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

IgA Deficiency Is Not Systematically Ruled Out in Patients Undergoing Celiac Disease Testing

BACKGROUND

Guidelines for celiac disease (CD) testing recommend total serum IgA determination alongside anti-transglutaminase IgA antibodies. It is not well known if lack of serum IgA determination is a common finding in clinical practice.

AIM

To determine the prevalence of lack of serum IgA determination among patients screened for celiac disease.

MATERIALS AND METHODS

We identified all subjects who underwent serum anti-transglutaminase IgA and/or other CD-related antibodies determination at a single teaching hospital in Buenos Aires from October 2019 to February 2020. Medical records were reviewed to select adult patients who were tested for celiac disease. The primary outcome was the proportion of patients with inadequate testing for celiac disease due to lack of serum IgA determination. We retrieved the following variables from each patient's record: age, gender, body mass index, symptoms present at screening, first-grade family history of CD, history of type-1 diabetes mellitus, autoimmune hypothyroidism, Down's syndrome.

RESULTS

Overall, 1122 patients were included for analysis. Lack of serum IgA determination prevalence was 20.49%. Among patients who did have serum IgA determination, the prevalence of IgA deficiency was 5.16%. The following variables were independently associated with a significantly increased odds of serum IgA determination: diarrhea [OR 1.55 (1.01-2.34)] and abdominal pain [OR 2.28 (1.44-3.63)]; higher body mass index [OR 0.91 (0.85-0.98)], osteoporosis [OR 0.49 (0.28-0.89)], hypothyroidism [OR 0.18 (0.07-0.45)], arthralgia/arthritis [OR 0.47 (0.27-0.85)], or testing by endocrinologist [OR 0.46 (0.23-0.91)] and gynecologist [OR 0.14 (0.06-0.31)] were inversely associated.

CONCLUSION

IgA deficiency is not systematically ruled out in a relatively high proportion of patients undergoing serological screening of celiac 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.

Innate Mechanisms in Selective IgA Deficiency

Selective IgA deficiency (SIgAD), characterized by a serum IgA level below 0.07 mg/ml, while displaying normal serum levels of IgM and IgG antibodies, is the most frequently occurring primary immunodeficiency that reveals itself after the first four years after birth. These individuals with SIgAD are for the majority healthy and even when they are identified they are usually not investigated further or followed up. However, recent studies show that newborns and young infants already display clinical manifestations of this condition due to aberrancies in their immune defense. Interestingly, there is a huge heterogeneity in the clinical symptoms of the affected individuals. More than 50% of the affected individuals do not have clinical symptoms, while the individuals that do show clinical symptoms can suffer from mild to severe infections, allergies and autoimmune diseases. However, the reason for this heterogeneity in the manifestation of clinical symptoms of the individuals with SIgAD is unknown. Therefore, this review focusses on the characteristics of innate immune system driving T-cell independent IgA production and providing a mechanism underlying the development of SIgAD. Thereby, we focus on some important genes, including TNFRSF13B (encoding TACI), associated with SIgAD and the involvement of epigenetics, which will cover the methylation degree of TNFRSF13B, and environmental factors, including the gut microbiota, in the development of SIgAD. Currently, no specific treatment for SIgAD exists and novel therapeutic strategies could be developed based on the discussed information.

The Epidemiology and Clinical Manifestations of Autoimmunity in Selective IgA Deficiency

Selective immunoglobulin A deficiency (SIgAD) is the most common primary immunodeficiency, defined as an isolated deficiency of IgA (less than 0.07 g/L). Although the majority of people born with IgA deficiency lead normal lives without significant pathology, there is nonetheless a significant association of IgA deficiency with mucosal infection, increased risks of atopic disease, and a higher prevalence of autoimmune disease. To explain these phenomena, we have performed an extensive literature review to define the geoepidemiology of IgA deficiency and particularly the relative risks for developing systemic lupus erythematosus, hyperthyroidism, hypothyroidism, type 1 diabetes mellitus, Crohn's disease, ulcerative colitis, rheumatoid arthritis, juvenile idiopathic arthritis, ankylosing spondylitis, and vitiligo; these diseases have strong data to support an association. We also note weaker associations with scleroderma, celiac disease, autoimmune hepatitis, immune thrombocytopenic purpura, and autoimmune hemolytic anemia. Minimal if any associations are noted with myasthenia gravis, lichen planus, and multiple sclerosis. Finally, more recent data provide clues on the possible immunologic mechanisms that lead to the association of IgA deficiency and autoimmunity; these lessons are important for understanding the etiology of autoimmune disease.

