Anti-transglutaminase antibodies and the serological diagnosis of coeliac disease

Defining the optimum strategy for identifying adults and children with coeliac disease: systematic review and economic modelling

BACKGROUND

Coeliac disease is an autoimmune disorder triggered by ingesting gluten. It affects approximately 1% of the UK population, but only one in three people is thought to have a diagnosis. Untreated coeliac disease may lead to malnutrition, anaemia, osteoporosis and lymphoma.

OBJECTIVES

The objectives were to define at-risk groups and determine the cost-effectiveness of active case-finding strategies in primary care.

DESIGN

(1) Systematic review of the accuracy of potential diagnostic indicators for coeliac disease. (2) Routine data analysis to develop prediction models for identification of people who may benefit from testing for coeliac disease. (3) Systematic review of the accuracy of diagnostic tests for coeliac disease. (4) Systematic review of the accuracy of genetic tests for coeliac disease (literature search conducted in April 2021). (5) Online survey to identify diagnostic thresholds for testing, starting treatment and referral for biopsy. (6) Economic modelling to identify the cost-effectiveness of different active case-finding strategies, informed by the findings from previous objectives.

DATA SOURCES

For the first systematic review, the following databases were searched from 1997 to April 2021: MEDLINE® (National Library of Medicine, Bethesda, MD, USA), Embase® (Elsevier, Amsterdam, the Netherlands), Cochrane Library, Web of Science™ (Clarivate™, Philadelphia, PA, USA), the World Health Organization International Clinical Trials Registry Platform ( WHO ICTRP ) and the National Institutes of Health Clinical Trials database. For the second systematic review, the following databases were searched from January 1990 to August 2020: MEDLINE, Embase, Cochrane Library, Web of Science, Kleijnen Systematic Reviews ( KSR ) Evidence, WHO ICTRP and the National Institutes of Health Clinical Trials database. For prediction model development, Clinical Practice Research Datalink GOLD, Clinical Practice Research Datalink Aurum and a subcohort of the Avon Longitudinal Study of Parents and Children were used; for estimates for the economic models, Clinical Practice Research Datalink Aurum was used.

REVIEW METHODS

For review 1, cohort and case-control studies reporting on a diagnostic indicator in a population with and a population without coeliac disease were eligible. For review 2, diagnostic cohort studies including patients presenting with coeliac disease symptoms who were tested with serological tests for coeliac disease and underwent a duodenal biopsy as reference standard were eligible. In both reviews, risk of bias was assessed using the quality assessment of diagnostic accuracy studies 2 tool. Bivariate random-effects meta-analyses were fitted, in which binomial likelihoods for the numbers of true positives and true negatives were assumed.

RESULTS

People with dermatitis herpetiformis, a family history of coeliac disease, migraine, anaemia, type 1 diabetes, osteoporosis or chronic liver disease are 1.5-2 times more likely than the general population to have coeliac disease; individual gastrointestinal symptoms were not useful for identifying coeliac disease. For children, women and men, prediction models included 24, 24 and 21 indicators of coeliac disease, respectively. The models showed good discrimination between patients with and patients without coeliac disease, but performed less well when externally validated. Serological tests were found to have good diagnostic accuracy for coeliac disease. Immunoglobulin A tissue transglutaminase had the highest sensitivity and endomysial antibody the highest specificity. There was little improvement when tests were used in combination. Survey respondents (n = 472) wanted to be 66% certain of the diagnosis from a blood test before starting a gluten-free diet if symptomatic, and 90% certain if asymptomatic. Cost-effectiveness analyses found that, among adults, and using serological testing alone, immunoglobulin A tissue transglutaminase was most cost-effective at a 1% pre-test probability (equivalent to population screening). Strategies using immunoglobulin A endomysial antibody plus human leucocyte antigen or human leucocyte antigen plus immunoglobulin A tissue transglutaminase with any pre-test probability had similar cost-effectiveness results, which were also similar to the cost-effectiveness results of immunoglobulin A tissue transglutaminase at a 1% pre-test probability. The most practical alternative for implementation within the NHS is likely to be a combination of human leucocyte antigen and immunoglobulin A tissue transglutaminase testing among those with a pre-test probability above 1.5%. Among children, the most cost-effective strategy was a 10% pre-test probability with human leucocyte antigen plus immunoglobulin A tissue transglutaminase, but there was uncertainty around the most cost-effective pre-test probability. There was substantial uncertainty in economic model results, which means that there would be great value in conducting further research.

