Phenotypic variance in childhood coeliac disease and the HLA-DQ/DR dose effect

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.

Age-Dependent Trends in the Celiac Disease: A Tertiary Center Experience

OBJECTIVES

Celiac disease (CD) is a common intestinal autoimmune disorder with diverse presenting features. We aimed to determine age-dependent patterns in CD presentation, diagnosis and management at a large tertiary referral center.

METHODS

A retrospective review of electronic medical records of pediatric patients diagnosed with CD between January 1999 and December 2018 at Schneider Children's Medical Center of Israel. We compared demographics, clinical and laboratory parameters between four age groups at CD presentation.

RESULTS

A cohort of 932 children was divided into four groups by age (in years) at diagnosis: 0-3 (17.9%), 3-6 (31.8%), 6-12 (34.5%), 12-18 (15.8%). The youngest age group presented more frequently with diarrhea, weight loss, abdominal distention, vomiting and lower weight z scores, P < 0.01. Hypoalbuminemia and zinc deficiency were also more frequent in this age group, compared to older patients (P < 0.05, each). Rates of anemia were higher in younger age groups (0-3 and 3-6 years), compared to older age groups, P < 0.05. Patients in the younger age groups (0-3 and 3-6 years) presented more frequently with tissue transglutaminase (TTG) levels above 10 times the upper limit of normal (ULN; P < 0.05), and more often normalized their CD serologies by 24 months of gluten-free diets (GFD) compared to older age groups (P < 0.05).

CONCLUSION

There is an age-dependent variation in CD presentation during childhood. Younger patients present more often with malabsorptive features, and higher TTG levels, yet normalize TTG while on GFD more rapidly than older patients. Clinicians should be aware of the diversity in CD presentation and course at the various presentation age.

Does Having Rotavirus Infection in Early Childhood Increase the Risk of Celiac Disease?

Objective With the increasing prevalence of celiac disease (CD) in the population, possible risk factors are under investigation. Environmental and genetic factors that trigger the immune response have been analyzed for many years. This study investigates the presence of CD in children with rotavirus infection. Rotavirus infection is thought to be a risk factor for CD.

Methods Included in the study were 105 of 160 pediatric patients hospitalized due to symptomatic rotavirus infection between 2012 and 2018. These children were screened for CD 45.6 ± 18.2 (14–90) months following the rotavirus infection diagnosed with CD as per ESPGHAN guidelines.

Results A total of 105 pediatric patients who had rotavirus gastroenteritis were included in the study. The age of the children with rotavirus infection was 3.98 ± 1 (2–6) months. In terms of CD, it was 45.6 ± 18.2 months. Around 14 to 90 months later, patients were called for control. CD developed in four (3.8%) of the children with rotavirus, whereas none of the children in the control group developed CD.

Conclusion Rotavirus infection may be a risk factor for CD through immune mechanisms. There are genetic and various environmental factors for the development of CD. Although the CD's occurrence on children who had rotavirus gastroenteritis in our study also supported this situation, there was no statistically significant difference.

The HLA complex and coeliac disease

The Human Leukocyte Antigen (HLA) has a crucial role in the development and pathogenesis of coeliac disease (CD). The genes HLA-DQA1 and HLA-DQB1, both lying in this region and encoding the HLA-DQ heterodimer, are the main genetic predisposing factors to CD. Approximately 90% of CD patients carry the heterodimer HLA-DQ2.5, leaving only a small proportion of patients with lower risk heterodimers (HLA-DQ8, HLA-DQ2.2 or HLA-DQ7.5). These HLA-DQ molecules act as receptors present in the surface of antigen presenting cells and show high affinity for deamidated gluten peptides, which bind and present to CD4⁺ T cells. This triggers the immunological reaction that evolves into CD. Since specific HLA genetics is present in almost the totality of CD patients, HLA typing has a very high negative predictive value, and it can be used to support diagnosis in specific scenarios. HLA risk has been associated to different CD-related features, such as age at onset, clinical outcomes, antibody levels and grade of histological lesion; but further research is needed. HLA-DQ genotypes have been also suggested to modulate the composition of the gut microbiota.

