Appropriate clinical use of human leukocyte antigen typing for coeliac disease: an Australasian perspective

UK NEQAS and BSHI guideline: Laboratory testing and clinical interpretation of HLA genotyping results supporting the diagnosis of coeliac disease

Coeliac disease is a common immune-mediated inflammatory disorder caused by dietary gluten in genetically susceptible individuals. While the diagnosis of coeliac disease is based on serological and histological criteria, HLA-DQ genotyping can be useful, especially in excluding the diagnosis in patients who do not carry the relevant DQ heterodimers: DQA1*05 DQB1*02, DQB1*03:02 or DQA1*02 DQB1*02 (commonly referred to as DQ2.5, DQ8 and DQ2.2, respectively). External quality assessment results for HLA genotyping in coeliac disease have revealed concerning errors in HLA genotyping, reporting and clinical interpretation. In response, these guidelines have been developed as an evidence-based approach to guide laboratories undertaking HLA genotyping for coeliac disease and provide recommendations for reports to standardise and improve the communication of results.

Severe Hepatitis Complicating Olmesartan Enteropathy: A Case Report

Introduction

Olmesartan, an angiotensin II receptor antagonist, is associated with an uncommon complication of enteropathy that presents insidiously, usually months to years after initial commencement of anti-hypertensive therapy which can be dose-dependent. It has a variable spectrum of clinical presentation but commonly presents as a moderate to severe malabsorptive process with potential severe complications related to poor end-organ perfusion. Lymphocytic gastritis and microscopic colitis are often noted in patients presenting with olmesartan-induced enteropathy; however, hepatic involvement has been less frequently observed.

Case Presentation

We illustrate a case of a 43-year-old female presenting with 2 weeks of profuse non-bloody diarrhea in the context of olmesartan enteropathy which was complicated by an acute severe ischemic and enteropathic hepatopathy.

Conclusion

Our case prompts clinicians to maintain a high index of suspicion in cases presenting with a seronegative enteropathy and concurrent acute liver injury while on olmesartan therapy. Cessation of olmesartan therapy resulted in prompt resolution of diarrheal symptoms and normalization of the acute transaminitis on subsequent three-week follow-up.

Serum anti-tissue transglutaminase IgA and prediction of duodenal villous atrophy in adults with suspected coeliac disease without IgA deficiency (Bi.A.CeD): a multicentre, prospective cohort study

BACKGROUND

Whether coeliac disease in adults can be diagnosed with serology alone remains controversial. We aimed to evaluate the accuracy of serum anti-tissue transglutaminase IgA (tTG-IgA) in the diagnosis of coeliac disease.

METHODS

In this multicentre, prospective cohort study, adult participants (aged ≥18 years) with suspected coeliac disease without IgA deficiency who were not on a gluten-free diet and who had a local serum tTG-IgA measurement, were enrolled from Feb 27, 2018, to Dec 24, 2020, by 14 tertiary referral centres (ten from Europe, two from Asia, one from Oceania, and one from South America) to undergo local endoscopic duodenal biopsy. Local serum tTG-IgA was measured with 14 different test brands and concentration expressed as a multiple of each test's upper limit of normal (ULN), and defined as positive when greater than 1 times the ULN. The main study outcome was the reliability of serum tests for the diagnosis of coeliac disease, as defined by duodenal villous atrophy (Marsh type 3 or Corazza-Villanacci grade B). Histology was evaluated by the local pathologist, with discordant cases (positive tTG-IgA without duodenal villous atrophy or negative tTG-IgA with duodenal villous atrophy) re-evaluated by a central pathologist. The reliability of serum tests for the prediction of duodenal villous atrophy was evaluated according to sensitivity, specificity, positive predictive value, negative predictive value, and the area under the receiver operating characteristic curve (AUC) for categorical and continuous data.

FINDINGS

We enrolled 436 participants with complete local data on serum tTG-IgA and duodenal histology (296 [68%] women and 140 [32%] men; mean age 40 years [SD 15]). Positive serum tTG-IgA was detected in 363 (83%) participants and negative serum tTG-IgA in 73 (17%). Of the 363 participants with positive serum tTG-IgA, 341 had positive histology (true positives) and 22 had negative histology (false positives) after local review. Of the 73 participants with negative serum tTG-IgA, seven had positive histology (false negatives) and 66 had negative histology (true negatives) after local review. The positive predictive value was 93·9% (95% CI 89·2-98·6), the negative predictive value was 90·4% (85·5-95·3), sensitivity was 98·0% (95·3-100·0), and specificity was 75·0% (66·6-83·4). After central re-evaluation of duodenal histology in 29 discordant cases, there were 348 true positive cases, 15 false positive cases, 66 true negative cases, and seven false negative cases, resulting in a positive predictive value of 95·9% (92·0-99·8), a negative predictive value of 90·4% (85·5-95·3), a sensitivity of 98·0% (95·3-100·0), and a specificity of 81·5% (73·9-89·1). Either using the local or central definition of duodenal histology, the positive predictive value of local serum tTG-IgA increased when the serological threshold was defined at increasing multiples of the ULN (p<0·0001). The AUC for serum tTG-IgA for the prediction of duodenal villous atrophy was 0·87 (95% CI 0·81-0·92) when applying the categorical definition of serum tTG-IgA (positive [>1 × ULN] vs negative [≤1 × ULN]), and 0·93 (0·89-0·96) when applying the numerical definition of serum tTG-IgA (multiples of the ULN). Additional endoscopic findings included peptic gastritis (nine patients), autoimmune atrophic gastritis (three), reflux oesophagitis (31), gastric or duodenal ulcer (three), and Barrett's oesophagus (one). In the 1-year follow-up, a midgut ileum lymphoma was diagnosed in a woman on a gluten-free diet.

INTERPRETATION

Our data showed that biopsy could be reasonably avoided in the diagnosis of coeliac disease in adults with reliable suspicion of coeliac disease and high serum tTG-IgA.

FUNDING

None.

