Coeliac disease in infants: antibodies to deamidated gliadin peptide come first!

Usefulness of deamidated gliadin peptide antibodies in diagnosing coeliac disease in children younger than 3 years old

AIM

The standard serological test to screen for coeliac disease (CD) is tissue transglutaminase (tTG) but some experts recommend including deamidated gliadin peptide (DGP) antibodies for children younger than 3 years old. This study evaluated the utility of DGP-immunoglobulin A (IgA) and DGP-immunoglobulin G (IgG) serologies when screening children younger than 3 years old for CD.

METHODS

A retrospective chart review was conducted including children 3 years old and under, who had DGP and/or tTG serologies along with duodenal biopsies during their initial diagnostic evaluation. Serology results were compared to the gold-standard histopathology by χ² to determine the significance of including DGP-IgG/IgA serologies when screening for CD in this age group.

RESULTS

We identified 478 patients, 52 who were younger than 3 years old, 43 of whom met inclusion criteria. The positive predictive value (PPV) of the DGP-IgA test was 91.7% whereas, DGP-IgG was 77.8%. When DGP serology was examined in conjunction with tTG-IgA, the PPV with DGP-IgA was 90.9% and with DGP-IgG was 87.5%.

CONCLUSIONS

In isolation, DGP-IgA provides a high PPV and specificity for CD in children younger than 3 years old, whereas DGP-IgG had a much lower PPV in this age group. When used alone or in conjunction with tTG-IgA, the DGP-IgA test results in a high PPV of 91.7 and 90.9%, respectively. Based on our study, we recommend obtaining both the DGP-IgA and the tTG-IgA serology when screening infants and children younger than 3 years old for coeliac disease.

Evaluation of Celiac Disease by Minimally Invasive Biomarkers in a Spanish Pediatric Population

Background: The diagnosis of celiac disease (CD) has been substantially improved with the availability of highly sensitive CD-specific IgA-TG2, Ig-GDP, and IgA-EMA. The European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) published (2012) and updated (2020) diagnostic criteria for CD in order to simplify CD diagnosis and to avoid biopsies in selected patients. Methods: A prospective study including 5641 pediatric patients (0–16 years old) from January 2012 to January 2019 was performed. CD diagnosis was made according to the ESPGHAN algorithm. The objective of this study was to evaluate the utility of biomarkers and the relationship between TGA-IgA and EMA titers. Results: CD diagnoses were confirmed in 113 patients, 110 were IgA-TG2-positive and 3 (2.7%) had IgA deficiency. The diagnosis was made by serologic tests in 95 (84.1%) patients. Only 18 (15.9%) patients underwent intestinal biopsy. We obtained 100% concordance between IgA-EMA and positive results for IgA-TG2 ≥ 10 ULN with IgA-EMA antibody titer ≥ 1:80. Conclusions: This study provides evidence of a positive correlation between IgA-TG2 antibody serum levels and IgA-EMA. The diagnosis could be guaranteed with strict application of IgA-TG2 values ≥ 10 ULN (confirmed by subsequent testing) plus the serological response to the gluten-free diet (GFD).

Diagnostic Accuracy of IgA Anti-Transglutaminase and IgG Anti-Deamidated Gliadin for Diagnosis of Celiac Disease in Children under Two Years of Age: A Systematic Review and Meta-Analysis

The need of adding the determination of anti-deamidated gliadin peptide (DGP) IgG to anti-transglutaminase (TTG) IgA antibodies for diagnosis of celiac disease (CD) in children <2 years of age is controversial. We performed a systematic review and meta-analysis to evaluate, by head-to-head comparison, the diagnostic accuracy of TTG IgA and DGP IgG antibodies. We searched PubMed, MEDLINE, and Embase databases up to January 2021. The diagnostic reference was intestinal biopsy. We calculated the sensitivity and specificity of these tests and the odds ratio (OR) between the tests. Fifteen articles were eligible for the systematic review and ten were eligible for the meta-analysis. Sensitivity and specificity were 0.96 (95% confidence interval (CI), 0.91–0.98) and 0.96 (95% CI, 0.85–0.99) for DGP IgG and 0.93 (95% CI, 0.88–0.97) and 0.98 (95% CI, 0.96–0.99) for TTG IgA, respectively. TTG IgA specificity was significantly higher (OR 9.3 (95% CI, 2.3–37.49); p < 0.001) while the sensitivity of DGP IgG was higher without reaching statistical significance (OR: 0.6 (95% CI, 0.24–1.51); p = 0.28). Both the meta-analysis and the systematic review showed that some children with early CD are missed without the DGP IgG test. In children <2 years of age, TTG IgA is the best CD screening test; however, the addition of DGP IgG may increase the diagnostic sensitivity.

Influence of Age and Type 1 Diabetes Mellitus on Serological Test for Celiac Disease in Children

PURPOSE

Serological tests of tissue transglutaminase (TTG) and deamidated gliadin (DGP) antibodies for celiac disease diagnosis show conflicting correlation with histology in young children and in type 1 diabetes mellitus (T1DM). Tests' ability to predict histology and cutoff values based on age and T1DM was evaluated.

METHODS

A retrospective study of children who had celiac serological tests between 6/1/2002 and 12/31/2014 at a pediatric hospital.

RESULTS

TTG IgA displayed similar results in predicting histology between <4.0 and ≥4.0 years age groups with sensitivity 98% and 93%, and specificity 88% and 86%, respectively. In children <4.0 years old, sensitivity for DGP antibodies was 100% and specificity 94%; in ≥4.0 years age groups, sensitivity was 60%, 88% for DGP IgA and IgG and specificity 95%, 96%, respectively. TTG IgA had low specificity in patients with T1DM compared with non-T1DM, 42% vs. 91%. Positive TTG IgA with normal histology was associated with higher T1DM prevalence at 36% compared with negative tests at 4%. Finally, the TTG IgA cutoff value was higher in T1DM at 36 vs. 16.3 units in non-T1DM. DGP IgG cutoff showed similar values between age groups; TTG IgA and DGP IgA cutoffs were lower in <4.0 years at 8.3 and 11.9 units than ≥4.0 years at 23.4 and 19.9, respectively.

CONCLUSION

TTG IgA is sufficient for the <4.0 years age group and DGP antibodies had no advantage over TTG IgA in older children. The cutoff value to determine a positive TTG IgA should be higher for children with T1DM.