaluate five commercially available anti-tissue transglutaminase (tTG) ELISA kits with distinct formats for the detection of CD and potential CD in T1D patients. Clinical and demographic profiles of the patients with different disease subsets were also studied.

Methods:

Fifty T1D patients with classical and non-classical symptoms of CD and 100 T1D patients without any symptoms of CD were included in this study. Anti-tTG autoantibody levels were estimated by five ELISA kits followed by histological examination of duodenal biopsy. HLA DQ2-DQ8 and DRB1-DQB1 typing was done, and serum levels for transforming growth factor (TGF)-β1 were also estimated.

Results:

Assay format detecting anti-tTG IgA antibodies against recombinant antigens along with neopeptides of gliadin was most efficient in the detection of CD in symptomatic patients, and assay format detecting IgA+IgG helped in the detection of potential CD in asymptomatic T1D patients. These findings were supported by histological examination and human leucocyte antigen analysis. Patients with potential CD were found to have markedly deranged glycaemic control parameters and also had significantly raised serum levels of TGF-β1, (P<0.05) compared to T1D patients.

Interpretation & conclusions:

Potential CD can be frequently seen in T1D patients. This can be attributed to the dietary patterns prevalent in the subcontinent and the genetic basis of the disease. Anti-tTG IgA+IgG antibodies can be useful in the detection of these potential CD cases in T1D patients. Early intervention with gluten-free diet can be considered in these patients for better disease management.

Clinical and biological correlations in celiac disease in children: the prospective single experience of a romanian tertiary center: A case-control study (Strobe-Compliant study)

Celiac disease-a chronic inflammatory disease of the intestine-is triggered by gluten or associated protein consumption.The aim of our study was to assess the sensitivity, specificity of the combined anti-transglutaminase 2 (TG2)/deamidated gliadin peptide antibodies (DGP), and antiendomisium antibodies (EMA), to determine the distribution of HLA-DQ2/DQ8 for the 140 tested patients, and also to evaluate the clinical and laboratory characteristics of patients admitted with the suspicion of celiac disease (CD). Children included in the study were divided into: group 1, patients with confirmed CD; group 2, patients with "potential' CD; group 3, control group, patients without CD. We assessed the standard laboratory data, the level of TG2/DGP and EMA antibodies, as well as the distribution of HLA molecules in the selected patients. Histopathological examination was considered the criterion standard for diagnosis in most cases.The sensitivity of TG2/DGP was 85% and the specificity 92%. EMA showed a sensitivity of 82% and a specificity of 98%. The vast majority of patients diagnosed with CD were either HLA-DQ2.5 (encoded by DQA1*05 & DQB1*02) positive (87.5%) or HLA-DQ8 (encoded by DQB1*03:02) positive (12.5%). One patient showed a positivity only for HLA-DQ2.2 (encoded by DQA1*02 & B1*02).Our study showed that the genetic risk for CD was present in more than one-third of the cases without a confirmed diagnosis of CD. Therefore, the awareness of genetic susceptibility for CD is essential because of the fact that these individuals can develop the disease at any point of their lives. The sensitivity of TG2/DGP and EMA were very similar, whereas EMA presented a higher specificity as that of TG2/DGP.

Lack of Utility of Anti-tTG IgG to Diagnose Celiac Disease When Anti-tTG IgA Is Negative

OBJECTIVES

Guidelines for diagnosing celiac disease (CD) recommend initial testing with a highly sensitive serologic test for anti-tissue transglutaminase immunoglobulin A antibodies (tTG IgA). When the probability of CD is high, IgA deficiency should be considered. The 2 approaches to address this include measuring "both tTG IgA and tTG IgG" or measuring "total IgA." We aim to assess the utility of an isolated positive tTG IgG result in diagnosing CD.

METHODS

We conducted a retrospective review of patients undergoing serologic testing for CD from January 1997 to June 2014. Patients with positive tTG IgG and negative tTG IgA were included. Moreover, all patients who had any other positive CD-specific serologic findings were excluded. Demographics, clinical presentation, tests, and biopsy results were recorded.

RESULTS

The indication for checking celiac serology was gastrointestinal symptoms in 172 of 233 patients, iron deficiency anemia in 12, and high-risk screening in 48. Small bowel biopsy was performed in 178 patients (77%); 160 had normal results and 18 had histologic changes suggestive of enteropathy. Nine patients had increased intraepithelial lymphocytes, and 9 had partial villous atrophy. Only 6 cases of CD were, however, confirmed. The utility of isolated tTG IgG in diagnosis of CD was low at 3% (6/178).

CONCLUSION

In this cohort of patients, the utility of isolated tTG IgG in diagnosing CD was low at 3%.

Overview of biomarkers for diagnosis and monitoring of celiac disease

Among the adverse reactions caused by wheat, celiac disease (CD) is the longest studied and best-known pathology. The more recently defined non-celiac gluten sensitivity (NCGS) presents with symptoms which are often indistinguishable from CD. Diagnosis of CD is based on serologic, molecular, and bioptic testing. The IgA anti-transglutaminase (tTG) test is considered highly important, as it shows high sensitivity and specificity and its levels correlate to the degree of intestinal damage. Small bowel biopsy can be avoided in symptomatic patients with IgA anti-tTG levels above 10× the manufacturer's cut-off. Recently, tests of anti-deamidated peptides of gliadin (DGP) have replaced classic anti-native gliadin (AGA) tests. DGP assays have a considerably higher diagnostic accuracy than AGA assays, especially in the IgG class, and can replace anti-tTG tests in patients with selective IgA deficiency. The combination of IgG anti-DGP plus IgA anti-tTG assays show greater sensitivity than a single test, with very high specificity. EMA tests have great diagnostic accuracy but are not recommended by all the latest guidelines because they are observer dependent. Biopsy must still be considered the gold standard for CD diagnosis. HLA-DQ genotyping can be used to screen asymptomatic children and in cases of histology/serology disagreement. About half of NCGS patients are DQ2 positive and have IgG AGA. To diagnose NCGS, first CD and wheat allergy must be excluded; then the wheat dependence of symptoms must be verified by a gluten-free diet and subsequent gluten challenge.