Population genetics and external proficiency testing for HLA disease associations

Numerous associations of HLA variants with susceptibility to diseases, namely, those with an immunopathological component, have been described to date. The strongest HLA associations were incorporated into the standard algorithms for the diagnostics. Disease-associated HLA variants are routinely detected by various techniques including DNA-based assays. For the identification of HLA markers or their combinations with the highest diagnostic value and those with frequent clinical indications (e.g., HLA-B*27, -B*57:01, -DQ2/-DQ8, -DQB1*06:02), diagnostic tests that focus on a single or limited number of specific HLA antigens/alleles, have already been developed; the use of complete typing for particular HLA loci is a relevant alternative. Importantly, external proficiency testing (EPT) became an integral part of good laboratory practice for HLA disease associations in accredited laboratories and not only supports correct "technical" identification of the associated HLA variants, but also adequate interpretation of the results to the clinicians. In the present article selected aspects of EPT for HLA disease associations related to population genetics are reviewed and discussed with the emphasis on the optimal level of HLA typing resolution, population-based differences in disease associated HLA alleles within the allelic group, distribution and linkage disequilibrium of HLA alleles in particular populations and interpretation of the presence of less common HLA variants/haplotypes. In conclusion, the laboratories that perform and interpret the tests to the clinicians, producers of the certified diagnostics and EPT providers should consider, among others, the genetic characteristics of the populations in order to optimise the diagnostic value of the tests for disease-associated HLA variants.

The history and evolution of HLA typing external proficiency testing schemes in UK NEQAS for H&I

The UK National External Quality Assessment Service (NEQAS) provide an external proficiency testing (EPT) service for clinical laboratories. UK NEQAS for Histocompatibility and Immunogenetics (H&I) has been providing EPT schemes for over 45 years and has grown during this time to provide 19 EPT schemes. Accurate human leucocyte antigen (HLA) typing is critical to support safe clinical services, including transplantation, therefore high quality, relevant EPT schemes are required as part of a laboratory's quality assurance. This article reviews the development of the HLA typing EPT schemes, from the first HLA phenotyping scheme in 1975, via the first HLA genotyping scheme in 1992, through to the introduction in 2017 of HLA third field assessment results from next-generation sequencing technology. In addition, the introduction of EPT schemes to cover HLA associated diseases and pharmacogenetic reactions, including HLA-B27, HLA*B*57:01 and HLA-DQ for coeliac disease are discussed. The accuracy of laboratory EPT results for HLA phenotyping are >96% (2018-2022), HLA genotyping >99% (2020-2022), HLA-B27 testing >99% (2018-2022) and B*57:01 testing >99% (2017-2022). However, for HLA genotyping for coeliac disease 22%-46% of laboratories made errors in 2020-2022. On investigation, the high rate of unsatisfactory performance was attributed to laboratories lacking specific knowledge to interpret HLA genotyping results and accurately report HLA types for coeliac disease. A misleading commercial kit insert was also identified. The assessment of scheme results has uncovered several issues which have been addressed with the intention of educating participants and improving clinical services. The UK NEQAS for H&I EPT schemes have evolved over the past four decades to reflect changes in HLA typing technology, laboratory clinical practice and to cover post-analytical interpretative elements of HLA typing.

Celiac Disease: Disease Models in Understanding Pathogenesis and Search for Therapy

Celiac disease is a complex polygenic systemic disorder caused by dietary gluten exposure that selectively occurs in genetically susceptible people. The potential celiac disease is defined by the presence of celiac disease-specific antibodies and compatible human leukocyte antigen but without histological abnormalities in duodenal biopsies. At present, the only treatment is lifelong adherence to a gluten-free diet. Despite its effectiveness, the diet is difficult to maintain due to its cost, availability of gluten-free foods, and hidden gluten. The need to develop non-dietary treatment methods is widely recognized, but this is prevented by the absence of a pathophysiologically relevant preclinical model. Nonetheless, in vitro and in vivo models have made it possible to investigate the mechanisms of the disease and develop new treatment approaches: The use of foods with neutralized gluten, microbiota correction, cocktails of specific endoproteinase, polymer gluten binders, specific inhibitors of transglutaminases and inflammatory cytokines, and a vaccine based on allergen-specific therapy.

Review article: Diagnosis of coeliac disease: a perspective on current and future approaches

Diagnostics will play a central role in addressing the ongoing dramatic rise in global prevalence of coeliac disease, and in deploying new non-dietary therapeutics. Clearer understanding of the immunopathogenesis of coeliac disease and the utility of serology has led to partial acceptance of non-biopsy diagnosis in selected cases. Non-biopsy diagnosis may expand further because research methods for measuring gluten-specific CD4+ T cells and the acute recall response to gluten ingestion in patients is now relatively straightforward. This perspective on diagnosis in the context of the immunopathogenesis of coeliac disease sets out to highlight current consensus, limitations of current practices, gluten food challenge for diagnosis and the potential for diagnostics that measure the underlying cause for coeliac disease, gluten-specific immunity.

Combination of HLA-DQ2/-DQ8 Haplotypes and a Single MSH5 Gene Variant in a Polish Population of Patients with Type 1 Diabetes as a First Line Screening for Celiac Disease?

Patients with type 1 diabetes (T1D) are at increased risk for developing celiac disease (CD). The aim of the study was to assess the usefulness of celiac-specific human leukocyte antigen (HLA) haplotype and the rs3130484 variant of MSH5 gene, a previously described non-HLA variant associated with CD in the Polish population as a first-line screening for CD in T1D pediatric patients. Serological CD screening performed in the T1D group (n = 248) and healthy controls (n = 551) allowed for CD recognition in 20 patients (8.1%) with T1D (T1D + CD group). HLA-DQ2, HLA-DQ8 and the rs3130484 variant were genotyped with TaqMan SNP Genotyping Assays. The T1D + CD group presented a higher, but not statistically significant, frequency of HLA-DQ2 in comparison with T1D subjects. Combining the rs3130484 with HLA-DQ2/HLA-DQ8 typing significantly increased the sensitivity of HLA testing from 32.7% to 68.7%, and the accuracy of estimating CD prediction from 51.7% to 86.4% but decreased the specificity from 100% to 78.2%. The receiver operating characteristic curve analysis confirmed the best discrimination for the combination of both genetic tests with an area under curve reaching 0.735 (95% CI: 0.700–0.7690) in comparison with 0.664 (95% CI: 0.632–0.696) for HLA typing alone. Results show the low utility of HLA-DQ2/HLA-DQ8 typing for CD screening in T1D pediatric patients. Combination of the rs3130484 variant of the MSH5 gene and HLA testing increases both the sensitivity and the predictive value of the test accuracy, but still, the obtained values are not satisfactory for recommending such testing as the first-line screening for CD in T1D patients.