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.

Is the double gene dose of DQ2.5 or DQ2.5/DQ2.2 an involved factor in the clinical features of celiac disease?

Objectives: Celiac disease (CD) is barely known if the quantitative effect of DQB1*02 (DQ2) double dose in antigen presentation to T-cells has translation into the clinic. For this, we have conducted a case-control study in a cohort of two hundred and nineteen patients with CD. Material and methods: For the control group, individuals were enrolled with single dose of DQ2, carrying DQ2.5 heterodimers in heterozygous state (n = 109). The cases with CD were diving into three groups: cases with overall DQ2 double dose (n = 110), DQ2.5 homozygous (n = 33) and DQ2.5/DQ2.2 heterozygous (n = 77). Prevalence and associations of demographic, laboratory, histological and clinical characteristics between the control group and cases were studied. Results: No differences were found for the total of 16 variables analyzed between the control group and overall DQ2 double dose as well as DQ2.5 homozygous cases. In contrast to DQ2.5/DQ2.2, heterozygous cases presented a protection factor for developing allergy to airway allergens regarding the control group (OR = 0.210, p = .019). Conclusions: To date, this negative association has not been described. Further studies will be necessary to elucidate the implication of this protection factor in CD. Since, until now the association between CD and allergic diseases has been poorly studied.

The Phenotype of Celiac Disease Has Low Concordance between Siblings, Despite a Similar Distribution of HLA Haplotypes

The factors determining the presentation of celiac disease are unclear. We investigated the phenotypic concordance and the distribution of human leukocyte antigen (HLA) risk haplotypes in affected siblings. One hundred sibling pairs were included. Clinical and histological parameters and HLA haplotypes were compared between the first diagnosed indexes and their siblings. The phenotype was categorized into gastrointestinal, extra-intestinal, malabsorption/anemia, and asymptomatic. The phenotype was fully concordant in 21 pairs. The most common concordant phenotype was gastrointestinal (14 pairs). Indexes had more anemia/malabsorption and extra-intestinal symptoms than siblings (45% vs. 20%, p < 0.001 and 33% vs. 12%, p < 0.001, respectively). Twenty siblings and none of the indexes were asymptomatic. The indexes were more often women (81% vs. 63%, p = 0.008). They were also more often seronegative (11% vs. 0%, p = 0.03) and younger (37 vs. 43 year, p < 0.001), and had more severe histopathology (total/subtotal atrophy 79% vs. 58%, p = 0.047) at diagnosis. The indexes and siblings were comparable in other disease features. Pairs with discordant presentation had similar HLA haplotypes more often than the concordant pairs. The phenotype was observed to vary markedly between siblings, with the indexes generally having a more severe presentation. HLA did not explain the differences, suggesting that non-HLA genes and environmental factors play significant roles.

HLA-DQ2 homozygosis increases tTGA levels at diagnosis but does not influence the clinical phenotype of coeliac disease: A multicentre study

BACKGROUND AND PURPOSE

Magnitude of gluten-specific T-cell responses in coeliac disease (CD) might be dependent on HLA-DQ2 gene dose. We aimed to investigate the effects of HLA-DQB1*02 allele dose on clinical outcomes.

METHODS

We reviewed the charts of all coeliac patients attending to three Hungarian university clinics after 1997 and included those patients, who (a) were diagnosed with CD, (b) underwent high-resolution HLA typing and (c) were ≥18 years at the time of data collection. HLA typing was performed to determine DQB1*02 allele dose. Patients were divided into risk groups by DQB1*02 allele dose, as follows: high-, intermediate- and low-risk groups corresponded to a double, single and zero doses, respectively. We used ANOVA and Pearson's chi-squared test to explore association between HLA risk and clinical variables.