Serum markers in the clinical management of celiac disease

The advent of highly reliable noninvasive celiac diagnostic tests has transformed the field of celiac disease, from diagnosis, to evaluation of epidemiology, to clinical and translational research. Serologic tests in their modern forms are highly sensitive and specific for diagnosis, allowing for consideration of avoidance of diagnostic intestinal biopsy in some settings. On the other hand, as predictors of intestinal damage and for use in monitoring disease activity, currently available noninvasive tests have been disappointing. Serologic tests, while a measure of disease activity, do not correlate well with histology or symptomatology, and it is unclear if they predict long-term risk. Additionally, while the many clinically available tests have improved accessibility, they can have widely different cutoff levels and overall performance, making the comparison of levels in individual patients over time and across populations quite difficult. In the future, we can expect to see improvement in the currently available serologic tests including tissue transglutaminase and deamidated gliadin peptide with expansion of the dynamic range of the tests, and the celiac care community should push for a standardization of assays that would simplify research and patient care. Additionally, current serologic tests are measures of the adaptive immune response in celiac disease but do not directly measure intestinal inflammation. Promising work on intestinal fatty acid-binding protein and other assays which directly measure intestinal damage may complement traditional serologic tests and further improve our ability to noninvasively diagnose and monitor celiac disease. The coming years hold promise for the continuing evolution of serum-based tests in celiac disease with the possibility of substantial improvement of patient care and clinical research.

Celiac Disease: Diagnosis

Historically the diagnosis of celiac disease has relied upon clinical, serological, and histological evidence. In recent years the use of sensitive serological methods has meant an increase in the diagnosis of celiac disease. The heterogeneous nature of the disorder presents a challenge in the study and diagnosis of the disease with patients varying from subclinical or latent disease to patients with overt symptoms. Furthermore the related gluten-sensitive disease dermatitis herpetiformis, while distinct in some respects, shares clinical and serological features with celiac disease. Here we summarize current best practice for the diagnosis of celiac disease and briefly discuss newer approaches. The advent of next-generation assays for diagnosis and newer clinical protocols may result in more sensitive screening and ultimately the possible replacement of the intestinal biopsy as the gold standard for celiac disease diagnosis.

Utility of testing patients, on presentation, for serologic features of celiac disease

BACKGROUND & AIMS

Celiac disease shares features of other disorders. It can be diagnosed conclusively only based on duodenal histology analysis, which is not practical for screening purposes. Serologic analysis might be used to identify candidates for biopsy analysis. We aimed to develop a simple diagnostic approach that all clinicians could follow to increase the percentage of patients accurately diagnosed with celiac disease at initial presentation.

METHODS

We performed a retrospective analysis of data from 752 patients (88 with celiac disease, none were IgA deficient) who attended a UK district general hospital from January 2007 through December 2008 and underwent biopsy analysis and serologic tests to measure endomyseal antibodies and IgA antibodies against tissue transglutaminase (tTG). Patients avoiding gluten in their diet were excluded. Patients were assigned to 1 of 4 groups: high-risk (based on presence of anemia, chronic diarrhea, unintentional weight loss, or dermatitis herpetiformis), low-risk (based on such factors as dyspepsia, abnormal liver function, ataxia, or chronic cough), nutrient deficiency (based on levels of iron, vitamins B12 and D, or folate), or screening (because they had type 1 diabetes or a family history of celiac disease). Patients with celiac disease were identified using the modified Marsh criteria (grades 1-3) for interpreting duodenal histology. We compared clinical category, serology profiles, and biopsy results between patients with and without celiac disease.

RESULTS

Celiac disease was diagnosed in 64 of 565 patients in the high-risk group (11%), 14 of 156 patients in the low-risk group (9%; P = .47 compared with high-risk group), 7 of 28 patients in the nutrient-deficiency group, and 3 of 3 patients in the screening group. Among 71 patients who tested positive for both antibodies (tTG and endomyseal antibodies), the positive predictive value for celiac disease was 97%; a negative test result for tTG had a negative predictive value of 98%. Among 708 patients with normal-looking biopsy samples, only 62 had celiac disease (9%). Among 44 patients with abnormal biopsy samples, 26 had celiac disease (59%).

CONCLUSIONS

Based on a retrospective analysis, patients with and without celiac disease cannot be distinguished based on clinical features. Patients who present with symptoms of celiac disease should be tested for tTG, to identify candidates for duodenal biopsy analysis.

Serological assessment for celiac disease in IgA deficient adults

PURPOSE

Selective immunoglobulin A deficiency is the most common primary immunodeficiency disorder that is strongly overrepresented among patients with celiac disease (CD). IgG antibodies against tissue transglutaminase (tTG) and deamidated gliadin peptides (DGP) serve as serological markers for CD in IgA deficient individuals, although the diagnostic value remains uncertain. The aim of this study was to investigate the prevalence of these markers in a large cohort of IgA deficient adults with confirmed or suspected CD and relate the findings to gluten free diet.

METHODS

Sera from 488,156 individuals were screened for CD in seven Swedish clinical immunology laboratories between 1998 and 2012. In total, 356 out of 1,414 identified IgA deficient adults agreed to participate in this study and were resampled. Forty-seven IgA deficient blood donors served as controls. Analyses of IgG antibodies against tTG and DGP as well as HLA typing were performed and a questionnaire was used to investigate adherence to gluten free diet. Available biopsy results were collected.

RESULTS

Out of the 356 IgA deficient resampled adults, 67 (18.8%) were positive for IgG anti-tTG and 79 (22.2%) for IgG anti-DGP, 54 had biopsy confirmed CD. Among the 47 IgA deficient blood donors, 4 (9%) were positive for IgG anti-tTG and 8 (17%) for anti-DGP. Four were diagnosed with biopsy verified CD, however, 2 of the patients were negative for all markers. Sixty-eight of 69 individuals with positive IgG anti-tTG were HLA-DQ2/DQ8 positive whereas 7 (18.9%) of the 37 individuals positive for IgG anti-DGP alone were not.

CONCLUSIONS

IgG anti-tTG seems to be a more reliable marker for CD in IgA deficient adults whereas the diagnostic specificity of anti-DGP appears to be lower. High levels of IgG antibodies against tTG and DGP were frequently found in IgA deficient adults despite adhering to gluten free diet.

Immunoglobulin A deficiency in celiac disease

GOALS

To determine the prevalence and significance of immunoglobulin A (IgA) deficiency and partial deficiency in patients with celiac disease (CD).