Implementation of National Institute for Health and Care Excellence (NICE) guidance to measure immunoglobulin A with all coeliac screens: can an affordable solution be devised?

There has been a dramatic increase in requests for coeliac disease (CD) serological screening using immunoglobulin (Ig)A tissue transglutaminase antibodies (IgA-tTG). Recently, the UK National Institute for Health and Care Excellence has revised its guidance, recommending that total IgA should also be measured in all samples. This is justified, as false-negative results may occur with IgA deficiency. However, implementation of this guidance will incur considerable expense. Tests that measure IgA-tTG antibodies can detect IgA deficiency, indicated by low background signal. This provides an opportunity to identify samples containing IgA ≤ 0·2g/l, obviating the need for unselected IgA measurement. We investigated the feasibility of this approach in two centres that use the EliA™ Celikey™ assay or QUANTA Lite^® enzyme-linked immunosorbent assay to quantify IgA-tTG antibodies. In both cases, total IgA correlated strongly with background IgA-tTG assay signal. Using the Celikey™ assay, a threshold of < 17·5 response units achieved 100% sensitivity (95% confidence intervals 79·4-100%) for detection of IgA ≤ 0·2g/l, circumventing the need for IgA testing in > 99% of sera. A similar principle was demonstrated for the QUANTA Lite^® assay, whereby a threshold optical density of < 0·0265 also achieved 100% sensitivity (95% confidence intervals 78·2-100%) for IgA ≤ 0·2 g/l, avoiding unnecessary IgA testing in 67% of cases. These data suggest that CD screening tests can identify samples reliably containing low IgA in a real-life setting, obviating the need for blanket testing. However, this approach requires careful individualized validation, given the divergent efficiency with which assays identify samples containing low IgA.

[Autoimmune diseases and autoantibodies in pediatric patients and their first-degree relatives with immunoglobulin A deficiency]

INTRODUCTION

Clinical manifestations of Immunoglobulin A Deficiency (IgAD) include recurrent infections, atopy and autoimmune diseases. However, to our knowledge, the concomitant evaluations of autoimmune diseases and autoantibodies in a cohort of IgAD patients with current age > 10 years-old and their relatives have not been assessed.

OBJECTIVES

To evaluate autoimmune diseases and the presence of autoantibodies in IgAD patients and their first-degree relatives.

METHODS

A cross-sectional study was performed in 34 IgAD patients (current age > 10 years-old) and their first-degree relatives. All of them were followed at a tertiary Brazilian primary immunodeficiency center: 27 children/adolescents and 7 of their first-degree relatives with a late diagnosis of IgAD. Autoimmune diseases and autoantibodies (antinuclear antibodies, rheumatoid factor, and anti-thyroglobulin, anti-thyroperoxidase and IgA class anti-endomysial antibodies) were also assessed.

RESULTS

Autoimmune diseases (n=14) and/or autoantibodies (n=10, four of them with isolated autoantibodies) were observed in 18/34 (53%) of the patients and their relatives. The most common autoimmune diseases found were thyroiditis (18%), chronic arthritis (12%) and celiac disease (6%). The most frequent autoantibodies were antinuclear antibodies (2%), anti-thyroglobulin and/or anti-thyroperoxidase (24%). No significant differences were observed in the female gender, age at diagnosis and current age in IgAD patients with and without autoimmune diseases and/or presence of autoantibodies (p>0.05). The frequencies of primary immunodeficiency's in family, autoimmunity in family, atopy and recurrent infections were similar in both groups (p>0.05).

CONCLUSION

Autoimmune diseases and autoantibodies were observed in IgAD patients during follow-up, reinforcing the necessity of a rigorous and continuous follow-up during adolescence and adulthood.

Laboratory clues to immunodeficiency; missed chances for early diagnosis?

Primary immunodeficiency is seen in an estimated one in 1200 people, and secondary immunodeficiency is increasingly common, particularly with the use of immunosuppresion, cancer therapies and the newer biological therapies such as rituximab. Delays in the diagnosis of immunodeficiency predictably lead to preventable organ damage. Examples of abnormal pathology tests that suggest immunodeficiency from all laboratory specialities are given, where vigilant interpretation of abnormal results may prompt earlier diagnosis. If immunodeficiency is suspected, suggested directed testing could include measuring immunoglobulins, a lymphocyte count and T-cell and B-cell subsets.