LIMITATIONS

The interpretation of meta-analyses was limited by the substantial heterogeneity between the included studies, and most included studies were judged to be at high risk of bias. The main limitations of the prediction models were that we were restricted to diagnostic indicators that were recorded by general practitioners and that, because coeliac disease is underdiagnosed, it is also under-reported in health-care data. The cost-effectiveness model is a simplification of coeliac disease and modelled an average cohort rather than individuals. Evidence was weak on the probability of routine coeliac disease diagnosis, the accuracy of serological and genetic tests and the utility of a gluten-free diet.

CONCLUSIONS

Population screening with immunoglobulin A tissue transglutaminase (1% pre-test probability) and of immunoglobulin A endomysial antibody followed by human leucocyte antigen testing or human leucocyte antigen testing followed by immunoglobulin A tissue transglutaminase with any pre-test probability appear to have similar cost-effectiveness results. As decisions to implement population screening cannot be made based on our economic analysis alone, and given the practical challenges of identifying patients with higher pre-test probabilities, we recommend that human leucocyte antigen combined with immunoglobulin A tissue transglutaminase testing should be considered for adults with at least a 1.5% pre-test probability of coeliac disease, equivalent to having at least one predictor. A more targeted strategy of 10% pre-test probability is recommended for children (e.g. children with anaemia).

FUTURE WORK

Future work should consider whether or not population-based screening for coeliac disease could meet the UK National Screening Committee criteria and whether or not it necessitates a long-term randomised controlled trial of screening strategies. Large prospective cohort studies in which all participants receive accurate tests for coeliac disease are needed.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019115506 and CRD42020170766.

FUNDING

This project was funded by the National Institute for Health and Care Research ( NIHR ) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 44. See the NIHR Journals Library website for further project information.

Frequency of serological markers of rheumatoid arthritis in adult patients with active celiac disease

BACKGROUND

Celiac disease (CD) and rheumatoid arthritis (RA) are multisystem autoimmune diseases affecting 1% of general populationa. Both diseases share genetic and immunological features.

AIM

In this retrospective study, we aim to determine the frequency of auto-antibodies of RA in adult patients with CD.

MATERIALS AND METHODS

Seventy seven adult patients with active CD were included in the present study. Ninety healthy blood donors (HBD) served as control group. Anti-cyclic citrullinated peptides antibodies (CCP-Ab) and rheumatoid factors (RF; IgA, IgG and IgM) were determined by enzyme linked immunosorbent assay (ELISA) for patients and control group. For statistical analysis, we used Chi-square or Fisher's exact test.

RESULTS

Our study included 77 adult patients with active celiac disease (57 female, 20 male). Twenty-four (31.2%) active celiac patients and 7 (7.8%) blood donors had CCP-Ab or RF (31.2% vs 7.8%, p < 10-4). Only two patients (2.6%) had both CCP-Ab and RF. IgA was the predominant isotype of RF in celiac patients (n = 18; 23.4%) while none of healthy blood donors had RF-IgA (23.4% vs 0.0%, p < 10-4).

CONCLUSION

The current study has shown that CD is associated with a high frequency of RF-IgA suggesting that celiac patients could be at a higher risk of developing RA.

Serological screening for celiac disease in children with systemic lupus erythematosus

OBJECTIVE

The aim of the present study was to investigate the frequency of celiac disease (CD) in patients with juvenile systemic lupus erythematosus (JSLE) and the potential association of JSLE and CD.