BACKGROUND

Selective IgA deficiency is a common primary immunoglobulin deficiency and has a higher prevalence in patients with CD. The prevalence and significance of IgA deficiency and partial deficiency in patients with CD in the United States has not previously been examined.

STUDY

A retrospective, cohort study of 1498 adults and 317 children seen in a University Medical Center was conducted.

RESULTS

There were 26 patients (22 adults, 4 children) with CD who were IgA deficient and 11 (9 adults, 2 children) with CD who were partially IgA deficient. The prevalence of IgA deficiency/partial deficiency was similar among adults and children (2.1% and 1.9%, respectively, P=0.99). Among adults, concomitant autoimmune disease was present in 29% of IgA-deficient/partially deficient patients versus 12% of CD patients with normal IgA levels (P=0.0081). All 4 IgA-deficient patients who had persistently positive IgG celiac serologies while adherent to a gluten-free diet and were rebiopsied had a normal repeat biopsy. Both positive tissue transglutaminase IgG and antigliadin IgG were found in these patients.

CONCLUSIONS

Selective IgA deficiency/partial deficiency is present in 2% of CD patients at this referral center and is equally prevalent among adults and children. IgA-deficient/partially deficient adults had a higher prevalence of concomitant autoimmune disease than those without IgA deficiency. In patients who are IgA deficient, IgG serologies may be persistently elevated despite histologic recovery.

The significance of duodenal mucosal atrophy in patients with common variable immunodeficiency: a clinical and histopathologic study

Gastrointestinal manifestations and villous atrophy can be seen in patients with common variable immunodeficiency (CVID). In some patients, infectious agents may be responsible, whereas in others, celiac disease (CD) may be the cause. In this study, we investigate the causes and the histopathologic features seen in patients with CVID. Eleven patients with CVID and villous atrophy underwent duodenal biopsies, human leukocyte antigen (HLA) typing, and testing for all celiac antibodies. Fifteen patients with CVID and normal villi and 6 patients with CD but without CVID served as controls. Histologic response to a gluten-free diet (GFD) allowed a diagnosis of CD in 3 of 11 patients. In the remaining 8, the lack of a histologic response to a GFD or HLA typing excluded CD. Celiac antibodies gave conflicting results and were of no help. Polymorphonuclear infiltrates and lesions like graft-versus-host disease are seen more often in flat mucosa unresponsive to a GFD. However, the specificity of these findings remains to be determined and response to a GFD remains the only diagnostic criteria for CD in these patients. Villous atrophy was gluten-sensitive in 3 of 11 patients with CVID. It was not related to gluten-responsive CD in most patients.

Accuracy of diagnostic antibody tests for coeliac disease in children: summary of an evidence report

OBJECTIVE

The aim of this study was to summarise the evidence from 2004 to September 2009 on the performance of laboratory-based serological and point of care (POC) tests for diagnosing coeliac disease (CD) in children using histology as reference standard.

PATIENTS AND METHODS

We searched MEDLINE and EMBASE for studies reporting on children for tests based on IgA and IgG anti-gliadin (AGA), endomysial (EmA), anti-transglutaminase-2 (TG2), and anti-deamidated gliadin peptides (DGP) antibodies or POC tests. For inclusion, histological analysis of duodenal biopsies and sensitivity and specificity for index tests had to be reported. Data were pooled and summary measures calculated for sensitivity, specificity, positive and negative likelihood ratios ("LR+", "LR-"), and diagnostic odds ratios (DOR). In case of elevated statistical heterogeneity, studies reaching 90% sensitivity or specificity were reported.

RESULTS

A total of 2510 articles were reviewed; 16 entered meta-analysis, reporting on 3110 patients (1876 with CD, 1234 without CD). For IgA-EmA, sensitivity was ≥90% in 7/11 studies and pooled specificity 98.2%. For IgA-anti-TG2, 11/15 studies yielded sensitivities ≥90% and 13/15 specificities ≥90%. For IgA-DGP, sensitivity ranged between 80.7% and 95.1% (specificity 86.3%-93.1%); for IgG-DGP between 80.1% and 98.6% (specificity 86.0-96.9%). IgA-EmA had the highest pooled DOR (554) and LR+ (31.8) for a laboratory test, followed by IgA-anti-TG2, IgG-DGP, IgA-DGP and IgA-AGA. POC tests showed a pooled sensitivity of 96.4% for IgA-TG2 (specificity 97.7%).

CONCLUSIONS

IgA-EmA and IgA-anti-TG2 tests appear highly accurate to diagnose CD. IgG-anti-DGP tests may help in excluding CD. IgA-AGA and IgA-DGP tests show inferior accuracy. POC tests may achieve high accuracy in the hands of experienced readers, but IgA-anti-TG2/EmA were superior.

European Society for Pediatric Gastroenterology, Hepatology, and Nutrition guidelines for the diagnosis of coeliac disease

OBJECTIVE

Diagnostic criteria for coeliac disease (CD) from the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) were published in 1990. Since then, the autoantigen in CD, tissue transglutaminase, has been identified; the perception of CD has changed from that of a rather uncommon enteropathy to a common multiorgan disease strongly dependent on the haplotypes human leukocyte antigen (HLA)-DQ2 and HLA-DQ8; and CD-specific antibody tests have improved.

METHODS

A panel of 17 experts defined CD and developed new diagnostic criteria based on the Delphi process. Two groups of patients were defined with different diagnostic approaches to diagnose CD: children with symptoms suggestive of CD (group 1) and asymptomatic children at increased risk for CD (group 2). The 2004 National Institutes of Health/Agency for Healthcare Research and Quality report and a systematic literature search on antibody tests for CD in paediatric patients covering the years 2004 to 2009 was the basis for the evidence-based recommendations on CD-specific antibody testing.

RESULTS

In group 1, the diagnosis of CD is based on symptoms, positive serology, and histology that is consistent with CD. If immunoglobulin A anti-tissue transglutaminase type 2 antibody titers are high (>10 times the upper limit of normal), then the option is to diagnose CD without duodenal biopsies by applying a strict protocol with further laboratory tests. In group 2, the diagnosis of CD is based on positive serology and histology. HLA-DQ2 and HLA-DQ8 testing is valuable because CD is unlikely if both haplotypes are negative.

CONCLUSIONS

The aim of the new guidelines was to achieve a high diagnostic accuracy and to reduce the burden for patients and their families. The performance of these guidelines in clinical practice should be evaluated prospectively.