RESULTS

A total of 727 coeliac patients attended the clinics but only 105 (14.4%) patients were eligible for inclusion. High, intermediate and low HLA risk patients comprised 35.3%, 52.3% and 12.3% of the study population, respectively. Double dose of HLA-DQB1*02 was more frequent in patient with high tTGA level (>10 times the upper limit of normal; p = 0.045). Gene dose was not associated with younger age at diagnosis (p = 0.549), gender (p = 0.739), more severe diagnostic histology (p = 0.318), more frequent classical presentation (p = 0.846), anaemia (p = 0.611), metabolic bone disease (p = 0.374), dermatitis herpetiformis (p = 0.381) and autoimmune diseases (p = 0.837).

CONCLUSIONS

Our study shows a significant gene dose effect in terms of tTGA level at diagnosis, but no significant association between HLA-DQB1*02 allele dose and the clinical outcomes in CD.

Classical celiac disease is more frequent with a double dose of HLA-DQB1*02: A systematic review with meta-analysis

Background and aims

Experimental data suggest that the HLA-DQ2 gene dose has a strong quantitative effect on clinical outcomes and severity of celiac disease (CD). We aimed to conduct a meta-analysis with systematic review to investigate the association between HLA-DQB1*02 gene doses and the characteristics of CD.

Methods

We searched seven medical databases for studies discussing HLA-DQB1 gene dose in CD and various disease characteristics, such as clinical presentation, histology, age at diagnosis, and comorbidities. Odds ratios (OR, for categorical variables) and weighted mean differences (for age) were calculated to compare patients with a double dose of HLA-DQB1*02 versus those with single and zero doses. Heterogeneity was tested with I²-statistics and explored by study subgroups (children and adults).

Results

Twenty-four publications were eligible for meta-analysis. Classical CD was more frequent with a double versus single dose of the HLA-DQB1*02 allele (OR = 1.758, 95%CI: 1.148–2.692, I² = 0.0%). In pediatric studies, gene dose effect was more prominent (OR = 2.082, 95%CI: 1.189–3.646, I² = 0.0% and OR = 3.139, 95%CI: 1.142–8.630, I² = 0.0% for the comparisons of double versus single and double versus zero dose, respectively). Atrophic histology was more prevalent with a double versus zero dose (OR = 2.626, CI: 1.060–6.505, I² = 21.3%). We observed no gene dose effect regarding diarrhea, age at diagnosis, the severity of villous atrophy, and the association with type 1 diabetes mellitus.

Conclusion

A double dose of HLA-DQB1*02 gene seems to predispose patients to developing classical CD and villous atrophy. Risk stratification by HLA-DQB1*02 gene dose requires further clarification due to the limited available evidence.

Repeated Screening Can Be Restricted to At-Genetic-Risk Birth Cohorts

OBJECTIVES

Celiac disease (CD) is associated with tissue transglutaminase autoantibodies (tTGAs) in individuals carrying the human leukocyte antigen (HLA) risk haplotypes DQA1*05:01-DQB1*02:01 (DQ2) and/or DQA1*03:01-DQB1*03:02 (DQ8). The aim of the study was to identify CD in an HLA-genotyped birth cohort prospectively screened for CD.

METHODS

In the initial screening, 13,860 HLA-DQ-genotyped children were invited, of whom 3435/13,860 (25%) accepted participation. Of the 3435, 1620 (47%) carried DQ2 and/or DQ8, of whom 73 (4.5%) were tTGA positive assessed in radioligand-binding assays and 56 (3.5%) developed CD. At age 9 years, 13,024 children from the original cohort were re-invited to follow-up screening using the same study protocol and tTGA assays as in the first screening. Diagnosis of CD was confirmed by intestinal biopsy in children with persistent tTGA.