Tissue transglutaminase antibody levels predict IgA deficiency

OBJECTIVE

Measuring serum tissue transglutaminase immunoglobulin A (tTG IgA) levels is the most widely used screening test for coeliac disease. However, given an increased prevalence of IgA deficiency among coeliac patients there is a risk of false negative results. Hence, in addition to specific serum tTG IgA, screening tests frequently include total IgA levels. The objective of this study was to determine whether tTG IgA antibody levels might be used to predict IgA deficiency and hence avoid unnecessary testing of total IgA levels in all individuals.

DESIGN

Retrospective analysis of 9429 serum tTG IgA and corresponding total IgA levels obtained from children and young adults in the East of England between 2007 and 2011.

RESULTS

The overall prevalence of IgA deficiency was found to be very low with only 0.9% of individuals affected. Using receiver operating characteristic curve analysis we identified a cut-off value for tTG IgA of ≥0.10 μ/mL to be predictive for the absence of total IgA deficiency (IgA<0.06 g/L). Specifically, using this cut-off value, total IgA deficiency could be excluded with a sensitivity of 0.92 and specificity of 0.84. In our cohort, only 16.4% of our patient sample would have needed total IgA measurement to rule out a false negative result due to IgA deficiency.

CONCLUSIONS

Our data provide a simple means of avoiding unnecessary total IgA measurements in the assessment of coeliac disease. By using tTG IgA value quantitatively, only values <0.10 μ/mL require total IgA measurements to rule out IgA deficiency and hence a potentially false negative screening result.

Serological testing for coeliac disease in Type 1 diabetes mellitus: is immunoglobulin A level measurement necessary?

AIMS

Immunoglobulin A (IgA) measurement is advocated when case finding for coeliac disease in patients with Type 1 diabetes mellitus. Currently, there is a paucity of contemporary studies assessing IgA deficiency in Type 1 diabetes. This study evaluates the prevalence of IgA deficiency in individuals with Type 1 diabetes, compared with patients with coeliac disease and control subjects. In addition, we evaluate whether routine IgA measurement is justifiable when case finding for coeliac disease in patients with Type 1 diabetes.

METHODS

All patients were assessed using IgA endomysial antibodies, IgA anti-tissue transglutaminase antibodies and total IgA levels. Altogether, 2434 individuals were tested: 1000 patients with Type 1 diabetes, 234 patients with coeliac disease and 1200 population control subjects. Definitive IgA deficiency was defined as total IgA levels < 0.07 g/l.

RESULTS

The prevalence of IgA deficiency was significantly more common in patients with Type 1 diabetes (0.9%, n = 9/1000; P = 0.036) and coeliac disease (1.29%, n = 3/234; P = 0.041) when compared with population control subjects (prevalence of 0.17%, 2/1200). No statistical difference between Type 1 diabetes and coeliac disease for IgA deficiency was identified (P = 0.87). Of patients in the group with Type 1 diabetes, 3.3% (33/1000) had coeliac disease, and of those only one patient had IgA deficiency leading to an antibody-negative presentation. Both IgA-deficient individuals within the population control subjects had normal duodenal biopsies and no relevant symptoms.

CONCLUSIONS

IgA deficiency is more common in Type 1 diabetes compared with population control subjects. Despite this, very few individuals with Type 1 diabetes and IgA deficiency appear to have villous atrophy on biopsy. These outcomes question the practice of routine IgA measurement when case finding for coeliac disease in patients with Type 1 diabetes.