What is the use of biopsy and antibodies in coeliac disease diagnosis?

The advent of highly sensitive and specific serological markers has led to some protagonists proposing that coeliac disease can be diagnosed without the need for a biopsy. However, this is an area of controversy. Lack of consensus about diagnostic degrees of histological change, paucity of symptoms, antibody-negative disease and immunodeficiency can make diagnosis difficult even with a biopsy. Conversely, an argument can be put forward for a 'no biopsy' approach based on the large number of patients with typical symptoms and positive serology who experience a diagnostic delay. In addition, endoscopy is not without discomfort. This article discusses the use of antibodies and duodenal biopsy within this context. Finally, we propose a pragmatic diagnostic algorithm for clinicians to use when investigating patients for coeliac disease.

Clinical and metabolic effects of gluten free diet in children with type 1 diabetes and coeliac disease

BACKGROUND

Following the recommendations of The International Society for Pediatric and Adolescent Diabetes (ISPAD) in 2000, our clinic started routine screening of children with type 1 diabetes (T1D) for coeliac disease (CD).

OBJECTIVES

To determine the short-term clinical and metabolic effects of gluten free diet (GFD) in a group of children with T1D and confirmed CD.

METHODS

Data were collected on all children with T1D and CD between November 2000 and November 2007 before and 12 months after commencement of GFD. Data included the presence of gastrointestinal (GI) symptoms, episodes of severe hypoglycaemia, daily insulin requirements, height, weight, body mass index (BMI), glycosylated haemoglobin (HbA1c), haemoglobin, and persistence of autoantibodies. The effects of GFD on these parameters were studied and compared with those from the revised ISPAD Guidelines in 2007.

RESULTS

Four hundred and sixty-eight children with T1D were screened, of whom 23 patients were diagnosed with CD. The mean age at diagnosis of T1D and CD was 6.8 years and 11.1 years, respectively. Ten out of 11 children showed improvement in their GI symptoms, while 6 out of 8 patients had no further severe hypoglycaemic episodes. Nine patients remained positive for antiendomysial antibodies after GFD. There was no significant change in the standard deviation score for height, weight, and BMI or the mean HbA1c and Hb before and after GFD. However the mean insulin requirement increased from 0.88 to 1.1 units/kg/day, which was statistically significant (p < 0.005).

CONCLUSION

In our experience, GFD showed short-term benefits by reducing GI symptoms and severe hypoglycaemia while the insulin requirement increased significantly.

Novel trends in celiac disease

Celiac disease (CD) is one of the most common food intolerances in developed world. It affects genetically susceptible individuals and has severe consequences if it remains undiagnosed. A disease known for more than a century, it is still the focus for experts from various fields of research and development. Geneticists, pathologists, immunologists, food engineers and dieticians share their knowledge and expertise to improve the conditions of CD patients. With new insights in the pathomechanism of gluten processing and antigen presentation in CD, it was possible to improve the diagnostic antigen mimicking the primary epitope in CD. These celiac neo-epitopes are comprised of a complex of gliadin peptides crosslinked with transglutaminase (tTg). They are an early diagnostic marker for CD which occurs up to 6 months earlier than classical markers known to miss a certain amount of CD patients.

Update on serologic testing in celiac disease

Contemporary serologic testing has revolutionized the field of celiac disease (CD). Highly accurate serologic assays have shown the prevalence of CD to be nearly 1:100 in many populations. These mostly ELISA (enzyme-linked immunosorbent assay)-based tests allow noninvasive screening and detection. However, the growing number of available serologic tests necessitates reevaluation of their predictive power as a single test or in combination. We review the available tests for CD, including antibodies against gliadin, endomysium, tissue transglutaminase, and deamidated gliadin, and the evidence for preferential use of specific tests in different settings. Despite several novel developments, standardized ELISA-based assays for IgA autoantibodies against tissue transglutaminase remain the test of choice for most populations. We discuss the need to develop tests for CD activity in order to assess the efficacy of upcoming nondietary therapies.

The spectrum of celiac disease: epidemiology, clinical aspects and treatment

Celiac disease is a gluten-sensitive enteropathy that affects people of all ages worldwide. This disease has emerged as a major health-care problem, as advances in diagnostic and screening methods have revealed its global prevalence. Environmental factors such as gluten introduction at childhood, infectious agents and socioeconomic features, as well as the presence of HLA-DQ2 and/or HLA-DQ8 haplotypes or genetic variations in several non-HLA genes contribute to the development of celiac disease. Growing insight into the variable clinical and histopathological presentation features of this disease has opened new perspectives for future research. A strict life-long gluten-free diet is the only safe and efficient available treatment, yet it results in a social burden. Alternative treatment modalities focus on modification of dietary components, enzymatic degradation of gluten, inhibition of intestinal permeability and modulation of the immune response. A small group of patients with celiac disease (2-5%), however, fail to improve clinically and histologically upon elimination of dietary gluten. This complication is referred to as refractory celiac disease, and imposes a serious risk of developing a virtually lethal enteropathy-associated T-cell lymphoma.

Suboptimal performance of IgG anti-tissue transglutaminase in the diagnosis of celiac disease in a tropical country

Serological tests using human IgA-anti-tTG have been reported to have high sensitivity and specificity in diagnosis of celiac disease. There is a paucity of data on the use of human IgG-anti-tTG in diagnosis of celiac disease. Ninety-two patients with clinical suspicion of celiac disease who underwent duodenal mucosal biopsy and celiac serology using human IgG-anti-tTG were included in this retrospective study. Diagnostic accuracy of human recombinant IgG-anti-tTG serological test for celiac disease was evaluated. Indications for celiac serological testing were diarrhea (92.3%), hypoalbuminemia (39.1%), and anemia (35.9%). Eighteen patients were diagnosed with having celiac disease and 14 (77.8%) of them were IgG-anti-tTG positive. Of the remaining 74 patients, eight (10.8%) were false-positive for IgG-anti-tTG. Sensitivity, specificity, PPV, NPV, and diagnostic accuracy of IgG-anti-tTG in celiac disease were 77.8, 89.1, 63.6, 94.2, and 87%, respectively. Human IgG-anti-tTG alone does not perform well as a diagnostic tool for celiac disease. The utility of anti-endomysial antibodies in a similar clinical setting needs to be evaluated.