Human Leukocyte Antigen (HLA) Typing Study Identifies Maternal DQ2 Susceptibility Alleles among Infertile Women: Potential Associations with Autoimmunity and Micronutrients

BACKGROUND

The interplay between female fertility and autoimmune diseases (AIDs) can involve HLA haplotypes and micronutrients. We analyzed the distribution of HLA-DQ2/-DQ8 in women with infertility or recurrent spontaneous abortion (RSA) and possible associations with AIDs and micronutrient status.

METHODS

Consecutive women (n = 187) with infertility and RSA, and controls (n = 350) were included. All women were genotyped for HLA-DQ2 (DQA1*0201, A1*05, and B1*02) and -DQ8 (DQA1*03 and DQB1*0302) alleles. Serum 25(OH)D, VB12, folate, and ferritin were evaluated.

RESULTS

DQA1*05/B1*02 and the occurrence of at least one DQ2 allele were more prevalent among RSA and infertile women than controls. Infertile women showed lower 25(OH)D and higher prevalence of AIDs than RSA women. In the multivariate analysis, DQA1*05/B1*02 was associated with a significantly higher risk of AIDs in infertile women, and DQA1*05 was independently associated with both 25(OH)D deficiency and AIDs. In RSA women, the presence of AIDs was associated with a significantly higher risk of 25(OH)D deficiency.

CONCLUSION

Our findings showed, for the first time, a higher proportion of DQ2 alleles in infertile and RSA women as compared to controls. Predisposing DQ2 alleles are independent risk factors for AIDs and 25(OH)D deficiency in infertile women and could represent biomarkers for performing early detection of women requiring individually tailored management.

Celiac Disease Management in the United Kingdom Specialist Pediatric Gastroenterology Centers-A Service Survey

OBJECTIVES

The 2012 European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) guidelines on celiac disease (CD) recommended a no-biopsy pathway (NBP) for symptomatic children with high immunoglobin A (IgA)-based anti-tissue transglutaminase (TGA-IgA) titers, positive anti-endomysial antibody and human leukocyte antigen (HLA)-DQ2/DQ8 status. We aimed to understand variations in practice amongst specialist pediatric gastroenterology centers (SPGIC) in the United Kingdom (UK).

METHODS

A survey questionnaire was sent to all UK SPGIC (n = 29) providing endoscopy services for CD diagnosis. It was divided into four main subgroups: analyzing diagnosis of CD through adherence to the ESPGHAN (2012) guidelines, post-diagnosis care and long-term follow-up and discharge from pediatric services.

RESULTS

All 29 responded. NBP was implemented in 28 of 29 centers. Five of 29 centers had already stopped HLA-DQ2/DQ8 testing for NBP diagnosis. Twenty six of 29 centers were performing endoscopy on screening-identified children (mostly asymptomatic, "at-risk" patients). Diagnosis was communicated by a doctor in 65% SPGIC (n = 19). Most centers (n = 23) waited 6-12 months post-diagnosis to start gluten-free oats. Routine vitamin D supplementation was commenced by 4 of 29 centers. All centers repeated TGA-IgA to assess normalization but at varying times post-GFD. Follow-up was with a combination of doctors/dieticians (n = 26). Eleven of 29 centers discharged their patient to primary care.

CONCLUSIONS

There was excellent uptake of ESPGHAN guidelines (2012) in the UK and adherence to guidelines is generally good. Despite published evidence and pragmatic advice from the British Society of Paediatric Gastroenterology Hepatology and Nutrition and National Institute for Health and Care Excellence, significant differences remain in diagnostic and ongoing management practice and are opportunities for research and directive evidence-based follow-up guidance.

Patient factors influencing acute gluten reactions and cytokine release in treated coeliac disease

BACKGROUND

Patients with coeliac disease (CD) commonly report a variety of adverse symptoms to gluten, but descriptions of the symptomatic response in the literature may have been confounded by the presence of food components such as fermentable carbohydrates (FODMAPs) causing symptoms of irritable bowel syndrome independent of gluten. In recent unmasked and masked low FODMAP gluten challenge studies in small groups of treated CD patients, nausea and vomiting were shown to be the key symptoms associated with serum interleukin (IL)-2 release. Our objective was to utilise a large and diverse cohort of people with CD undertaking a standardised gluten food challenge to characterise the demographic, genetic and clinical factors influencing the severity and timing of acute gluten reactions and IL-2 production.

METHODS

A total of 295 adults treated for CD were observed for 6 h after an unmasked food challenge consisting of 10 g vital wheat gluten (low in FODMAPs) in 100 ml water. Assessments included patient-reported outcomes, serum IL-2 and adverse events. Responses were analysed according to patient characteristics, HLA-DQ genotype, duodenal histology and response to a second gluten challenge.

RESULTS

Peak symptom severity was at 3 h (median severity 5/10). Peak IL-2 was at 4 h (median 4 pg/ml, range undetectable to 1028 pg/ml). Older age, older age at diagnosis, HLA-DQ2.5 positivity and homozygosity for HLA-DQB1*02 were each significantly associated with IL-2 elevations after gluten. Patients positive for HLA-DQ2.5, DQ8, DQ2.2 or DQ7 showed elevated IL-2 after gluten. Patient factors were not significantly associated with severity of digestive symptoms, but symptoms were correlated to one another and serum IL-2. Gluten challenge after 5 months caused more vomiting and higher IL-2 levels, but responses correlated with the first.