RESULTS

In the follow-up screening, 1910/4077 (46.8%) carried DQ2 and/or DQ8, of whom 79/1910 (4.1%) were persistently tTGA positive and 72/1907 (3.8%) developed CD. Only 1/2167 (0.05%) child without HLA risk was IgG-tTGA positive, but did not have CD. Of the 980/1910 (51%) children carrying DQ2 and/or DQ8 who were already screened at 3 years of age, 30/979 (3.1%) were diagnosed as new patients at 9 years of age, compared with 42/928 (4.5%) children who did not participate in the initial screening (P = 0.094).

CONCLUSIONS

Screening for CD can be restricted to children carrying HLA-DQ2 and/or DQ8. Repeated screening using tTGA is necessary to identify new patients by 9 years of age. These findings may be relevant when considering implementing screening of the general population.

Coeliac disease and gluten-related disorders in childhood

Gluten-related disorders such as coeliac disease, wheat allergy and noncoeliac gluten sensitivity are increasingly being diagnosed in children. Coeliac disease occurs frequently, affecting 1-3% of the Western population. The condition manifests at a very young age, more so in girls, and is related to the HLA genotype. Coeliac disease might be considered a public health problem and, as primary prevention is not possible, the debate on mass screening should be reopened. Wheat proteins, including gluten, are responsible for one of the most common food allergies in children: wheat allergy. Unlike coeliac disease and wheat allergy, noncoeliac gluten sensitivity is an unclear and controversial entity. These three gluten-related disorders are treated with a gluten-free diet. In coeliac disease, the diet should be strictly followed, whereas wheat allergy only requires wheat elimination and in noncoeliac gluten sensitivity occasional trials of gluten reintroduction can be done. A good diagnostic work-up is important for gluten-related disorders in childhood to avoid unnecessary restrictive diets in children. In this Review, we provide an overview of the pathogenesis, diagnosis and management of the most common gluten-related disorders in children.

Genetics and celiac disease: the importance of screening

The prevalence of celiac disease (CD) is increasing. Despite an increased awareness and an improvement in diagnostic testing, the majority of individuals with CD remain undiagnosed. Currently, genetic testing in screening for CD is used only to exclude a diagnosis or reinforce a strong clinical suspicion. In this paper, we review the most current literature regarding genetic testing in CD. In response to important data revealing that an individual's HLA haplotype is one of the strongest known predictors of CD, we propose genetic screening for at-risk infants to stratify individuals based on genetic risk to ultimately create genetic specific screening algorithms.

Overview of biomarkers for diagnosis and monitoring of celiac disease

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

Biomarkers for diagnosis and monitoring of celiac disease

Celiac disease (CD) is an autoimmune disorder, which damages the small intestine and is caused by ingestion of gluten in genetically susceptible individuals. The only known effective treatment is a lifelong gluten-free diet. Genetic risk factors have been identified and nearly all patients are HLA-DQ2 and/or HLA-DQ8 positive. Specific autoantibodies, IgA antitissue transglutaminase-2, antiendomysium, and antideaminated forms of gliadin peptide antibodies, are widely used as diagnostic aids in celiac patients. However, the discovery of new biomarkers may help in the diagnosis and follow-up of the disease. Recently, the molecule REG Iα, involved in tissue regeneration, has been proposed as a new biomarker of CD. REG Iα expression is increased in the target tissue and in the sera of celiac patients during damage and inflammation, decreasing after gluten-free diet. In this article we review the main biomarkers for diagnosis and monitoring of CD, focusing on the immune response-related mechanisms.