Diagnostic efficacy of the ELISA test for the detection of deamidated anti-gliadin peptide antibodies in the diagnosis and monitoring of celiac disease

BACKGROUND AND AIM

We evaluated the diagnostic performance of an ELISA test for anti-gliadin IgA and IgG antibodies, which uses synthetic deamidated gliadin peptides (anti-gliadin antibodies, AGAs) as coating; the results were compared with a test that uses extracted gliadin (AGAe).

METHODS

The study was conducted on the sera of 144 patients suffering from celiac disease (CD), including 20 patients with IgA deficiency and 9 who were following a gluten-free diet (GFD), and 129 controls.

RESULTS

In the 115 CD patients (without IgA deficiency), the sensitivity of AGAe IgA and IgG was 32.2 and 60.9%, whereas that of AGAs IgA and IgG was 59.1 and 72.2%. The specificity for AGAe IgA and IgG, and AGAs IgA and IgG was 93.8 and 89.9%, and 96.9% and 99.2%, respectively. Of the 20 patients with CD and IgA deficiency, 7 tested positive for AGAe IgG and 14 for AGAs IgG. The test using deamidated gliadin peptides performed better in terms of sensitivity and specificity than the AGA tests with extracted antigen.

CONCLUSIONS

The very high specificity of the AGAs IgG test (99.2%) also suggests that patients who test positive with this assay require a thorough followup, even if the anti-tissue transglutaminase antibodies (anti-tTG) and anti-endomysial autoantibodies (EMA) assays are negative.

Clinical presentation of celiac disease and the diagnostic accuracy of serologic markers in children

There has been growing recognition of a changing clinical presentation of celiac disease (CD), with the manifestation of milder symptoms. Serologic testing is widely used to screen patients with suspected CD and populations at risk. The aim of this retrospective analysis was to evaluate the clinical presentation of CD in childhood, assess the diagnostic value of serologic tests, and investigate the impact of IgA deficiency on diagnostic accuracy. We evaluated 206 consecutive children with suspected CD on the basis of clinical symptoms and positive serology results. Ninety-four (46%) had biopsy-proven CD. The median age at diagnosis of CD was 6.8 years; 15% of the children were <2 years of age. There was a higher incidence of CD in girls (p = 0.003). Iron deficiency and intestinal complaints were more frequent in children with CD than those without CD (61% vs. 33%, p = 0.0001 and 71% vs. 55%, p = 0.02, respectively), while failure to thrive was less common (35% vs. 53%, p = 0.02). The sensitivity of IgA tissue transglutaminase (IgA-tTG) was 0.98 when including all children and 1.00 after excluding children with selective IgA deficiency. The specificity of IgA-tTG was 0.73 using the recommended cut-off value of 20 IU, and this improved to 0.94 when using a higher cut-off value of 100 IU. All children with CD and relative IgA deficiency (IgA levels that are measurable but below the age reference [n = 8]) had elevated IgA-tTG. In conclusion, CD is frequently diagnosed in school-age children with relatively mild symptoms. The absence of intestinal symptoms does not preclude the diagnosis of CD; many children with CD do not report intestinal symptoms. While the sensitivity of IgA-tTG is excellent, its specificity is insufficient for the diagnostic confirmation of a disease requiring life-long dietary restrictions. Children with negative IgA-tTG and decreased but measurable IgA values are unlikely to have CD.

Coeliac disease

Coeliac disease is a chronic inflammatory disorder of the small bowel induced in genetically susceptible people by the irritant gluten and possibly other environmental cofactors. The disorder is characterised by a diverse clinical heterogeneity that ranges from asymptomatic to severely symptomatic, and it manifests with frank malabsorption, an increased morbidity attributable to the frequent association with autoimmune disorders and increased mortality resulting from the emergence of T-cell clonal proliferations that predispose the patient to enteropathy-type T-cell lymphoma. Our understanding of the molecular basis for this disorder has improved and enabled the identification of targets for new therapies, although a strict gluten-free diet remains the mainstay of safe and effective treatment. In this Seminar we critically reassess the clinical and diagnostic aspects of this disease and new perspectives in its pathogenesis and treatment.

Advances in celiac disease and gluten-free diet

Celiac disease is becoming an increasingly recognized autoimmune enteropathy caused by a permanent intolerance to gluten. Once thought to be a rare disease of childhood characterized by diarrhea, celiac disease is actually a multisystemic disorder that occurs as a result of an immune response to ingested gluten in genetically predisposed individuals. Screening studies have revealed that celiac disease is most common in asymptomatic adults in the United States. Although considerable scientific progress has been made in understanding celiac disease and in preventing or curing its manifestations, a strict gluten-free diet is the only treatment for celiac disease to date. Early diagnosis and treatment, together with regular follow-up visits with a dietitian, are necessary to ensure nutritional adequacy and to prevent malnutrition while adhering to the gluten-free diet for life. The purpose of this review is to provide clinicians with current updated information about celiac disease, its diverse clinical presentation and increased prevalence, the complex pathophysiology and strong genetic predisposition to celiac disease, and its diagnosis. This review focuses in detail on the gluten-free diet and the importance of intense expert dietary counseling for all patients with celiac disease. Recent advances in the gluten-free diet include food allergen labeling as well as the US Food and Drug Administration's proposed definition of the food-labeling term gluten-free. The gluten-free diet is complex and patients need comprehensive nutrition education from a skilled dietitian.

Celiac disease and IgA deficiency: complications of serological testing approaches encountered in the clinic

BACKGROUND

IgA deficiency causes false-negative IgA-based celiac serology results in patients with celiac disease. Using a case-finding strategy, we examined the prevalence of IgA deficiency, physician evaluation, and management of IgA deficiency during serological testing for celiac disease.

METHODS

We reviewed consecutive IgA-endomysial antibody (EMA) and serum IgA results from the laboratory database over 17 months. We cross-referenced seronegative patients with IgA deficiency (IgA <0.06 g/L) to the pathology database to evaluate intestinal biopsy results. Ordering physicians received a questionnaire regarding the management of seronegative patients with IgA deficiency who had no biopsy record.