CONCLUSIONS

Gluten-induced symptoms and cytokine release is common in adults with treated CD. Age, genetics and previous response to gluten predict these acute reactions to gluten challenge. Structured symptom assessment and serum IL-2 after standardised gluten challenge may inform on patient diagnosis, the role of gluten in symptomatology and the need for adjunctive treatment.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT03644069 Registered 21 May 2018.

Improved HLA-based prediction of coeliac disease identifies two novel genetic interactions

Human Leucocyte Antigen (HLA) testing is useful in the clinical work-up of coeliac disease (CD) with high negative but low positive predictive value. We construct a genomic risk score (GRS) using HLA risk genotypes to improve CD prediction and guide exclusion criteria. Imputed HLA genotypes for five European CD case-control GWAS (n > 15,000) were used to construct and validate an interpretable HLA-based risk model (HDQ₁₅), which shows statistically significant improvements in predictive performance upon all previous HLA-based risk models. Conditioning on this model, we find two novel associations, HLA-DQ6.2 and HLA-DQ7.3, that interact significantly with HLA-DQ2.5 (p = 2.51 × 10^-9, 1.99 × 10^-7, respectively). Integrating these novel alleles into a new risk model (HDQ₁₇) leads to predictive performance equivalent or better than the strongest reported GRS (GRS₂₂₈) using 228 single nucleotide polymorphisms (SNPs). We also demonstrate that our proposed HLA-based models can be implemented using only six HLA tagging SNPs with statistically equivalent predictive performance. Using insights from our model to guide exclusionary criteria, we find the positive predictive value of CD testing in high-risk populations can be increased by 55%, from 17.5 to 27.1%, while maintaining a negative predictive value above 99%. Our results suggest that HLA typing is currently undervalued in CD assessment.

Assessment of European Society of Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) guidelines in an Australian paediatric population

Coeliac disease (CD) diagnosis is based on clinical assessment, detection of specific autoantibodies and histological examination of small intestinal biopsies. The European Society of Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) guidelines have recently been updated and recommend CD may be diagnosed without a biopsy or HLA typing in symptomatic patients with high titre IgA tissue transglutaminase antibodies (aTTG) and positive endomysial antibodies (EMA). However, the need for EMA in patients with high level aTTG has been questioned. We aimed to determine the diagnostic benefit of HLA typing, EMA and IgG antibodies to deamidated gliadin (DGP) in children with high level aTTG. We prospectively evaluated children presenting for assessment of possible CD. All patients underwent small bowel biopsy, serological testing and HLA typing. Results were analysed and correlated with histopathological diagnosis. A total of 209 children were assessed; 61.5% were found to have CD and 29% could have avoided biopsy as per 2020 ESPGHAN guidelines. Titres of aTTG ≥60 U/mL or DGP ≥28 U/mL gave 100% specificity and 100% positive predictive value (PPV) for CD. HLA typing and EMA did not improve the PPV of patients with aTTG ≥60 U/mL, but addition of DGP ≥28 U/mL improved diagnostic sensitivity whilst retaining 100% specificity. Addition of HLA and EMA testing in patients with high titre aTTG antibodies does not improve diagnostic performance and may possibly be omitted from the serological workup in these patients. Our data support combining aTTG and DGP testing and optimising cut-offs to maximise specificity as an alternative biopsy-free diagnostic approach.

The Usefulness of Genotyping of Celiac Disease-Specific HLA among Children with Type 1 Diabetes in Various Clinical Situations

AIM

The aim of the study was to determine the usefulness of HLA DQ2/DQ8 genotyping in children with T1D in various clinical situations: as a screening test at the diabetes onset, as a verification of the diagnosis in doubtful situations, and as a test estimating the risk of CD in the future. Materials and methods. Three groups of patients with T1D were included: newly diagnosed (n = 92), with CD and villous atrophy (n = 92), with CD and villous atrophy (n = 92), with CD and villous atrophy (n = 30), and with potential CD (n = 23). Genetic tests were performed (commercial test, PCR, and REX), and clinical data were collected.

RESULTS

The results of genetic tests confirmed the presence of DQ2/DQ8 in 94% of children with diabetes (group I) and in 100% of children with diabetes and CD (groups II and III, respectively). Comparative analysis of the HLA DQ2/DQ8 distribution did not show any differences. Allele DRB1^∗04 (linked with HLA DQ8) was significantly less common in children with diabetes and CD (group I versus groups II and III, 56.5% vs. 24.5%; p = 0.001). The probability of developing CD in DRB1^∗04-positive patients was 4 times lower (OR 0.25; 95% CI 0.118-0.529; p = 0.001). The probability of developing CD in DRB1^∗04-positive patients was 4 times lower (OR 0.25; 95% CI 0.118-0.529; p = 0.001). The probability of developing CD in DRB1^∗04-positive patients was 4 times lower (OR 0.25; 95% CI 0.118-0.529.

CONCLUSIONS

Genotyping HLA DQ2/DQ8 as a negative screening has limited use in assessing the risk of CD at the diabetes onset and does not allow to verify the diagnosis of CD in doubtful situations. The presence of the DRB1^∗04 allele modulates the risk of CD and significantly reduces it and can predict a potential form.

Role of HLA-DQ typing and anti-tissue transglutaminase antibody titers in diagnosing celiac disease without duodenal biopsy in type 1 diabetes: A study of the population-based pediatric type 1 diabetes cohort of Western Australia

AIM

The primary aim of the present study was to determine if it is cost effective to use human leukocyte antigen (HLA) typing as a first-line screening test for celiac disease (CD) in children with type 1 diabetes (T1D), as recommended by the European Society of Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN). The second aim was to investigate whether anti-tissue transglutaminase IgA (anti-tTGA) antibodies can be used to diagnose CD without the need for a confirmatory duodenal biopsy in T1D.