METHODS

This was a cross-sectional study performed from October 2015 to October 2017. A total of 50 patients with JSLE were included in the study. The levels of total IgA and tissue transglutaminase (tTG) IgA antibody were measured in all patients. Subjects with increased tTG were further evaluated for anti-endomysial antibodies (EMAs). Gastroduodenoscopy and intestinal biopsy were performed in those with increased EMA levels to confirm the diagnosis of CD.

RESULTS

The study included 44 (88.0%) female and 6 (12.0%) male patients. Of the 50 patients, 30 (60.0%) received corticosteroids, and only 4 (8.0%) received no therapy at the time of the study. Only 3 (6.0%) patients were positive for tTG IgA. Patients with positive tTG IgA were then tested for EMA IgA antibodies, and none of them had a positive result.

CONCLUSION

We did not find CD in children with systemic lupus erythematosus. Studies with more patients with JSLE are needed to conclude a more precise result.

Rheumatoid arthritis-celiac disease relationship: joints get that gut feeling

Rheumatoid arthritis (RA) and celiac disease (CD) belong to the autoimmune disease family. Despite being separate entities they share multiple aspects. Epidemiologically they share comparable incidence environmental influences, associated antibodies and a recent incidental surge. They differ in their HLA pre-dispositions and specific predictive and diagnostic biomarkers. At the clinical level, celiac disease exhibits extra-intestinal rheumatic manifestations and RA gastrointestinal ones. Small bowel pathology exists in rheumatic patients. A trend towards responsiveness to a gluten free diet has been observed, ameliorating celiac rheumatic manifestations, whereas dietary interventions for rheumatoid arthritis remain controversial. Pathophysiologically, both diseases are mediated by endogenous enzymes in the target organs. The infectious, dysbiotic and increased intestinal permeability theories, as drivers of the autoimmune cascade, apply to both diseases. Contrary to their specific HLA pre-disposition, the diseases share multiple non-HLA loci. Those genes are crucial for activation and regulation of adaptive and innate immunity. Recently, light was shed on the interaction between host genetics and microbiota composition in relation to CD and RA susceptibility, connecting bugs and us and autoimmunity. A better understanding of the above mentioned similarities in the gut-joint inter-relationship, may elucidate additional facets in the mosaic of autoimmunity, relating CD to RA.

Detection of specific IgA antibodies against a novel deamidated 8-Mer gliadin peptide in blood plasma samples from celiac patients

We studied whether celiac disease (CD) patients produce antibodies against a novel gliadin peptide specifically generated in the duodenum of CD patients by a previously described pattern of CD-specific duodenal proteases. Fingerprinting and ion-trap mass spectrometry of CD-specific duodenal gliadin-degrading protease pattern revealed a new 8-mer gliadin-derived peptide. An ELISA against synthetic deamidated 8-mer peptides (DGP 8-mer) was used to study the presence of IgA anti-DGP 8-mer antibodies in plasma samples from 81 children (31 active CD patients (aCD), 17 CD patients on a gluten-free diet (GFD), 10 healthy controls (C) and 23 patients with other gastrointestinal pathology (GP)) and 101 adults (16 aCD, 12 GFD, 27 C and 46 GP-patients). Deamidation of the 8-mer peptide significantly increased the reactivity of the IgA antibodies from CD patients against the peptide. Significant IgA anti-DGP 8-mer antibodies levels were detected in 93.5% of aCD-, 11.8% of GFD- and 4.3% of GP-patients in children. In adults, antibodies were detected in 81.3% of aCD-patients and 8.3% of GFD-patients while were absent in 100% of C- and GP-patients. Duodenal CD-specific gliadin degrading proteases release an 8-mer gliadin peptide that once deamidated is an antigen for specific IgA antibodies in CD patients which may provide a new accurate diagnostic tool in CD.

