Antigliadin immunoglobulin A best in finding celiac disease in children younger than 18 months of age

The old and new tests for celiac disease: which is the best test combination to diagnose celiac disease in pediatric patients?

BACKGROUND

In the diagnosis of celiac disease (CD), serum assays for anti-endomysium (EMA) and anti-transglutaminase (anti-tTG) antibodies have excellent diagnostic accuracy. However, these assays are less sensitive in young pediatric patients. Recently, a new ELISA test using deamidated gliadin peptides (DGP) as antigen has proved to be very sensitive and specific even in pediatric patients. In addition, anti-actin IgA antibodies (AAA) is another test that can be used in CD patients because antibody concentrations correlate with the degree of villous atrophy. This study evaluated the clinical accuracy of anti-tTG, EMA, AGA, anti-DGP and AAA and the effectiveness of these in different combinations for diagnosing CD in a large cohort of pediatric patients.

METHODS

Sera of 150 children under 6 years of age were tested: 95 patients had a diagnosis of CD, while 55 patients who did not suffer from CD were used as controls. Anti-DGP IgA/IgG and AAA were assayed with ELISA kits, while anti-tTG IgA/IgG and AGA IgG/IgA were assayed using a quantitative fluoroimmunoassay. The EMA test was conducted by indirect immunofluorescence.

RESULTS

Seventy-six of 95 (80%) CD patients were positive for DGP IgA and/or tTG IgA. Eighty of 95 (84.2%) patients were positive for DGP IgG and/or tTG IgA. None of the controls were positive for these antibodies. Eighty-four of 95 (88.4%) patients and 8/55 (14.5%) controls were positive for AAA and/or anti-tTG IgA.

CONCLUSIONS

In very young children, association of anti-tTG IgA with anti-DGP IgG is the best test combination for diagnosing CD, yielding a cumulative sensitivity of 84.2% and a specificity of 100%.

Immunoglobulin G antibodies against deamidated-gliadin-peptides outperform anti-endomysium and tissue transglutaminase antibodies in children <2 years age

To investigate the usefulness of deamidated-gliadin-peptides-antibodies in the diagnosis of celiac disease, serology was tested in 212 children suspected with celiac disease who had undergone a small-intestinal-biopsy. For deamidated-gliadin-peptides-antibodies, two kits were tested. Positive and negative predictive values for IgA deamidated-gliadin-peptides-antibodies using the Bindazyme-kit were 89% and 74%, while the Quanta-Lite-kit had values of 89% and 85%, respectively. For the IgG subtype using the Bindazyme-kit, these values were 85% and 89%, while they were 85% and 91% for the Quanta-Lite-kit. The positive predictive values for endomysium and tissue-transglutaminase antibodies were disappointing (77% and 87%), although the negative predictive values were better (97% and 96%). When the analysis was restricted to the 41 children aged <2 years, no misclassifications occurred with IgG deamidated-gliadin-peptides-antibodies giving 100% accuracy in both kits. The positive predictive value reached 100% for tissue-transglutaminase antibodies and both kits for IgA deamidated-gliadin-peptides-antibodies, while the negative predictive value was 94% in these assays. Positive and negative predictive values for endomysium antibodies were 96% and 93%, respectively. In conclusion, although deamidated-gliadin-peptides-antibodies do not outperform anti-endomysium antibodies in the total study population, the IgG subtype seems to be the best test in children aged <2 years, reaching 100% accuracy.

New screening tests enrich anti-transglutaminase results and support a highly sensitive two-test based strategy for celiac disease diagnosis

BACKGROUND

The identification of specific serological algorithms allowing the diagnosis of celiac disease (CD) is a new challenge for both the clinic and the laboratory. We compared the diagnostic accuracy of three new tests proposed for CD screening with that of the well established IgA tTG, and ascertained whether any combination of these tools might enhance accuracy in diagnosing CD.