METHODS

Data for all T1D patients aged <18 years, who attended the diabetes clinics in Western Australia up to June 2017, were extracted from the Western Australian Children's Diabetes Database (WACDD) and analyzed for their demographic data and CD permissive HLA alleles (DQ2, DQ8, and DQ7). For T1D patients already diagnosed with CD, the mode of diagnosis of CD, anti-tTGA titers, and CD permissive HLA alleles were analyzed.

RESULTS

Of the 936 eligible T1D patients identified, HLA-DQ typing was available for 551 (59%). Of these 551 patients, 504 (91.2%) were positive for celiac permissive HLA alleles. Eight percent (n = 75) of the T1D patients had a co-diagnosis of CD. High anti-tTGA titers were observed in those who were diagnosed with a positive duodenal biopsy.

CONCLUSION

HLA-DQ typing is not cost effective as a first-line screening test for CD in T1D patients because of over-representation of CD permissive HLA alleles in this group. Anti-tTGA titers may be useful in diagnosing CD in T1D without duodenal biopsy, as high levels were found to be strongly predictive of CD.

Comparison of non-invasive tests with invasive tests in the diagnosis of celiac disease

BACKGROUND/AIMS

Today, invasive diagnostic tests are necessary for definite diagnosis of adult celiac disease (CD). However, in selected children patients, the need for invasive tests is ceased. In this study, we evaluated adult patients according to the ESPGHAN (European Pediatric Gastroenterology Hepatology and Nutrition Society) criteria.

METHODS

Thirty-nine patients (aged 17-66) with symptoms of CD were included. Serum samples were tested for total IgA, tTG-IgA (antitissue transglutaminase), tTG-IgG, DGP-IgA (antideamidated gliadin peptide), DGP-IgG, and EMA (endomysial antibodies). HLA-DQ typing was studied with PCR-SSP (sequence-specific primers) method. Biopsy samples were evaluated according to Marsh scoring.

RESULTS

In CD patients, 71.4% (15/21) of the patients were diagnosed without biopsy according to the EPSGHAN criteria but when ESPGHAN's IgA tTG threshold value for children was taken into consideration (>200 IU/mL), the sensitivity decreased to 81%. Celiac disease diagnosed and control groups were compared in terms of HLA tissue types. DQ2.5 homozygous or DQ2.5/DQ2.2 was significantly higher in CD group, and DQ2- or DQ8-negative HLA tissue type was significantly higher in control group.

CONCLUSION

When serological tests, HLA typing, and clinical symptoms are all in favor of CD, biopsy may not be performed in selected adult CD patients.

Validation of a novel single-drop rapid human leukocyte antigen-DQ2/-DQ8 typing method to identify subjects susceptible to celiac disease

Background and Aim

Human leukocyte antigen (HLA)‐DQ2 and/or ‐DQ8 is an essential risk factor for celiac disease (CD). About 90–95% of patients with CD carry HLA‐DQ2/‐DQ8 alleles, and HLA‐DQ typing is considered an additional diagnostic test. Conventional polymerase chain reaction (PCR)‐based HLA‐DQ typing methods are expensive, complex, and a time‐consuming process. We assessed the efficacy of a novel HLA‐DQ typing method, “Celiac Gene Screen,” for the detection of CD‐associated HLA haplotypes.

Methods

To assess the diagnostic performance of the Celiac Gene Screen test, 100 ethylenediaminetetraacetic acid (EDTA) blood samples, already characterized by the conventional HLA‐DQ typing method, that is, PCR sequence‐specific oligonucleotide probes (PCR‐SSOP), a concordance between both the methods were explored. For validity, a further 300 EDTA blood samples with unknown HLA‐DQ status were genotyped using the Celiac Gene Screen test, including 141 samples from CD, 56 first‐degree relatives (FDRs) of CD and 103 samples from controls.

Results

Of the 100 samples with known status of HLA‐DQ alleles, 79 samples were HLA‐DQ2 and/or ‐DQ8 positive, and 21 samples were HLA‐DQ2 and/or ‐DQ8 negative by conventional PCR. These 100 samples were re‐typed using the Celiac Gene screen kit; all 79 positives were typed positive, and 21 negatives were typed negative for HLA‐DQ alleles. Among 300 samples with unknown HLA‐DQ status, 118 of 141 (84%) patients with CD, 48 of 56 (86%) FDRs of CD, and 52 of 103 (50%) controls typed positive for HLA‐DQ alleles.

Conclusions

The Celiac Gene Screen HLA‐DQ typing method showed excellent concordance with the conventional HLA‐DQ typing method and could be a cost‐reducing and effective method for CD‐associated HLA screening.

An Overview of Celiac Disease in Childhood Type 1 Diabetes

CONTEXT

Celiac disease (CD) is a common phenomenon in children with Type 1 diabetes (T1D). In the present review, we have discussed the pathogenesis, diagnostic biomarkers, risk factors, and prognosis of CD in the context of pediatric T1D.

EVIDENCE ACQUISITION

Literature published in Web of Science, PubMed, Scopus, Google Scholar, and Cochrane Library were scrutinized up to the end of 2017. The keywords of celiac disease, Type 1 diabetes, children, and pediatric were used in different combinations.

RESULTS

Immune cytotoxic reactions along with dampen immune regulatory functions contribute to CD in the context of pediatric T1D. Many children with simultaneous CD and T1D do not represent with the clinical signs of the enteropathy rendering a diagnostic challenge. The most common screening tests in these children are routine serological tests of CD, anti - endomysial, anti - transglutaminase, and anti - deamidated gliadin peptide antibodies. Typing for human leukocyte antigens of DQ - 2 and DQ - 8 may assist in the diagnosis of silent CD in children with T1D. The most significant shared non - HLA genetic loci of CD and T1D comprise CTLA - 4, TAGAP, IL - 18RAP, PTPN2, RGS1, SH2B3, CCR5. Interactions between these loci can be important in susceptibility to CD in T1D. Some new biomarkers have been suggested for diagnosis of CD including ischemia-modified albumin (IMA), soluble syndecan-1 (SSDC-1), regenerating gene Iα (REG-Iα), Neurotensin, and Zonulin, which can be useful for diagnosis and screening of CD in childhood T1D.