Quality not quantity for transglutaminase antibody 2: the performance of an endomysial and tissue transglutaminase test in screening coeliac disease remains stable over time

National Institute of Clinical Excellence (NICE) and European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) guidance for the diagnosis of coeliac disease has been published. However, there is some controversy regarding the advice on the use of stratifying levels of immunoglobulin (IgA) tissue transglutaminase antibody (TG2) test positivity in the absence of test standardization and the vagueness of the indication to test equivocal samples. Using repeat service audit, we demonstrate that a combination of TG2 followed by IgA endomysial antibodies (EMA) is the best strategy for all degrees of mucosal abnormality using our test combination. Reliance upon immunoassay titre is not as effective, and cannot be applied consistently across populations in the absence of assay standardization. Guidelines advocating the use of tests should involve experts in laboratory diagnostics and external quality assurance to ensure that errors of generalization do not occur and that test performance is achievable in routine diagnostic use.

Prevalence of serological markers for celiac disease (IgA and IgG class antigliadin antibodies and IgA class antiendomysium antibodies) in patients with autoimmune rheumatologic diseases in Belo Horizonte, MG, Brazil

CONTEXT

Patients with autoimmune rheumatologic conditions and celiac disease tend to have a variety of autoantibodies, many of which have no clear pathogenic role. The literature contains frequent reports of celiac disease being more prevalent in patients with rheumatologic diseases, although this remains controversial.

OBJECTIVES

To investigate the prevalence of positive serum tests for celiac disease, particularly IgA and IgG antigliadin (AGA) antibodies and IgA antiendomysium antibodies (EmA) in patients with autoimmune rheumatologic diseases. A second aim was to correlate positive serum tests with prednisone and immunosuppressant medication.

METHODS

A total of 190 adults and pediatric patients with a variety of autoimmune rheumatologic diseases (systemic lupus erythematosus, rheumatoid arthritis, juvenile rheumatoid arthritis and spondyloarthrophathies) were evaluated and tested for IgA and IgG antigliadin-antibodies and IgA antiendomysium antibodies. Patients with positive serum tests underwent endoscopic duodenal biopsies for pathology studies.

RESULTS

There were four positive sera (2.1%) for AGA IgA, all of which tested negative for AGA IgG and EmA. Three sera (1.6%) tested positive for AGA IgG; all were negative for AGA IgA and EmA. The EmA test at a 1:2.5 serum dilution tested positive in 94 patients (49.5%); at a 1:5 serum dilution it was positive in 41 patients (21.6%). Eleven subjects tested positive for EmA at 1:40 dilution; and all of these tested negative for IgA tissue antitransglutaminase (tTG) antibodies. Nine of the 11 EmA-positive patients and all 7 patients with positive antigliadin antibodies tests underwent duodenal endoscopic biopsies, and no significant changes were demonstrated in their duodenal mucosa. A positive EmA was associated with elevated optical density AGA IgA readings; however, there was no relationship between positive EmA and AGA IgG optical density readings. Prednisone and immunosuppressant use were unrelated to AGA IgA optical density readings or AGA IgG readings. These drugs were associated with fewer positive EmA tests.

CONCLUSIONS

Positive AGAA, AGAG or EmA results are probably nonspecific for the presence of celiac disease among autoimmune rheumatologic disease patients. The intake of prednisone and immunosuprressant drugs seems to reduce the prevalence of IgA EmA, but it does not interfere with antigliadin antibodies tests.Further studies are required to estimate more accurately the prevalence of this disease in rheumatologic patients.

Prevalence of celiac disease in Egyptian children disputes the east-west agriculture-dependent spread of the disease

OBJECTIVES

Celiac disease (CD) seems to be a common disorder in north Africa; however, to our knowledge no data are yet available on its prevalence in Egypt. This study was undertaken to investigate the frequency of CD in Egyptian children.