Anaplastic large-cell lymphoma in a child with type I diabetes and unrecognised coeliac disease

Screening for coeliac disease is recommended for children from certain risk groups, with implications for diagnostic procedures and dietetic management. The risk of a malignant complication in untreated coeliac disease is not considered high in children. We present the case of a girl with type I diabetes who developed weight loss, fatigue, and inguinal lymphadenopathy. Four years before, when she was asymptomatic, a screening coeliac tTG test was positive, but gluten was not eliminated from her diet. Based on clinical examination, a duodenal biopsy, and an inguinal lymph node biopsy were performed, which confirmed both coeliac disease and an anaplastic large-cell lymphoma. HLA-typing demonstrated that she was homozygous for HLA-DQ8, which is associated with higher risk for celiac disease, more severe gluten sensitivity, and diabetes susceptibility. She responded well to chemotherapy and has been in remission for over 4 years. She remains on a gluten-free diet. This is the first case reporting the association of coeliac disease, type I diabetes, and anaplastic large-cell lymphoma in childhood. The case highlights the malignancy risk in a genetically predisposed individual, and the possible role of a perpetuated immunologic response by prolonged gluten exposure.

Clinical practice : coeliac disease

Coeliac disease (CD) is an immune-mediated systemic condition elicited by gluten and related prolamines in genetically predisposed individuals and characterised by gluten-induced symptoms and signs, specific antibodies, a specific human leukocyte antigen (HLA) type and enteropathy. The risk of coeliac disease is increased in first-degree relatives, certain syndromes including Down syndrome and autoimmune disorders. It is thought to occur in 1 in 100-200 individuals, but still only one in four cases is diagnosed. Small-bowel biopsy is no longer deemed necessary in a subgroup of patients, i.e. when all of the following are present: typical symptoms or signs, high titres of and transglutaminase antibodies, endomysial antibodies, and HLA-type DQ2 or DQ8. In all other cases, small-bowel biopsy remains mandatory for a correct diagnosis. Therapy consists of a strictly gluten-free diet. This should result in complete disappearance of symptoms and of serological markers. Adequate follow-up is considered essential.

CONCLUSION

Although small-bowel biopsy may be omitted in a minority of patients, small-bowel biopsy is essential for a correct diagnosis of CD in all other cases. Diagnostic work-up should be completed before treatment with gluten-free diet instituted.

Contribution of histological, serological, and genetic factors to the clinical heterogeneity of adult-onset coeliac disease

OBJECTIVE

Although the factors predisposing to coeliac disease (CD) are largely understood, it remains unclear what determines the clinical heterogeneity of the disease. The aim of this study was to explore the contribution of histological, serological, and genetic factors to disease presentation.

MATERIAL AND METHODS

The study was designed as a retrospective chart review of 384 unrelated Caucasian patients diagnosed with CD after the age of 16 at a single UK centre.

RESULTS

We found that 8.8% of IgA-competent CD patients were endomysial antibody (EMA)-negative. Compared with the EMA-positive group, EMA-negative CD patients had a lower prevalence of iron deficiency (52.0% versus 72.6%, p=0.03) and Marsh IIIb-c lesions (66.7% versus 85.3%, p=0.03). Histological severity at diagnosis correlated with anaemia (p<0.01), folate deficiency (p<0.01), and iron deficiency (p=0.05), but no other laboratory or clinical features. Compared with human leucocyte antigen (HLA)-DQ2.5-positive patients, those carrying HLA-DQ2.2 were similar in terms of all the characteristics we considered, whereas those carrying HLA-DQ8 had a lower frequency of EMA positivity (62.5% versus 92.6%, p<0.01). The proportion of EMA-positive patients increased with frequency of the HLA-DQB1*0201 allele (76.7% versus 92.3% versus 96.4% for 0 versus 1 versus 2 alleles, p<0.01); no other evidence of a gene-dose effect of HLA-DQB1*0201 was observed.

CONCLUSIONS

Histological severity at diagnosis of CD is associated with anaemia and some micronutrient deficiencies, but no other clinical features. The proportion of EMA-positive patients is higher amongst those carrying HLA-DQ2 than in those carrying HLA-DQ8, and is highest in HLA-DQ2 homozygotes. We found no correlation between frequency of the HLA-DQ alleles encoding HLA-DQ2.5 and CD severity.