ACG clinical guidelines: diagnosis and management of celiac disease

This guideline presents recommendations for the diagnosis and management of patients with celiac disease. Celiac disease is an immune-based reaction to dietary gluten (storage protein for wheat, barley, and rye) that primarily affects the small intestine in those with a genetic predisposition and resolves with exclusion of gluten from the diet. There has been a substantial increase in the prevalence of celiac disease over the last 50 years and an increase in the rate of diagnosis in the last 10 years. Celiac disease can present with many symptoms, including typical gastrointestinal symptoms (e.g., diarrhea, steatorrhea, weight loss, bloating, flatulence, abdominal pain) and also non-gastrointestinal abnormalities (e.g., abnormal liver function tests, iron deficiency anemia, bone disease, skin disorders, and many other protean manifestations). Indeed, many individuals with celiac disease may have no symptoms at all. Celiac disease is usually detected by serologic testing of celiac-specific antibodies. The diagnosis is confirmed by duodenal mucosal biopsies. Both serology and biopsy should be performed on a gluten-containing diet. The treatment for celiac disease is primarily a gluten-free diet (GFD), which requires significant patient education, motivation, and follow-up. Non-responsive celiac disease occurs frequently, particularly in those diagnosed in adulthood. Persistent or recurring symptoms should lead to a review of the patient's original diagnosis to exclude alternative diagnoses, a review of the GFD to ensure there is no obvious gluten contamination, and serologic testing to confirm adherence with the GFD. In addition, evaluation for disorders associated with celiac disease that could cause persistent symptoms, such as microscopic colitis, pancreatic exocrine dysfunction, and complications of celiac disease, such as enteropathy-associated lymphoma or refractory celiac disease, should be entertained. Newer therapeutic modalities are being studied in clinical trials, but are not yet approved for use in practice. Given the incomplete response of many patients to a GFD-free diet as well as the difficulty of adherence to the GFD over the long term, development of new effective therapies for symptom control and reversal of inflammation and organ damage are needed. The prevalence of celiac disease is increasing worldwide and many patients with celiac disease remain undiagnosed, highlighting the need for improved strategies in the future for the optimal detection of patients.

A new dot immunoassay for simultaneous detection of celiac specific antibodies and IgA-deficiency

BACKGROUND

This study investigated whether a dot immunoassay (DIA) can provide simultaneous detection of anti-tissue transglutaminase (tTG), anti-deamidated gliadin (DG) and total IgA antibodies, as required in the work-up of celiac disease (CD) patients.

METHODS

Celiac disease patients (n=111) consecutively diagnosed from 2001 to 2011 at the Children's Hospital and Institute of Immunology (Technical University Dresden) were tested for anti-tTG, anti-DG and total IgA by enzyme-linked immunosorbent assay (ELISA) and DIA retrospectively. Blood donors (n=45) and non-CD individuals with low IgA serum levels (n=8) were included as controls. Antibodies to endomysial antigens (EmA) were assessed by indirect immunofluorescence (IIF).

RESULTS

Four (3.6%) of 111 CD patients demonstrated an IgA deficiency with total IgA below 50 mg/L by ELISA. Total IgA of the 107 IgA-non-deficient CD patients varied from 70 to 6000 mg/L. All four IgA-deficient CD patients were detected by a reduced reaction control of DIA and demonstrated positive anti-tTG or anti-DG IgG by DIA or ELISA. Detection of anti-tTG and anti-DG by DIA and ELISA showed a very good agreement (IgA: κ=0.972, 0.856, respectively; IgG: 0.921, 0.895, respectively).

CONCLUSIONS

Immunodot assay is a reliable and easy-to-use technique for the detection of IgA-deficient CD patients. Simultaneous assessment of anti-tTG and anti-DG IgA antibodies, and IgA deficiency by DIA can improve the efficacy of CD serology.

Immunoglobulin A deficiency on serological coeliac screening: an opportunity for early diagnosis of hypogammaglobulinaemia

We present a serendipitous case of clinically significant pan-hypogammaglobulinaemia, diagnosed after routine serological testing for possible coeliac disease led first to identification of IgA deficiency (discovered as a low background in IgA-based routine serological screening), and subsequently to confirmed pan-hypogammaglobulinaemia (antibody immunodeficiency). Hypogammaglobulinaemia is a relatively rare diagnosis (estimated at 1 in 36,000), in which delayed diagnosis and treatment are associated with chronic organ damage including bronchiectasis. Routine serological testing for coeliac disease using the IgA anti-tissue transglutaminase (IgA TTG) test is in widespread use and provides an opportunity for early diagnosis of hypogammaglobulinaemia. Routine serological screening for coeliac disease may uncover IgA deficiency, and we suggest that all IgA-deficient cases identified should also be checked for antibody deficiency by quantifying the other immunoglobulins (IgG, IgM).