PATIENTS AND METHODS

We investigated a sample of the general pediatric population (1500 individuals, 656 girls and 844 boys, age range 7 months to 18 years, median age 8.0 years) (group A); 150 children (age range 6 months to 13 years, median age 16 months) admitted for diarrhea or failure to thrive (group B); and 250 children and adolescents with type 1 diabetes (group C). The screening test was serum class A anti-transglutaminase (anti-tTG) antibody; immunoglobulin A (IgA) antiendomysium, total IgA, and IgG anti-tTG, and small bowel biopsy was performed for confirmation of diagnosis.

RESULTS

In group A, 8 of 1500 children fulfilled the criteria for CD diagnosis; the prevalence of CD was at least 1 in 187 individuals (0.53%; 95% CI 0.17%-0.89%). In group B, 7 of 150 children had CD (4.7%, 95% CI 1.4-7.9). In group C, 16 of 250 sera showed positive results to both the IgA anti-tTG and the IgA antiendomysium test (6.4%; 95% CI 3.4-9.4).

CONCLUSIONS

Celiac disease is a frequent disorder among Egyptian children, both in the general population and in at-risk groups. Therefore, our data do not support the theory of a Middle East-Europe CD prevalence gradient secondary to the pattern of agriculture spreading from the so-called Fertile Crescent.

Antibody responses to deamidated gliadin peptide show high specificity and parallel antibodies to tissue transglutaminase in developing coeliac disease

Coeliac disease (CD) is an enteropathy induced in genetically susceptible individuals by gluten components, gliadin, hordein and secalin, polypeptides present in cereals such as wheat, barley and rye, respectively. Although the disease starts as intolerance to gliadins, antibodies to tissue transglutaminase (tTG) in the gut epithelium are characteristic of the disease. Whereas serum autoantibodies against tTG (tTGA) are highly specific for CD, antibodies to gliadin are less informative as they can also be detected in other enteropathies, and even in healthy individuals. However, it was shown recently that antibodies to certain gliadin peptides occur with high specificity in CD patient sera. We developed a solid phase lanthanide-based immunofluorometric assay for simultaneous detection of serum IgA and IgG antibodies to a synthetic peptide derived from gamma gliadin of wheat comprising amino acids 86-103. Three glutamine residues of this native 18-mer peptide were replaced by glutamic acids and the peptide was biotinylated. Sera from 87 individuals who had undergone duodenal biopsy and were diagnosed with CD and from 81 healthy individuals were analysed for the presence of both IgA and IgG anti-gliadin peptide antibodies. The performance of the peptide AGA assay was excellent, showing a specificity and sensitivity of 90% and 92% for IgA, and 98% and 75% for IgG, respectively. The corresponding values for conventional anti-gliadin antibody (AGA) enzyme-linked immunosorbent assay (ELISA) tests were 72% specificity and 87% sensitivity for IgA, and 64% specificity and 78% sensitivity for IgG. In a prospective study, almost all the tTGA-positive sera drawn from children who later developed CD were also positive for gliadin peptide antibodies.

Recent advances in the understanding of celiac disease: therapeutic implications for the management of pediatric patients

Celiac disease (CD) is an autoimmune condition occurring in genetically susceptible individuals characterized by inflammatory injury to the mucosa of the small intestine after the ingestion of wheat glutens or related barley and rye products. Originally thought to be highly prevalent only in Northern European populations, growing evidence indicates a much higher prevalence in many other regions, including the US as well as South America, North Africa, and Asia. The growing awareness that pediatric patients may present with quite diverse and protean manifestations and the significant impact of CD on childhood development has prompted efforts to increase CD awareness for the early diagnosis and treatment of this disease. The current diagnostic criteria for CD requires characteristic histologic findings in small bowel biopsies and clinical remission when placed on a gluten-free diet. Serologic testing for CD can provide additional support for the diagnosis of CD or a means to assess efficacy and adherence to a gluten-free diet. The mainstay of treatment remains the institution of a gluten-free diet. However, patients with refractory CD may require treatment with immunosuppressant medications. With the increased identification of specific gluten epitopes and understanding of the pathogenesis of CD, future therapies may rely on genetically altering gluten proteins, immunization techniques, or therapies focused on either the development of specific immune tolerance or regulation of mucosal inflammation.