RESULTS

Among the 9533 patients tested for IgA-EMA, 4698 (49%) were tested for IgA deficiency. IgA deficiency occurred in 35 of 4698 (0.75%) patients screened for IgA deficiency. Only 19 of 35 (54%) IgA-deficient patients were diagnosed appropriately with either intestinal biopsy (17 patients) or measurement of IgG-tissue transglutaminase (2 patients). Thirteen (76%) of the 17 IgA-deficient patients who underwent upper endoscopy with or without colonoscopy displayed gastrointestinal pathology on biopsies, including 3 (18%) with celiac disease. No further evaluation to exclude celiac disease was performed for the remaining 16 of 35 (46%) IgA-deficient, EMA-negative patients because of inappropriate management (6 patients), administrative error (7 patients), or patient/physician refusal (3 patients).

CONCLUSIONS

IgA deficiency occurred in 1:131 patients tested for celiac disease, and celiac disease occurred in 1:6 of those properly evaluated. Inadequate evaluation of IgA deficiency while testing for celiac disease occurred frequently and resulted in the underdiagnosis of both. Changes in testing algorithms and reporting of results were made to improve testing for celiac disease and IgA deficiency.

Cost-effectiveness analysis of strategies for diagnosing celiac disease

OBJECTIVE

To compare strategies for diagnosing celiac disease (CD).

METHODS

A decision analytic model was used to compare five strategies on diagnostic performance and costs.

RESULTS

First, tTG screening alone is the least costly strategy ($22/individual). While the NPV is high (99.8%), the PPV is low (63.4%). Second, if tTG-positive patients undergo esophagogastroduodenoscopy (EGD) to confirm CD, the PPV increases to 100% ($2,237/false-positive diagnosis avoided). Third, if EGDs are restricted to only those who are both tTG and HLA DQ2/8 positive, costs are slightly reduced ($59 vs. $63/individual), while PPV and NPV remain unchanged. Fourth, screening tTG-negative patients for IgA deficiency increases the NPV to 99.9% ($32,605/false-negative diagnosis avoided). Sensitivity analyses revealed that as the prevalence of CD increases, the cost of avoiding a false-positive diagnosis by adding EGD to the tTG alone strategy increases considerably.

CONCLUSIONS

When the pre-test probability of CD is low, patients with positive tTG serology should undergo EGD with biopsy-either directly or after positive screening for HLA DQ2/8-to confirm CD. As the pre-test probability of CD increases, the added cost of EGD should be weighed against the consequences of a false-positive diagnosis. Routinely screening for IgA deficiency in order to avoid a false-negative diagnosis is quite costly.

Celiac disease and autoimmune thyroid disease

Celiac disease (CD) or gluten sensitive enteropathy is relatively common in western populations with prevalence around 1%. With the recent availability of sensitive and specific serological testing, many patients who are either asymptomatic or have subtle symptoms can be shown to have CD. Patients with CD have modest increases in risks of malignancy and mortality compared to controls. The mortality among CD patients who comply poorly with a gluten-free diet is greater than in compliant patients. The pattern of presentation of CD has altered over the past three decades. Many cases are now detected in adulthood during investigation of problems as diverse as anemia, osteoporosis, autoimmune disorders, unexplained neurological syndromes, infertility and chronic hypertransaminasemia of uncertain cause. Among autoimmune disorders, increased prevalence of CD has been found in patients with autoimmune thyroid disease, type 1 diabetes mellitus, autoimmune liver diseases and inflammatory bowel disease. Prevalence of CD was noted to be 1% to 19% in patients with type 1 diabetes mellitus, 2% to 5% in autoimmune thyroid disorders and 3% to 7% in primary biliary cirrhosis in prospective studies. Conversely, there is also an increased prevalence of immune based disorders among patients with CD. The pathogenesis of co-existent autoimmune thyroid disease and CD is not known, but these conditions share similar HLA haplotypes and are associated with the gene encoding cytotoxic T-lymphocyte-associated antigen-4. Screening high risk patients for CD, such as those with autoimmune diseases, is a reasonable strategy given the increased prevalence. Treatment of CD with a gluten-free diet should reduce the recognized complications of this disease and provide benefits in both general health and perhaps life expectancy. It also improves glycemic control in patients with type 1 diabetes mellitus and enhances the absorption of medications for associated hypothyroidism and osteoporosis. It probably does not change the natural history of associated autoimmune disorders.

Detection of anti-endomysial and anti-tissue transglutaminase autoantibodies in media following culture of oral biopsies from patients with untreated coeliac disease

BACKGROUND AND AIMS

Coeliac disease is an autoimmune disorder characterised by high levels of anti-endomysial and anti-tissue transglutaminase autoantibodies in sera and media of cultured intestinal mucosa biopsies from affected patients. In this study, we wished to investigate whether anti-endomysial and anti-tissue transglutaminase antibodies can also be detected in culture media of oral mucosa specimens, and whether the mouth can be used as an area of immunological testing for coeliac disease.

METHODS

Small intestine and cheek biopsy samples taken from 16 patients with active coeliac disease and from 11 controls were cultured in vitro for 48 h at 37 degrees C in presence of medium alone. Anti-endomysial and anti-tissue transglutaminase were detected in sera and in supernatants of these cultured biopsy samples by indirect immunofluorescence and enzyme immunoassay (EIA), respectively.

RESULTS

Anti-endomysial and anti-tissue transglutaminase were positive in sera of 15/16 coeliac disease patients. Culture media of intestinal mucosa samples from 14/16 coeliac disease patients were anti-endomysial positive, while the same antibodies were positive in supernatants of cultured oral mucosa samples from 15/16 coeliac disease patients. Anti-tissue transglutaminase were positive in both intestinal and oral culture media of 15/16 coeliac disease patients. Neither anti-endomysial nor anti-tissue transglutaminase were found in sera or in culture supernatants of both intestinal and oral biopsy samples from 11 controls.

CONCLUSIONS

Our study suggests a new immunological site to detect the pathognomonic autoantibodies of coeliac disease and confirms that the mouth is involved in this illness.

Predictors of clinical response to gluten-free diet in patients diagnosed with diarrhea-predominant irritable bowel syndrome

BACKGROUND & AIMS

Gluten sensitivity might cause abdominal symptoms in the absence of villous atrophy. We examined the prevalence of celiac disease-associated serum antibodies in diarrhea-dominant irritable bowel syndrome (d-IBS) patients and their efficacy in combination with HLA-DQ2 expression to predict the response to gluten-free diet.