Benefits and risks of IgA in immunoglobulin preparations

The case of Immunoglobulin A (IgA) in transfusion medicine is unsettled: on one hand IgA is an important component of adaptive immunity and its deficiency may cause disease, on the other its presence in blood products might induce, in rare instances, allergy-like symptoms if not anaphylaxis. The practice with i.v. immunoglobulins currently changes as up to 10% concentrated preparations are given at fast rates hence even trace amounts of IgA contained in these IgG preparations can cause unexpected (side-) effects. Fortunately, the spectrum of sensitive IgA assays, along with anti-IgA screening assays now permits laboratories to narrow down IgA-dependent transfusion reactions to the real cases, in which IgA was the decisive trigger of anaphylaxis, proven or not by the presence of anti-IgA of the IgG or even IgE class. Tolerance to allogenic IgA has recently been reported. The known association of HLA with IgA deficiency (IgAD) has now been completed with an association to the nonsynonymous variant in IFHI1, allowing physicians to more precisely spot recipients at risk for an IgA-dependent transfusion reaction. Our review, along with our own experience here in Switzerland, allows us to conclude that IgA is a beneficial antibody rather than an allergen to be placed at the end of the list of non-infectious transfusion complications such as TRALI, febrile non-hemolytic reactions, purpura or volume overload.

Selective IgA deficiency in autoimmune diseases

Selective immunoglobulin A deficiency (IgAD) is the most common primary immunodeficiency in Caucasians. It has previously been suggested to be associated with a variety of concomitant autoimmune diseases. In this review, we present data on the prevalence of IgAD in patients with Graves disease (GD), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), celiac disease (CD), myasthenia gravis (MG) and rheumatoid arthritis (RA) on the basis of both our own recent large-scale screening results and literature data. Genetic factors are important for the development of both IgAD and various autoimmune disorders, including GD, SLE, T1D, CD, MG and RA, and a strong association with the major histocompatibility complex (MHC) region has been reported. In addition, non-MHC genes, such as interferon-induced helicase 1 (IFIH1) and c-type lectin domain family 16, member A (CLEC16A), are also associated with the development of IgAD and some of the above diseases. This indicates a possible common genetic background. In this review, we present suggestive evidence for a shared genetic predisposition between these disorders.

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.

Diagnostic immunology in celiac disease

Serum autoantibodies to transglutaminase and endomysium are found in the majority of patients with celiac disease, an autoimmune multisystem disorder affecting approximately 1% of Western and Middle-Eastern populations. Detection of these antibodies plays a crucial role in the diagnosis of celiac disease. The aim of this review is to summarize recent publications in this field, with particular focus on the applications and limitations of celiac autoantibody testing in routine clinical practice.

IgG Antibodies against Deamidated Gliadin Peptides for Diagnosis of Celiac Disease in Patients with IgA Deficiency

Background: Assays for IgG antibodies against deamidated gliadin (IgG-anti-dGli) are comparable in performance with tests detecting IgA antibodies against tissue transglutaminase (IgA-anti-tTG) in diagnosing celiac disease (CD). IgA-anti-tTG are absent in IgA deficiency, a condition often associated with CD. In IgA deficiency, IgG-anti-tTG, which have a lower overall diagnostic accuracy, are routinely measured. We examined whether IgG-anti-dGli would be useful for diagnosing CD in patients with IgA deficiency.

Methods: We studied 34 IgA-deficient CD patients, 185 IgA-competent newly diagnosed children with CD, 316 children without CD, 400 adult blood donors, and 6 control IgA-deficient individuals without CD. Anti-dGli and anti-tTG were measured by ELISA, and endomysium antibodies (EmA) were measured by immunofluorescence on monkey esophagus (IgA as well as IgG class for all antibodies). We calculated diagnostic sensitivity (percentage of patients above cutoff with 95% CIs) according to age-specific cutoffs for 95% diagnostic specificity and according to cutoffs proposed by the manufacturer of the assays.

Results: No IgA-deficient CD patients were positive for any IgA-based antibody assay. Diagnostic sensitivity of IgG-anti-tTG was 91.2% (95% CI 76.3%–97.7%) according to age-specific cutoffs and 82.4% (66.1%–92.0%) according to manufacturer cutoffs. The diagnostic sensitivity of IgG-EmA was 75.8% (58.8%–87.4%) and the sensitivity of IgG-anti-dGli was 88.2% (72.8%–95.9%) according to both cutoffs.

Conclusions: IgG-anti-dGli and IgG-anti-tTG have comparable diagnostic sensitivities for IgA-deficient celiac patients. IgG-anti-dGli may be useful for diagnosing CD in IgA-deficient patients.

