Deamidated Gliadin Antibodies: Do They Add to Tissue Transglutaminase-IgA Assay in Screening for Celiac Disease?

Diagnostic performances of celiac disease serological tests among Saudi patients

BACKGROUND

: The prevalence of celiac disease (CD) is relatively high in Saudi Arabia, and little is known about the accuracy of serological markers in the local population. This study aimed to assess the diagnostic performance of various serological markers for detecting CD in Saudi children and adults.

METHODS

We conducted a retrospective study of 148 CD patients and 512 controls to assess the diagnostic performances of IgA anti-tissue transglutaminase antibodies (TTG), IgG anti-TTG, IgA anti-deamidated gliadin peptide antibodies (anti-DGP), IgG anti-DGP, and endomysium antibodies (EMA).

RESULTS

: Immunoglobulin A (IgA) anti-TTG was the most sensitive test [98.9% (95% confidence interval (CI) 94.1-99.8%)], while EMA was the most specific [100%, 95%CI 98.6-100%]. By applying the criteria of IgA anti-TTG titers ≥10 × upper limit of normal (ULN) and positive EMA, 57.3% of patients could have avoided intestinal biopsy. IgG anti-DGP test had a sensitivity of 85.9% (95% CI = 77.3-91.5%) and a specificity of 93.5% (95% CI = (90.0-95.9%). Titers of IgA anti-TTG, IgA anti-DGP, and IgG anti-DGP were higher in CD patients with the Marsh 3c class than in those with the Marsh 3b and Marsh 3a classes. IgG anti-TTG and IgA anti-DGP had no additional diagnostic value.

CONCLUSIONS

: IgA anti-TTG and EMA are excellent CD markers in children and adults. The use of IgA anti-TTG titers ≥10 × ULN and positive EMA as criteria for CD diagnosis in children and adults might be a good alternative to intestinal biopsy.

Diagnostic Value of Immunoglobulin G Anti-Deamidated Gliadin Peptide Antibody for Diagnosis of Pediatric Celiac Disease: A Study from Shiraz, Iran

PURPOSE

Screening serologic tests are important tools for the diagnosis of celiac disease (CD). Immunoglobulin (Ig)G anti-deamidated gliadin peptide (anti-DGP) is a relatively new autoantibody thought to have good diagnostic accuracy, comparable to that of anti-tissue transglutaminase (anti-tTG) antibody.

METHODS

Pediatric patients (n=86) with a clinical suspicion of CD were included. Duodenal biopsy, anti-tTG, and IgG anti-DGP antibody tests were performed. The patients were divided into CD and control groups based on the pathological evaluation of duodenal biopsies. The diagnostic accuracy of serological tests was determined.

RESULTS

IgA anti-tTG and IgG anti-DGP antibodies were positive in 86.3% and 95.4% of patients, respectively. The sensitivity, specificity, and diagnostic accuracy of the IgA anti-tTG test were 86.3%, 50.0%, and 68.6%, respectively, and those of the IgG anti-DGP test were 95.4%, 85.7%, and 90.7%, respectively. The area under the receiver operating characteristic (ROC) curve was 0.84 (95% confidence interval [CI], 0.74-0.91) for IgA anti-tTG test and 0.93 (95% CI, 0.86-0.97) for IgG anti-DGP test. The comparison of IgA anti-tTG and IgG anti-DGP ROC curves showed a higher sensitivity and specificity of the IgG anti-DGP test.

CONCLUSION

IgG anti-DGP is a reliable serological test for CD diagnosis in children. High tTG and DGP titers in the serum are suggestive of severe duodenal atrophy. The combined use of IgA anti-tTG and IgG anti-DGP tests for the initial screening of CD can improve diagnostic sensitivity.

The global burden of coeliac disease: opportunities and challenges

Coeliac disease is a systemic disorder characterized by immune-mediated enteropathy, which is caused by gluten ingestion in genetically susceptible individuals. The clinical presentation of coeliac disease is highly variable and ranges from malabsorption through solely extra-intestinal manifestations to asymptomatic. As a result, the majority of patients with coeliac disease remain undiagnosed, misdiagnosed or experience a substantial delay in diagnosis. Coeliac disease is diagnosed by a combination of serological findings of disease-related antibodies and histological evidence of villous abnormalities in duodenal biopsy samples. However, variability in histological grading and in the diagnostic performance of some commercially available serological tests remains unacceptably high and confirmatory assays are not readily available in many parts of the world. Currently, the only effective treatment for coeliac disease is a lifelong, strict, gluten-free diet. However, many barriers impede patients' adherence to this diet, including lack of widespread availability, high cost, cross-contamination and its overall restrictive nature. Routine follow-up is necessary to ensure adherence to a gluten-free diet but considerable variation is evident in follow-up protocols and the optimal disease management strategy is not clear. However, these challenges in the diagnosis and management of coeliac disease suggest opportunities for future research.