CONCLUSIONS

Overall, active seropositive CD seems to be of clinical importance in T1D with significant impacts on the quality of life and predisposition to diabetes associated complications. It is important to detect CD in the context of T1D to prevent potential risks contributing to morbidities and mortalities associated with either CD or T1D.

Food knowledge and psychological state predict adherence to a gluten-free diet in a survey of 5310 Australians and New Zealanders with coeliac disease

BACKGROUND

A gluten-free diet treats coeliac disease, but its efficacy depends on strict adherence. A variety of patient factors may influence adherence but have not been well described at a population level.

AIM

To comprehensively assess the patient factors that influence gluten-free diet adherence in patients with coeliac disease.

METHODS

Patients with coeliac disease completed an online survey comprising the validated Celiac Dietary Adherence Test in addition to data on demographics, details of diagnosis and management and assessment of diet knowledge, quality of life and psychological distress. Survey data were analysed for predictors of adherence and quality of life.

RESULTS

Of 7393 responses, 5310 completed the Celiac Dietary Adherence Test and 3230 (61%) were adherent to a gluten-free diet. Multivariate regression showed older age, being male, symptoms after gluten ingestion, better food knowledge and lower risk of psychological distress were independent predictors of adherence (each P ≤ 0.008). Additionally, dietary adherence was associated with better quality of life (P < 0.001; multiple regression). Respondents who considered themselves to have poor food knowledge were more likely to incorrectly identify gluten-free foods, but could still recognise gluten-containing foods, suggesting that poor knowledge may lead to over-restriction of diet.

CONCLUSIONS

Poor knowledge of a gluten-free diet and psychological wellbeing were independent modifiable risk factors for inadequate adherence to a gluten-free diet in patients with coeliac disease. Involvement of both a dietitian and mental health care professional, in the presence of psychological distress, is likely to be necessary to improve adherence and health outcomes.

High rates of variation in HLA-DQ2/DQ8 testing for coeliac disease: results from an RCPAQAP pilot program

AIM

Coeliac disease(CD) is a highly prevalent, gluten-dependent, autoimmune enteropathy. While the diagnosis is based on serological and histological criteria, genotyping of the human leucocyte antigens (HLA) DQ2 and DQ8 has been shown to have substantial clinical utility, especially in excluding the diagnosis in patients who do not carry either antigen. As a result, HLA genotyping is now being performed by more laboratories and has recently become one of the most frequently requested genetic tests in Australia. To date, there has been little scrutiny on the accuracy and reporting of results by laboratories new to HLA typing. In response to clinician feedback that identified potentially clinically significant discrepancies in HLA typing results, the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) undertook a pilot study to assess laboratory performance in the detection of HLA-DQ2/DQ8 and their associated HLA-DQA1 and HLA-DQB1 alleles.

METHODS

DNA was extracted from 5 patients and sent to 10 laboratories for external quality assurance (EQA) testing. Laboratories were assessed for reporting in genotyping, interpretation and methodology.

RESULTS

Our findings showed that at least 80% of laboratories underperform with respect to recommended guidelines for HLA typing and reporting for CD, with 40% of laboratories failing to provide any clinical interpretation or full genotyping data. This suboptimal level of reporting may lead to ambiguities for downstream clinical interpretation that may compromise patient management.

CONCLUSIONS

These findings highlight the importance of adherence to standardised guidelines for optimal performance and reporting of HLA results and substantiate the need for EQA and proficiency testing for laboratories providing this service.

Rapid, Loop-Mediated Isothermal Amplification Detection of Celiac Disease Risk Alleles

Human leukocyte antigen (HLA) genotyping has become a useful investigation in the diagnostic work-up of celiac disease (CD), with utility in risk stratification and screening. However, broad application of this technology has been hindered by the cost and time burden of conventional laboratory-based assays. We have developed and validated CD-loop-mediated isothermal amplification (CD-LAMP), a LAMP assay, which enables rapid identification of the signature CD risk genotypes, HLA-DQ2.5, HLA-DQ8, HLA-DQ2.2, and HLA-DQA1*05. Sample-to-answer is achieved in approximately 65 minutes without DNA purification, thermal cycling, or specialized analytical equipment. CD-LAMP genotyping of samples was 100% concordant with accredited pathology genotyping on a panel of 40 blood and 20 saliva samples. In a panel of 100 purified DNA samples, genotyping of the high-risk DQ2.5 genotype was 100% concordant with accredited pathology genotyping, with slightly reduced sensitivity for the DQ8 genotype (97.1%) and reduced specificity for the DQ8 (93.9%) and DQ2.2 (95.1%) genotypes. CD-LAMP results are easily visualized and instrument free through the addition of a DNA intercalating dye after amplification. Combined with point-of-care antibody testing, CD-LAMP may enable immediate, confident CD diagnosis at a low cost in the clinical setting.

Resolving incomplete single nucleotide polymorphism tagging of HLA-DQ2.2 for coeliac disease genotyping using digital droplet PCR

A hallmark of coeliac disease (CD) is the exceptionally strong genetic association with HLA-DQ2.5, DQ8, and DQ2.2. HLA typing provides information on CD risk important to both clinicians and researchers. A method that enables simple and fast detection of all CD risk genotypes is particularly desirable for the study of large populations. Single nucleotide polymorphism (SNP)-based HLA typing can detect the CD risk genotypes by detecting a combination of six SNPs but this approach can struggle to resolve HLA-DQ2.2, seen in 4% of European CD patients, because of the low resolution of one negatively predicting SNP. We sought to optimise SNP-based HLA typing by harnessing the additional resolution of digital droplet PCR to resolve HLA-DQ2.2. Here we test this two-step approach in an unselected sample of Mexican DNA and compare its accuracy to DNA typed using traditional exon detection. The addition of digital droplet PCR for samples requiring negative prediction of HLA-DQ2.2 enabled HLA-DQ2.2 to be accurately typed. This technique is a simple addition to a SNP-based typing strategy and enables comprehensive definition of all at-risk HLA genotypes in CD in a timely and cost-effective manner.