METHODS

In sera from 329 CD and 374 control children, the following were assayed: IgA tTG; IgA/IgG, which identify tTG-gliadin complexes (Aeskulisa Celi Check and CeliCheck IgGA); IgA/IgG, which identify deamidated gliadin peptides and tTG (QUANTA Lite(TM) h-tTG/DGP Screen).

RESULTS

When specificity was set at 100%, the most sensitive index of CD was IgA tTG (75.7%, cut-off=100U), followed by QUANTA Lite(TM) h-tTG/DGP Screen (65.3%, cut-off 145U), Aeskulisa Celi Check (62.6%, cut-off 909U/mL) and CeliCheck IgGA (59.6%, cut-off 977U/mL). Three algorithms were obtained by combining IgA tTG with each of the new tests. The algorithm obtained by measuring IgA tTG and QUANTA Lite(TM) h-tTG/DGP Screen allowed the correct identification of CD in 78.7% of cases (negative predictive value=97.3%).

CONCLUSIONS

The two-test based strategy could be used for the cost effective diagnosis of CD.

A biopsy is not always necessary to diagnose celiac disease

OBJECTIVES

Small intestinal histology is the criterion standard for the diagnosis of celiac disease (CD). However, results of serological tests such as anti-endomysium antibodies and anti-tissue transglutaminase antibodies (tTGA) are becoming increasingly reliable. This raises the question of whether a small intestinal biopsy is always necessary. The aim of the present study was, therefore, to investigate whether a small intestinal biopsy can be avoided in a selected group of patients.

PATIENTS AND METHODS

Serology and histological slides obtained from 283 pediatric patients suspected of having CD were examined retrospectively. The response to a gluten-free diet (GFD) in patients with a tTGA level ≥ 100 U/mL was investigated.

RESULTS

A tTGA level ≥ 100 U/mL was found in 128 of the 283 patients. Upon microscopic examination of the small intestinal epithelium, villous atrophy was found in 124 of these patients, confirming the presence of CD. Three patients had crypt hyperplasia or an increased number of intraepithelial lymphocytes. In 1 patient no histological abnormalities were found. This patient did not respond to a GFD.

CONCLUSIONS

Pediatric patients with a tTGA level ≥ 100 U/mL in whom symptoms improve upon consuming a GFD may not need a small intestinal biopsy to confirm CD.

Clinical accuracy of anti-tissue transglutaminase as screening test for celiac disease under 2 years

AIM

To investigate, in patients with suspected celiac disease (CD) younger than 2 years, the clinical value of anti-tissue transglutaminase (tTG) in diagnostic work-up of CD.

METHODS

Between June 2005 and June 2009, 169 patients aged <2 years, with symptoms suggestive of CD, were submitted to biopsy. CD diagnosis was based on the revised criteria of the European Society for Pediatric Gastroenterology, Hepatology and Nutrition.

RESULTS

Of the 169 patients enrolled, 155 were included: 108 of them showed mucosal atrophy and 47 negative histology. Sensitivity and specificity of tTG, at the cut-off of 8 AU/mL, were 0.96 (CI 0.91-0.99) and 0.91 (CI 0.80-0.98), respectively, with likelihood ratio (LR) of 11.31; at the cut-off of 16 AU/mL, they were 0.79 (CI 0.70-0.86) and 1.00, respectively (CI 0.92-1.00), with LR 4.50.

CONCLUSIONS

In patients younger than 2 years, suspected for CD, tTG is very valuable in selecting for small intestinal biopsy.