Adult population screening for coeliac disease: comparison of tissue-transglutaminase antibody and anti-endomysial antibody tests

Serological screening tests for coeliac disease have significantly advanced the diagnosis of this condition. The very high specificity (almost 100%) of anti-endomysial antibody detection has been repeatedly confirmed, whereas a lower specificity (90-95%) is found with anti-tissue transglutaminase antibody assays. In the study by Malekzadeh and colleagues, a group of study participants were identified with raised anti-tissue transglutaminase antibodies, but the endomysial antibody test was negative in 86%. Although many of these participants were found to have raised intra-epithelial lymphocytes in their small intestinal mucosa, there is currently insufficient evidence to confidently diagnose gluten-sensitive disease in these patients. Hence, their report that a minimum prevalence of 1:104 of gluten sensitivity is found in the general population of Iran is likely to be an over-estimate and requires confirmation.

Utility in clinical practice of immunoglobulin a anti-tissue transglutaminase antibody for the diagnosis of celiac disease

BACKGROUND & AIMS

The diagnosis of celiac disease often relies on the anti-tissue transglutaminase (tTG) antibody test. The aim of this study was to evaluate its sensitivity and specificity in clinical practice with the use of commercial laboratories, in which the test characteristics might differ from research laboratories.

METHODS

We identified 122 patients with suspected celiac disease who had anti-tTG antibody serologies as well as upper endoscopy with duodenal biopsies. Those with celiac disease were classified as either classic (with diarrhea or other symptoms of malabsorption) or silent (asymptomatic). Biopsies from celiac disease patients were classified as either partial (Marsh IIIA) or total (Marsh IIIB or IIIC) villous atrophy.

RESULTS

The overall sensitivity, specificity, and positive and negative predictive values of the anti-tTG antibody test were 70.6%, 65.0%, 91.1%, and 30.2%, respectively. The sensitivity was 90.0% for patients with total villous atrophy and 42.3% for patients with partial villous atrophy (P < .0001). There were differences in both sensitivity and specificity between the 2 most commonly used commercial laboratories. The sensitivity for Lab #1 was 40.0% versus 86.4% for Lab #2 (P < .0001). The specificity for Lab #1 was 100.0%, and it was 41.7% for Lab #2 (P = .02).

CONCLUSIONS

The sensitivity of the anti-tTG antibody in clinical practice is not as high as previously reported in research laboratories. The sensitivity is significantly lower in patients with partial villous atrophy. There is also significant variability in test characteristics among major commercial laboratories in the United States. These results need to be confirmed in prospective studies.

Calcium activation of tissue transglutaminase in radioligand binding and enzyme-linked autoantibody immunoassays in childhood celiac disease

BACKGROUND

Conflicting data have been published concerning the effect of calcium on binding of autoantibodies to tissue transglutaminase (tTG) in celiac disease (CD).

METHODS

IgA-tTG and IgG-tTG were measured with radioligand binding assays (RBA) using human recombinant (hr) (35)S-tTG produced in lysate of rabbit reticulocytes and with guinea pig (gp) tTG ELISA in 51 CD children (median: 5.7 years) and 35 controls (median: 2.2 years). Assays were performed with and without calcium.

RESULTS

In hr-tTG RBA, IgA-tTG levels remained unchanged after calcium detecting 50/51 CD children and 1/35 controls (p<0.0001). IgG-tTG levels decreased with calcium (p<0.0001) in CD children and detected 48/51 with and 49/51 without calcium as compared to 1/35 controls (p<0.0001). In gp-tTG ELISA, levels increased with calcium (p<0.0001) making it possible to detect an additional three to a total of 50/51 with IgA-tTG and 13 to 39/51 CD children with IgG-tTG compared to 4/35 and 8/35 controls (respectively, p<0.0001). Rabbit reticulocytes displayed calcium-dependent tTG activity.