METHODS

HLA-DQA1*0501/DQB1*0201 expression and celiac disease-associated IgA and IgG serum antibodies against gliadin and tissue-transglutaminase were measured in 145 patients with d-IBS, 74 patients with untreated and treated celiac disease, and 57 patients with active IBD. Follow-up antibody levels, stool frequency, and gastrointestinal symptom scores were determined in 41 d-IBS patients (26 women, 15 men; median age, 46 years, range, 30-67 years) who participated in a nonrandomized evaluation of 6 months of gluten-free diet.

RESULTS

Increased celiac disease-associated serum IgG, but not IgA, was found in the majority of patients with treated (55%) as in most patients with untreated celiac disease (97%). In d-IBS patients, celiac disease-associated serum IgG antibodies (37%) and HLA-DQ2 expression (39%) were more frequent than in IBD patients (18% and 23%, respectively). After 6 months of gluten-free diet, stool frequency and gastrointestinal symptom score returned to normal values in 60% of d-IBS patients who were positive and in 12% who were negative for HLA-DQ2 and celiac disease-associated serum IgG; both parameters combined yielded positive and negative predictive values of 56% (95% confidence interval, 30%-80%) and 88% (69%-97%), respectively.

CONCLUSIONS

Celiac disease-associated serum IgG and HLA-DQ2 expression can identify likely responders to gluten-free diet in d-IBS patients.

Testing for IgG class antibodies in celiac disease patients with selective IgA deficiency. A comparison of the diagnostic accuracy of 9 IgG anti-tissue transglutaminase, 1 IgG anti-gliadin and 1 IgG anti-deaminated gliadin peptide antibody assays

BACKGROUND

To evaluate the diagnostic characteristics of commercially available IgG anti-tTG assays in selective IgA deficiency (SIgAD), we tested different IgG anti-tTG methods and compared the results with those obtained from two other tests: one for IgG anti-gliadin (AGA) and one for IgG to deaminated gliadin peptides (DGP).

METHODS

20 CD patients with SIgAD and 113 controls (9 patients with SIgAD without CD; 54 patients with chronic liver disease; 50 healthy subjects) were tested with 9 IgG anti-tTG assays (2 of which are enriched with gliadin peptides), one IgG AGA assay and one IgG anti-DGP assay.

RESULTS

Using optimal cutoffs as determined by ROC curves, the sensitivity of IgG anti-tTG methods ranged from 75% (1 kit) to 95% (7 kits) and the specificity from 94% (1 kit) to 100% (5 kits). Sensitivity and specificity were 40% and 87% for IgG AGA, and 80% and 98% for IgG anti-DGP, respectively.

CONCLUSIONS

All IgG anti-tTG methods evaluated are reliable serologic assays for the diagnosis of CD in patients with SIgAD and perform better than the gliadin-based assays used in this study. The tests containing both tTG and gliadinic peptides are burdened by a lower specificity than the anti-tTG assays.

Clinical value of immunoglobulin A antitransglutaminase assay in the diagnosis of celiac disease

OBJECTIVES

Our goal was to evaluate the possible correspondence between antitissue transglutaminase of immunoglobulin A class levels and stage of mucosal damage in patients affected by celiac disease. In addition, we assessed clinical use of antitissue transglutaminase values to predict biopsy results.

METHODS

One thousand eight hundred eighty-six consecutive patients with symptoms suggestive of celiac disease and 305 healthy controls underwent determination of serum levels of immunoglobulin A and antitissue transglutaminase. An intestinal biopsy was performed in subjects with antitissue transglutaminase levels > or = 4 IU/mL and in subjects with negative antitissue transglutaminase levels but with clinical suspicion of celiac disease. Histologic grading of celiac disease was consistent with the Marsh classification.

RESULTS

One hundred eighty-six subjects with positive antitissue transglutaminase levels and 91 patients with negative antitissue transglutaminase levels were submitted to biopsy. In all healthy subjects, antitissue transglutaminase results were negative. Histologic evaluations in patients with positive antitissue transglutaminase levels gave the following results: type 0 in 25 patients, type 1 in 3 patients, type 2 in 4 patients, type 3a in 22 patients, type 3b in 74 patients, and type 3c in 58 patients. None of the patients with negative antitissue transglutaminase levels showed histologic findings suggestive of celiac disease. The mean antitissue transglutaminase values in patients without mucosal atrophy were significantly lower than in patients with mucosal atrophy. Antitissue transglutaminase values > or = 20 IU/mL were found in only 1 patient without mucosal atrophy.

CONCLUSIONS

Our study found a strong correspondence between antitissue transglutaminase levels and stage of mucosal injury; antitissue transglutaminase values > 20 IU/mL seemed to be strongly predictive of mucosal atrophy.

Systematic review: the use of serology to exclude or diagnose coeliac disease (a comparison of the endomysial and tissue transglutaminase antibody tests)

BACKGROUND

With the appreciation of the high prevalence of coeliac disease there is increasing use of serology in screening asymptomatic people and testing those with suggestive features.

AIM

To compare the sensitivities and specificities of the endomysial antibody and the tissue transglutaminase antibody tests.

METHODS

Using electronic databases a search was made for relevant papers using the terms tissue transglutaminase and endomysial antibody.

RESULTS

Both the endomysial antibody and tissue transglutaminase antibody have very high sensitivities (93% for both) and specificities (>99% and >98% respectively) for the diagnosis of typical coeliac disease with villous atrophy. Human recombinant tissue transglutaminase performs much better than guinea pig tissue transglutaminase. Review of studies comparing endomysial antibody with human recombinant tissue transglutaminase antibody shows that endomysial antibody more often has a higher specificity and human recombinant tissue transglutaminase antibody more often has a higher sensitivity.

CONCLUSION

The human recombinant tissue transglutaminase antibody is the preferred test for screening asymptomatic people and for excluding coeliac disease in symptomatic individuals with a low pretest probability (i.e. <25%) for coeliac disease. Furthermore, it has a number of practical and financial advantages. If the pretest probability is >25%, biopsy is preferred as the post-test probability of coeliac disease with a negative test is still >2%.

Diagnostic accuracy of coeliac serological tests: a prospective study

OBJECTIVE

The best way to test serologically for coeliac disease (CD) remains controversial, with endomysial (EMA), transglutaminase (TTG), and gliadin antibodies (AGA) being assessed in various combinations with no apparent standardization. The objective of this study was to evaluate whether TTG-IgA+/-TTG-IgG could be used as a replacement for endomysial antibodies as a reliable screen for CD in patients presenting to a major Australian tertiary referral hospital for assessment of symptoms consistent with CD.