Celiac disease: diagnostic criteria in progress

Until a few years ago, celiac disease (CD) was thought to be a rare food intolerance that was confined to childhood and characterized by severe malabsorption and flat intestinal mucosa. Currently, CD is regarded as an autoimmune disorder that is common in the general population (affecting 1 in 100 individuals), with possible onset at any age and with many possible presentations. The identification of CD is challenging because it can begin not only with diarrhea and weight loss but also with atypical gastrointestinal (constipation and recurrent abdominal pain) and extra-intestinal symptoms (anemia, raised transaminases, osteoporosis, recurrent miscarriages, aphthous stomatitis and associated autoimmune disorders), or it could be completely symptomless. Over the last 20 years, the diagnostic accuracy of serology for CD has progressively increased with the development of highly reliable tests, such as the detection of IgA tissue transglutaminase and antiendomysial and IgG antideamidated gliadin peptide antibodies. The routine use of antibody markers has allowed researchers to discover a very high number of 'borderline' cases, characterized by positive serology and mild intestinal lesions or normal small intestine architecture, which can be classified as potential CD. Therefore, it is evident that the 'old celiac disease' with flat mucosa is only a part of the spectrum of CD. It is possible that serology could identify CD in its early stages, before the appearance of severe intestinal damage. In cases with a positive serology but with mild or absent intestinal lesions, the detection of HLA-DQ2 and HLA-DQ8 can help reinforce or exclude the diagnosis of gluten sensitivity.

Diagnosis and management of coeliac disease in children

Coeliac disease (CD) remains under diagnosed with only 10-20% of patients identified. Genes encoding HLA DQ2 or DQ8 are found in the vast majority of those with CD and testing for their presence can be useful to rule out the possibility CD. CD is more common in certain ethnic groups including those of North Indian origin. The classical presentation tends to occur in younger children, while atypical presentations occur at an older age. The number of children being diagnosed with CD is increasing; this may be due to greater recognition of the more atypical presentations, improved serologic tests, and the screening of asymptomatic groups at increased risk, but may also be due to an overall increased prevalence. Although serologic testing has become more reliable, there still remain significant problems around testing, particularly in those <18 months of age. All children should undergo a duodenal biopsy on a gluten containing diet in order to diagnose CD before recommending a gluten-free diet (GFD). A GFD should be offered to all children diagnosed with CD even when perceived as asymptomatic, as there is significant morbidity associated with CD later in life.

How do children experience participating in a coeliac disease screening? A qualitative study based on children’s written narratives

Aim: To explore how 12-year-old Swedish children experienced being involved in a coeliac disease (CD) screening. Methods: A qualitative approach was used to analyse short narratives written by children who had taken part in a school-based CD screening. Narratives were written after blood sampling, but prior to learning of the test results. Through an oscillation between the texts, codes, subcategories and four categories, a theme was generated describing the children’s experience. Results: The theme ‘‘A Journey towards Confidence’’ captures the overall experience of the screening. It illustrates that, although some children faced fear or anxiety, overall they had or were provided tools allowing them to cope well and experience a journey towards confidence. The categories describe conditions that contributed to the experience. The first, being involved, reflects the importance of involvement in receiving information and deciding to participate. Being a ‘‘good citizen’’ refers to feeling a duty to help and a trust to be treated fairly. Being able to cope with the screening was influenced by the children’s ability to manage sensations and support received. The last category, being able to balance risk, illustrates that the children were able to balance the risks of screening when they had a realistic understanding of the disease and their vulnerability and had tamed their anxiety. Conclusions: This study increases the understanding of how 12-year-old Swedish children experienced participating in a CD screening and describes conditions important for a positive experience. We show that, although some children faced anxiety, they had, or were provided with, tools allowing them to cope well and gain confidence.

Positive deamidated gliadin peptide antibodies and negative tissue transglutaminase IgA antibodies in a pediatric population: to biopsy or not to biopsy

Reports from our clinical laboratory database show that 75% of children <2 years old tested for celiac serology who were found positive for deamidated gliadin peptide (DGP) antibodies had negative results for tissue transglutaminase IgA. DGP levels were shown to decline and disappear without a gluten-free diet. This observation questions DGP's specificity for diagnosis of celiac disease.

Deamidated gliadin peptide antibodies as a routine test for celiac disease: a prospective analysis

GOALS

This study was designed to establish whether deamidated gliadin peptide antibodies (DGP-AGA) could improve the serologic workup for celiac disease (CD).

BACKGROUND

The best serologic approach for CD screening is currently based on the combined detection of tissue transglutaminase (tTGA), endomysial (EmA), and gliadin antibodies (AGA).