CONCLUSIONS

Calcium increased binding of IgA-tTG and IgG-tTG in the ELISA test. The reverse effect observed in RBA may be explained by competitive binding between calcium activated native rabbit reticulocyte tTG and hr (35)S-tTG. tTG autoantibody assays may need taking calcium into account for accurate diagnostic sensitivity and specificity for CD.

Immunoglobulin G (IgG) anti-tissue transglutaminase antibodies used as markers for IgA-deficient celiac disease patients

The role of immunoglobulin A (IgA) anti-tissue transglutaminase antibodies (IgA-tTG) as predictors of untreated celiac disease (CoD) is well documented, and the presence and levels of these antibodies are most accurately monitored with native or recombinant human antigens. However, IgA-deficient CoD patients are not identified by IgA serology, and conflicting results concerning the diagnostic validity of IgG antibodies against gliadin (IgG-AGA), endomysium (IgG-EmA), and tTG (IgG-tTG) have been reported. The aim of the present study was to evaluate the utility of IgG-tTG for the detection of CoD in IgA-deficient patients. Samples from 115 IgA-deficient and 200 IgA-sufficient subjects were collected and tested for the presence of IgA and IgG antibodies against tTG, EmA, and AGA. Antibodies against tTG were measured by an enzyme-linked immunosorbent assay based on recombinant human tTG, and antibodies against EmA were determined by immunofluorescence. The values for IgG-tTG showed a higher correlation (correlation coefficient [r] = 0.91) with those for IgG-EmA for the IgA-deficient subjects than for the IgA-sufficient subjects (r = 0.88). The overall concordance of the positive and negative results between IgG-tTG and IgG-EmA was 97%, and the IgG-tTG assay discriminated between IgG-EmA-positive and -negative subjects with IgA deficiency at a rate of 100%. Elevated levels of IgG-tTG and IgG-EmA were measured in 70% of the IgA-sufficient subjects. IgG-tTG detection with recombinant human tTG is a good alternative to IgG-EmA detection, and the addition of IgG-tTG assessment to present screening methods may improve the ability to identify IgA-deficient subjects with CoD.

Marcadores serológicos y genéticos en el diagnóstico y seguimiento de la enfermedad celíaca

INTRODUCTION

Understanding of celiac disease has changed with the advent of serological markers (antigliadin IgA, anti-endomysial IgA and anti-transglutaminase IgA antibodies) and with the identification of major susceptibility genes (HLA-DQA1*05-DQB1*02). Reports of the efficacy of these diagnostic tests have varied, depending on the methodology used and the population investigated.

OBJECTIVES

To determine the clinical utility of genetic and serological markers in the diagnosis of celiac disease, their relationship with histological lesions and their changes during treatment, in order to establish an optimal diagnostic algorithm in our environment.

PATIENTS AND METHODS

We performed a retrospective study of 590 patients from the health area of Badajoz referred to the Immunology Laboratory for screening or follow-up of celiac disease. The results of intestinal histology, serological markers (antigliadin IgA, anti-endomysial IgA and anti-transglutaminase IgA antibodies), and genomic typing (HLA-DQA1*05-DQB1*02) were analyzed.

RESULTS

The sensitivity and specificity of serological tests were greater than 90 %, with a negative predictive value of 98-100 %. HLA-DQA1*05-DQB1*02 was detected in 97 % of celiac patients, with a very high negative predictive value (99 %). On biopsy, 95 % of the patients with some grade of intestinal lesion were positive for antigliadin and/or anti-endomysial antibodies.

CONCLUSION

To avoid missed diagnoses, the diagnostic algorithm of celiac disease should include at least two serological markers (antigliadin antibodies and anti-endomysial and/or anti-transglutaminase antibodies) and IgA quantification. Genomic typing should be carried out if one or more markers are positive or if the subject belongs to any of the risk groups. The physician should decide on the advisability of intestinal biopsy on the basis of the patient's clinical and immunological history.