Coeliac disease: review of diagnosis and management

Coeliac disease is an immune-mediated systemic disease triggered by exposure to gluten, and manifested by small intestinal enteropathy and gastrointestinal and extra-intestinal symptoms. Recent guidelines recommend a concerted use of clear definitions of the disease. In Australia, the most recent estimated prevalence is 1.2% in adult men (1:86) and 1.9% in adult women (1:52). Active case finding is appropriate to diagnose coeliac disease in high risk groups. Diagnosis of coeliac disease is important to prevent nutritional deficiency and long term risk of gastrointestinal malignancy. The diagnosis of coeliac disease depends on clinico-pathological correlation: history, presence of antitransglutaminase antibodies, and characteristic histological features on duodenal biopsy (when the patient is on a gluten-containing diet). Human leucocyte antigen class II haplotypes DQ2 or DQ8 are found in nearly all patients with coeliac disease, but are highly prevalent in the general population at large (56% in Australia) and testing can only exclude coeliac disease for individuals with non-permissive haplotypes. Adhering to a gluten free diet allows duodenal mucosal healing and alleviates symptoms. Patients should be followed up with a yearly review of dietary adherence and a health check. Non-coeliac gluten or wheat protein sensitivity is a syndrome characterised by both gastrointestinal and extra-intestinal symptoms related to the ingestion of gluten and possibly other wheat proteins in people who do not have coeliac disease or wheat allergy recognised by diagnostic tests.

HLA genotyping as first-line screening tool for coeliac disease in children with juvenile idiopathic arthritis

OBJECTIVES

Coeliac disease (CD) and juvenile idiopathic arthritis (JIA) often coexist. This association warrants assessment for CD in patients with JIA. We evaluated the clinical relevance and cost-effectiveness of human leucocyte antigen (HLA) genotyping in first-line screening for development of CD in children with JIA.

PATIENTS AND INTERVENTIONS

95 patients with JIA were screened for CD using CD-specific antibodies. In case of positivity, a small intestinal biopsy was performed to confirm diagnosis. In addition, HLA genotyping was performed. 110 age-matched and sex-matched Caucasian children from the same geographical area served as controls.

RESULTS

CD was diagnosed in 4 of 95 patients with JIA (4.2%), a rate significantly higher compared with controls (p<0.02) and 14 times higher than in the general population. Twenty-six patients (27.4%) had one of the variants of the risk genotypes. All four patients diagnosed with CD had a HLA-DQ2.5 genotype: one was homozygote, the remainder heterozygote. Twenty-two patients are, judging by their HLA genotypes, at risk of developing CD and require repeated serological screening. None of the 69 patients without HLA-DQ2/DQ8 genotypes had CD-specific antibodies. Screening with HLA genotyping becomes cheaper than screening without after the second determination.

CONCLUSIONS

In our cohort of patients with JIA, lack of HLA-DQ2/DQ8 genotypes identified a majority not at risk of CD in whom repeated serological testing is unnecessary. Genotyping is nowadays the most efficient and cost-effective way to screen for CD risk in JIA.

Mode of Delivery and Risk of Celiac Disease: Risk of Celiac Disease and Age at Gluten Introduction Cohort Study

OBJECTIVE

To determine whether the mode of delivery is associated with the risk of celiac disease (CD) in a cohort of children genetically predisposed to CD prospectively followed from birth.

STUDY DESIGN

By telephone interview, we recorded information on the mode of delivery of children participating in the Risk of Celiac Disease and Age at Gluten Introduction study, a multicenter, prospective intervention trial that compared early and delayed introduction of gluten in infants with at least 1 first-degree relative affected with CD. The human leukocyte antigen genotype was determined at 15 months of age, and serologic screening for CD was performed at 15, 24, and 36 months of age and at 5, 8, and 10 years of age. Patients with positive serologic findings underwent intestinal biopsy. The primary outcome of the current study was the prevalence of CD autoimmunity and overt CD at 5 years of age, according to the mode of delivery.

RESULTS

The study-group included 553 children at CD risk because of positivity for human leukocyte antigen-DQ2, -DQ8, or both. We obtained data on the mode of delivery from 431 of 553 children; 233 of 431 children were born by vaginal delivery (54%). At 5 years of age, the prevalence of CD autoimmunity or overt CD was not different between children born by cesarean or vaginal delivery (24% and 19%, P = .2; 19% and 14%, P = .2 respectively, by the log-rank test).

CONCLUSIONS

In this cohort of children genetically predisposed to CD, the mode of delivery did not influence the risk of developing CD.

Indications for gastrointestinal endoscopy in childhood

Endoscopic examination of the gastrointestinal tract (GIT) for diagnostics and therapy in children has evolved markedly over the last 20 or so years and is now usually undertaken by paediatric endoscopists. Updated diagnostic and management guidelines for common disorders including coeliac disease, gastro-oesophageal reflux disease, eosinophilic oesophagitis and inflammatory bowel disease highlight the central role of endoscopy. Therapeutic endoscopic approaches are also now widely available and further broaden the referral spectrum to include treatment of GIT bleeding, gastrostomy insertion, dilation of strictures and polypectomy. Lastly, the advent of newer technologies allows the examination of hitherto inaccessible areas of the GIT such as the mid-small bowel by wireless capsule video-endoscopy and enteroscopy. We summarise recent current practice and clinical guidelines, focussing on the key indications for referrals that are likely to require endoscopic assessment.