STUDY

One hundred forty-four consecutive patients with gastrointestinal and extraintestinal signs suggestive for CD were investigated using serologic tests, that is, IgG and IgA DGP-AGA, IgA tTGA, IgA EmA, and duodenal biopsy.

RESULTS

Forty-eight out of 144 patients (33%) had CD with different severity of villous atrophy. IgA tTGA showed 93.7% sensitivity compared with 91.6% for IgA EmA, 84.3% for IgA DGP-AGA, and 82.3% for IgG DGP-AGA. Of the 3 cases negative for IgA tTGA, IgA EmA, and IgA DGP-AGA, 2 had total IgA deficiency, although both were positive for IgG DGP-AGA. IgG DGP-AGA showed a very high specificity for CD (98.9%), not only superior to IgA DGP-AGA (79.8%), but also to IgA tTGA (96.6%) and very close to IgA EmA (100%).

CONCLUSIONS

Our prospective study shows that the combined search for IgA tTGA and IgG DGP-AGA provides the best diagnostic accuracy for CD, allowing the identification of all CD cases---except one---with a very high specificity. The serologic workup for CD screening could be significantly improved by the routine introduction of IgG DGP-AGA together with IgA tTGA, thus reducing the number of tests and with an obvious advantage in terms of cost-efficacy.

Old and new serological tests for celiac disease screening

Evaluation of: Lewis NR, Scott BB. Meta-analysis: deamidated gliadin peptide (DGP) antibody and tissue transglutaminase (tTG) antibody compared as screening test for celiac disease. Aliment. Pharmacol. Ther. 31(1), 73-81 (2010). In celiac disease (CD), deamidation of gliadin peptides, induced by tissue transglutaminase (tTG), generates novel antigenic epitopes evoking a specific immune response. Serological tests based on the detection of antibodies to deamidated gliadin peptides (DGP) have been developed with very promising results in terms of sensitivity and specificity for CD screening. In the present study, a meta-analysis of studies published from 1998 to 2008 was designed to compare the performance of DGP antibodies with that of tTG antibodies, the validated and routinely employed test for CD screening. The authors have limited their analysis to IgA class antibodies underlining that most of the considered studies had methodological imperfections, especially ascertainment bias. The results of this meta-analysis indicated that the pooled sensitivities for DGP and tTG antibodies were 87.8% (95% CI: 85.6-89.9) and 93% (95% CI: 91.2-94.5), respectively, and the pooled specificities were 94.1% (95%CI: 92.5-95.5) and 96.5% (95% CI: 95.2-97.5), respectively. In summary, although both tests represent a very good tool for identifying celiac patients, tTG antibodies display a higher predictive value than DGP antibodies, and must still be considered the best serological test for CD screening.

Serum and intestinal celiac disease-associated antibodies in children with celiac disease younger than 2 years of age

OBJECTIVES

In children younger than 2 years of age, a diagnosis of celiac disease (CD) is difficult to make because anti-endomysium (anti-EMA)/anti-tissue transglutaminase 2 (anti-TG2) antibodies are less sensitive than in older children. The aim of our study was to evaluate how many children younger than 2 years of age and diagnosed with CD, were negative for serum anti-TG2 antibodies and to test the hypothesis that in these patients, TG2-specific IgA deposits could instead be present at mucosal level.

PATIENTS AND METHODS

A total of 104 children younger than 2 years of age and 179 children older than 2 years, all of whom had been diagnosed with CD, were investigated for serum CD-associated antibodies (anti-gliadin [AGA] IgA and IgG, EMA-IgA, anti-TG2-IgA). The presence of intestinal anti-TG2 extracellular IgA deposits was searched by using double immunofluorescence in 56 of the patients younger than 2 years of age and in 40 of those who were older than 2 years.