Symposium 1: Joint BAPEN and British Society of Gastroenterology Symposium on ‘Coeliac disease: basics and controversies’ Coeliac disease in the twenty-first century

Coeliac disease (CD), traditionally perceived as a rare childhood condition presenting with malabsorption, is instead an autoimmune multisystem disorder usually presenting in adulthood, affecting ⩾1% of the population and linked to the genetic expression of human leucocyte antigens (HLA) DQ2 and DQ8. Presentation occurs most often in the 40–60 years age-group, but potentially at any age. Symptoms attributable to the gut or to malabsorption may be mild, non-specific or absent; under one-third of patients have diarrhoea and almost half are overweight. Histological diagnosis no longer requires small intestine villous atrophy. The Marsh classification recognizes increased intraepithelial lymphocytes and crypt hyperplasia with intact villi as part of the gluten enteropathy spectrum, while some individuals have more subtle abnormalities identified only on electron microscopy. Serological testing for CD autoantibodies (to endomysium and tissue transglutaminase) has revolutionized diagnosis, shifting the process towards primary care. However, a substantial number of patients with CD are seronegative, particularly those without villous atrophy. The autoantibody to endomysium may be produced before histological change. The immune response to transglutaminase is crucial to the disease process. An exciting new development is the link between antibodies to organ-specific transglutaminases and clinical presentation; transglutaminases 2 (gut), 3 (skin) and 6 (nervous system). Negative testing for CD does not preclude its development later and HLA testing may allow ‘once and for all’ exclusion. In conclusion, an increasing proportion of patients with CD do not meet the ‘classic’ picture of malabsorption, positive serological testing and villous atrophy. Insisting on all these criteria for diagnosis will result in under diagnosis.

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.

Advances in coeliac disease

PURPOSE OF REVIEW

The number of people diagnosed with coeliac disease continues to rise, and this article critically summarizes recent research into the condition.

RECENT FINDINGS

Much work has been focused on clarifying the molecular pathways involving cytokines in coeliac disease. Such work will yield improved understanding of the complex pathogenesis of coeliac disease and novel therapeutic targets.

SUMMARY

The recent literature predominantly focuses on both elucidating the pathogenesis and improving diagnostic strategies for coeliac disease, but further work into the treatment of coeliac disease is needed.

Autoimmunity in IgA deficiency: revisiting the role of IgA as a silent housekeeper

Both systemic and organ-specific autoimmune diseases are major manifestations of IgA deficiency (IgAD), the most common primary immunodeficiency. In addition, to discuss the clinical findings of IgAD patients, we proposed a hypothesis to explain the high association with autoimmune phenomena. Based on observations, interactions of monomeric IgA with FcalphaRI result in a partial phosphorylation of FcRgamma-associated FcalphaRI, notably in the immunoreceptor tyrosine-based activation motif (ITAM) inducing the recruitment of the SHP-1 tyrosine phosphatase. This leads to deactivation of several activating pathways of the immune system including immunoreceptors that bear ITAM motif and ITAM-independent receptors. Consequently, inflammatory reactions and auto-immune process would be prevented.

Celiac disease: are endomysial antibody test results being used appropriately?

BACKGROUND

The aim of this study was to retrospectively examine how positive IgA-endomysial antibody (EMA) test results for celiac disease were being interpreted and acted on by physicians in the Calgary Health Region.

METHODS

We reviewed consecutive EMA test results, with or without a serum IgA, obtained during a 17-month period. Seropositive tests were cross-referenced to the surgical database to determine the number of patients who underwent intestinal biopsy and the results of the biopsy. We sent questionnaires to the ordering physicians of positive tests with no record of intestinal biopsy.

RESULTS

Among 11,716 EMA tests in 9533 patients, 349 results were positive in 313 patients (3%). Intestinal biopsies were performed in 218 (70%) of the seropositive patients; 194 of them were diagnostic of celiac disease. Celiac disease was also found in 10 EMA-negative patients. Of the 109 positive tests performed in 95 patients with no subsequent biopsy, 28 had appropriate indications to not perform a biopsy; the most common reason being that the test had been ordered to follow up on a previous biopsy-proven diagnosis of celiac disease (n = 21). For 33 other positive test results without a subsequent biopsy, management appeared to be inappropriate, most commonly (n = 21) because of a recommendation to follow a gluten-free diet despite lack of a tissue diagnosis of celiac disease. For the remaining 48 positive EMA results, administrative issues prevented evaluation (n = 19), the patients refused further evaluation (n = 11), or physician surveys were not returned (n = 18).

CONCLUSIONS

Celiac disease affected 2% of patients, with a similar prevalence in male and female patients. Most positive EMA tests (77%) were appropriately managed by physicians. Beginning a gluten-free diet without biopsy or failing to follow up on a positive EMA test remain common errors of management.