Coeliac disease: a unique model for investigating broken tolerance in autoimmunity

Coeliac disease, a prevalent immune-mediated enteropathy driven by dietary gluten, provides an exceptional human model to dissect the genetic, environmental and immunologic factors operating in autoimmunity. Despite the causative antigen being an exogenous food protein, coeliac disease has many features in common with autoimmune disease including a strong HLA class II association and the presence of pathogenic CD4⁺ T cells and autoantibodies. CD8⁺ intraepithelial lymphocytes specifically target and destroy intestinal epithelium in response to stress signals and not a specific antigen. A unique feature of coeliac disease is the ability to remove gluten to induce disease remission and reintroduce it to trigger a memory response. This provides an unparalleled opportunity to study disease-relevant CD4⁺ T cells that have been expanded in vivo. As a result, the causative peptides have been characterised at a level unprecedented for any autoimmune disease. Despite the complexity of the gluten proteome, resistance to gastrointestinal proteolysis and susceptibility to post-translational modification by transglutaminase help shape a restricted repertoire of immunogenic gluten peptides that have high affinity for disease-associated HLA. The critical steps in coeliac disease pathogenesis have been broadly elucidated and provide the basis for experimental therapies in pre-clinical or clinical development. However, little is known about how and why tolerance to gluten sometimes breaks or fails to develop. Understanding the interactions between genes, the environment, gluten immunity and the microbiome may provide novel approaches for the prevention and treatment of disease.

A population-wide applicable HLA-DQ2 and DQ8 genotyping using DNA from dried blood spots and duplex allele-specific qPCR amplification

Genotyping of HLA-DQ2 and DQ8 haplotypes is important for diagnosis or for screening of early risk detection of celiac disease or type 1 diabetes. Usually, venous blood DNA extraction and expensive and time consuming amplification are used, that hinder population-wide studies. We assayed a friendly HLA-DQ2 and DQ8 genotyping procedure using a combination of DNA from dried blood spot (DBS) and duplex allele-specific qPCR amplification using SYBR Green. DNA was extracted using home-made buffers and compared to an extraction commercial kit. Duplex reactions by qPCR were designed using each Tm allele amplicon for reference samples (positive HLA-DQ2 or DQ8) with allele-specific primers. DBS samples from 558 children (7.99 ± 2.47 y) were collected. The DNA final yield obtained by the home-made extractive procedure was higher than from the commercial kit (1.11 ± 0.56 vs 0.23 ± 0.14 μg), while the quality was similar for both DNA samples. There was concordance in the amplification profiles for DNA samples obtained with both methods. All of four alleles from DQ2 and DQ8 haplotypes were accurately identified in duplex reactions. By using DBS samples and DNA extraction home-made procedure, the costs were reduced by 60%. The whole procedure is cost-effective for HLA-DQ2 and DQ8 genotyping.

Coeliac screening in a Scottish cohort of children with type 1 diabetes mellitus: is DQ typing the way forward?

BACKGROUND

Children with type 1 diabetes mellitus (T1DM) are at increased risk of coeliac disease (CD). Recent guidelines indicate coeliac screening should include HLA typing for CD predisposing (DQ2/DQ8) alleles and those negative for these alleles require no further coeliac screening.

METHODS

Children (n=176) with T1DM attending clinics across two Scottish regions were screened for HLA DQ2/DQ8 as part of routine screening. Data collected included the frequency of DQ2/DQ8 genotypes and the additional cost of HLA screening.

RESULTS

Overall, DQ2/DQ8 alleles were identified in 94% of patients. The additional cost of HLA typing was £3699.52 (£21.02 per patient). All patients with known CD (11/176) were positive for DQ2/DQ8 and all were diagnosed with CD within 5 years of T1DM diagnosis.

CONCLUSIONS

The vast majority of children with T1DM have CD-predisposing HLA genotypes limiting the number of patients that can be excluded from further screening. We conclude that HLA genotyping is not currently indicated for CD screening in this population.

Genomic prediction of celiac disease targeting HLA-positive individuals

Background

Genomic prediction aims to leverage genome-wide genetic data towards better disease diagnostics and risk scores. We have previously published a genomic risk score (GRS) for celiac disease (CD), a common and highly heritable autoimmune disease, which differentiates between CD cases and population-based controls at a clinically-relevant predictive level, improving upon other gene-based approaches. HLA risk haplotypes, particularly HLA-DQ2.5, are necessary but not sufficient for CD, with at least one HLA risk haplotype present in up to half of most Caucasian populations. Here, we assess a genomic prediction strategy that specifically targets this common genetic susceptibility subtype, utilizing a supervised learning procedure for CD that leverages known HLA-DQ2.5 risk.

Methods

Using L1/L2-regularized support-vector machines trained on large European case-control datasets, we constructed novel CD GRSs specific to individuals with HLA-DQ2.5 risk haplotypes (GRS-DQ2.5) and compared them with the predictive power of the existing CD GRS (GRS14) as well as two haplotype-based approaches, externally validating the results in a North American case-control study.

Results

Consistent with previous observations, both the existing GRS14 and the GRS-DQ2.5 had better predictive performance than the HLA haplotype approaches. GRS-DQ2.5 models, based on directly genotyped or imputed markers, achieved similar levels of predictive performance (AUC = 0.718-0.73), which were substantially higher than those obtained from the DQ2.5 zygosity alone (AUC = 0.558), the HLA risk haplotype method (AUC = 0.634), or the generic GRS14 (AUC = 0.679). In a screening model of at-risk individuals, the GRS-DQ2.5 lowered the number of unnecessary follow-up tests for CD across most sensitivity levels. Relative to a baseline implicating all DQ2.5-positive individuals for follow-up, the GRS-DQ2.5 resulted in a net saving of 2.2 unnecessary follow-up tests for each justified test while still capturing 90 % of DQ2.5-positive CD cases.

Conclusions

Genomic risk scores for CD that target genetically at-risk sub-groups improve predictive performance beyond traditional approaches and may represent a useful strategy for prioritizing individuals at increased risk of disease, thus potentially reducing unnecessary follow-up diagnostic tests.

Electronic supplementary material

The online version of this article (doi:10.1186/s13073-015-0196-5) contains supplementary material, which is available to authorized users.