RESULTS

In children with CD who were younger than 2 years of age, high levels of AGA-IgA were found in 93/104 (89%) and 98/104 (94%) were found of have high levels of AGA-IgG. In children older than the age of 2 years with CD, 120/179 (67%) had high levels of AGA-IgA and 151/179 (84%) had high levels of AGA-IgG. Serum EMA were present in 92/104 (88%) in the younger group and in 176/179 (98%) of the older group. Ninety-one of 104 children (87%) younger and 172/179 (96%) older than 2 years showed high serum levels of anti-TG2. Finally, 41/56 (73%) children younger than 2 years and all of the 40 children (100%) older than 2 years of age showed mucosal anti-TG2-IgA deposits.

CONCLUSIONS

EMA and anti-TG2-antibody measurements show higher sensitivity for the diagnosis of CD in children older than 2 years compared with younger children. The search for mucosal deposits of anti-TG2-IgA does not improve the diagnostic performance.

Serologic screening for celiac disease in children: a comparison between established assays and tests with deamidated gliadin-derived peptides plus conjugates for both IgA and IgG antibodies

Selection of patients for diagnostic biopsy concerning celiac disease (CD) is mainly guided by the results with serological screening tests like anti-tissue-transglutaminase (tTG), anti-endomysium (EmA) and anti-gliadin (AGA) IgA. New tests using deamidated gliadin-derived peptides (DGP) including both IgA and IgG antibodies have been developed, to cover the IgA-deficient sera. In addition, a combined IgA and IgG DGP test, with or without human erythrocyte-derived tTG, offers possible advantages. In order to explore the screening accuracy of the new combination tests sera from 167 children below 3 years of age were assayed. Biopsy had been taken in connection with serology in 32 of these children, 24 with histopathological CD. The results with the DGP and the combined test were congruent with the IgA antibody tests for tTG, EmA and AGA, all identifying 21 of 24 of the CD cases. Two of the CD patients were AGA-IgA positive only (2/24), while 2 of 24 sera were AGA-IgA negative but positive in all the other tests. These results raises the question whether the modifications of the gliadin antigen not only decrease false positivity but also give more false-negative results, a major drawback for a screening test for an important disease. Further studies have to be undertaken to explore this. Our results also stress that serologic screening of CD in children cannot be based on one test only.

New developments in serodiagnosis of childhood celiac disease: assay of antibodies against deamidated gliadin

Antibodies to deamidated gliadin present a new tool in the diagnosis of celiac disease (CD). In children, the ELISA for the determination of IgG antibodies to (deamidated) gliadin-analogous fusion peptides (GAF3X) has a superior performance compared to the ELISA for the determination of antibodies against native gliadin and is comparable to assays for IgA antibodies against tissue transglutaminase (IgA-anti-tTG). The combined investigation of IgG antibodies to GAF3X (IgG-anti-GAF3X) and IgA-anti-tTG significantly increases the fraction of children definitely identified as either CD or non-CD patients. The new IgG-anti-GAF3X ELISA was also able to detect CD in three cases of IgA deficiency and in two cases of latent CD and was also useful in the diagnosis of children younger than 2 years of age.

Pediatric celiac disease

PURPOSE OF REVIEW

Celiac disease is an extremely common, although underdiagnosed, disorder. Knowledge about the varied clinical manifestations and the proper approach to screening and diagnosing celiac disease will lead to appropriate early intervention in affected children

RECENT FINDINGS

New age-dependent algorithms are emerging to properly screen for celiac disease. There is new evidence on the patchy nature of celiac disease supporting the practice of multiple duodenal biopsies including the bulb of the duodenum. Therapeutic dietary compliance, particularly in asymptomatic children, can be poor, and therefore, the involvement of a dietician trained in celiac disease is instrumental in keeping patients up to date with dietary guidelines and to improve their compliance to the diet. Expanding knowledge about the pathogenesis of celiac disease has led to the development of investigational therapeutic alternatives to the gluten-free diet. Ongoing clinical trials are evaluating methods of celiac disease prevention in at-risk infants.

SUMMARY

This review aims at outlining the different manifestations of celiac disease in children as well as a step-wise approach to screen and diagnose the disease. A better understanding of the pathogenic mechanisms of celiac disease is paving the way to innovative diagnostic tools, preventive strategies, and therapeutic interventions alternative to a gluten-free diet.