METHODS

Individuals referred for gastroscopic assessment of possible CD were prospectively evaluated by duodenal biopsy assessment. The following diagnostic methods were compared: dual-isotype transglutaminase (TTG-dual), combined-isotype transglutaminase (TTG-IgA+G), TTG-IgA, combined-isotype gliadin antibodies (AGA-IgA+G), AGA-IgA, and endomysial antibody assays. Clinical performance characteristics (sensitivity, specificity, area under the curve for receiver-operating characteristic analysis; AUROC) were assessed for all kits.

RESULTS

The correlation between transglutaminase kits was generally good, with the best transglutaminase kit demonstrating high correlation (r=0.86) with endomysial antibodies. A comparison of different types of endomysial antibody assays displayed variable diagnostic performance (sensitivity 61.90-68.42%; specificity 80.00-98.57%; AUROC 0.71-0.83). Sensitivity (90.48-92.31%), specificity (80.77-82.89%) and AUROC values (0.92-0.94) for dual-isotype transglutaminase kits displayed narrow ranges. AGA assays were less sensitive (AGA-IgA: 42.31-46.15%; AGA-IgG: 61.54%) and less specific (AGA-IgA: 85.09-87.73%; AGA-IgG: 82.46-84.09%). Dual-isotype transglutaminase testing was diagnostically equivalent to transglutaminase-IgA (AUROC 0.92 versus 0.91, P=0.33).

CONCLUSIONS

Our study suggests that transglutaminase screening (using the IgA+/-IgG isotype) is a sensitive and specific alternative to endomysial antibody testing in the serological assessment of CD. On the basis of our findings, AGA antibody testing no longer appears to be an essential part of the diagnostic strategy for adult CD.

Coeliac disease: a diverse clinical syndrome caused by intolerance of wheat, barley and rye

Coeliac disease is a lifelong intolerance to the gluten found in wheat, barley and rye, and some patients are also sensitive to oats. The disease is genetically determined, with 10% of the first-degree relatives affected and 75% of monozygotic twins being concordant. Of the patients with coeliac disease 95% are human leucocyte antigen (HLA)-DQ2 or HLA-DQ8 positive. Characteristically, the jejunal mucosa becomes damaged by a T-cell-mediated autoimmune response that is thought to be initiated by a 33-mer peptide fragment in A2 gliadin, and patients with this disorder have raised levels of anti-endomysium and tissue transglutaminase antibodies in their blood. Coeliac disease is the major diagnosable food intolerance and, with the advent of a simple blood test for case finding, prevalence rates are thought to be approximately 1:100. Classically, the condition presented with malabsorption and failure to thrive in infancy, but this picture has now been overtaken by the much more common presentation in adults, usually with non-specific symptoms such as tiredness and anaemia, disturbance in bowel habit or following low-impact bone fractures. Small intestinal biopsy is necessary for diagnosis and shows a characteristically flat appearance with crypt hypoplasia and infiltration of the epithelium with lymphocytes. Diet is the key to management and a gluten-free diet effectively cures the condition. However, this commitment is lifelong and many aisles in the supermarket are effectively closed to individuals with coeliac disease. Compliance can be monitored by measuring antibodies in blood, which revert to negative after 6-9 months. Patients with minor symptoms, who are found incidentally to have coeliac disease, often ask whether it is necessary to adhere to the diet. Current advice is that dietary adherence is necessary to avoid the long-term complications, which are, principally, osteoporosis and small bowel lymphoma. However, risk of these complications diminishes very considerably in patients who are on a gluten-free diet.

Celiac disease

Celiac disease is a chronic intestinal disease caused by intolerance to gluten. It is characterized by immune-mediated enteropathy, associated with maldigestion and malabsorption of most nutrients and vitamins. In predisposed individuals, the ingestion of gluten-containing food such as wheat and rye induces a flat jejunal mucosa with infiltration of lymphocytes. The main symptoms are: stomach pain, gas, and bloating, diarrhea, weight loss, anemia, edema, bone or joint pain. Prevalence for clinically overt celiac disease varies from 1:270 in Finland to 1:5000 in North America. Since celiac disease can be asymptomatic, most subjects are not diagnosed or they can present with atypical symptoms. Furthermore, severe inflammation of the small bowel can be present without any gastrointestinal symptoms. The diagnosis should be made early since celiac disease causes growth retardation in untreated children and atypical symptoms like infertility or neurological symptoms. Diagnosis requires endoscopy with jejunal biopsy. In addition, tissue-transglutaminase antibodies are important to confirm the diagnosis since there are other diseases which can mimic celiac disease. The exact cause of celiac disease is unknown but is thought to be primarily immune mediated (tissue-transglutaminase autoantigen); often the disease is inherited. Management consists in life long withdrawal of dietary gluten, which leads to significant clinical and histological improvement. However, complete normalization of histology can take years.

Do we need to measure total serum IgA to exclude IgA deficiency in coeliac disease?

BACKGROUND

Screening for IgA deficiency in patients with coeliac disease is essential because of the increased incidence of IgA deficiency associated with the disease, which usually relies on the estimation of IgA levels in each case.

AIM

To devise a method of excluding IgA deficiency without measuring total serum IgA in each case.

MATERIALS AND METHODS

The optical density readings on enzyme-linked immunosorbent assay (ELISA) of 608 routine samples received for tissue transglutaminase (TTG) antibody testing for coeliac disease were compared with their total IgA concentrations. Dilution experiments were also carried out to ensure linear relationships between optical density on ELISA and IgA concentrations and to compare the sensitivities for TTG and endomysium antibodies in TTG-positive samples.

RESULTS AND DISCUSSION

A clear relationship was shown between total IgA concentration and TTG optical density readings by ELISA. To ensure a positive TTG result if antibodies are present, it was possible to recommend an optical density level above which all samples have sufficient IgA. Samples with optical density <0.05 should be investigated further by estimating total IgA and, if low, samples should be subjected to immunofluorescence microscopy testing for IgA and IgG endomysium antibodies.

CONCLUSIONS

An easier, more cost-effective and practical way of excluding IgA deficiency in the investigation on coeliac disease is reported.