Can Testing for Antibodies to Deamidated Gliadin Peptide Allow Earlier Celiac Disease Diagnosis in Children?

Celiac.com 01/29/2015 - Testing for tissue transglutaminase antibodies (TGA) is currently a common part of attempting to diagnose celiac disease. A research team wanted to find out if determination of antibodies to synthetic deamidatedgliadin peptides (anti-DGP) might work as an alternative or complement to TGA testing.

To find out, the team assessed the performance of a time-resolved immunofluorometry (TR-IFMA) based anti-DGP assay in the diagnosis of celiac disease in children, and also retrospectively analyzed the appearance of anti-DGP antibodies before TGA seroconversion. The research team included A. Lammi, P. Arikoski, S. Simell, T. Kinnunen, V. Simell, S. Paavanen-Huhtala, A. Hinkkanen, R. Veijola, M. Knip, J. Toppari, O. Vaarala, O. Simell, and J. Ilonen.

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They are variously affiliated with the Department of Clinical Microbiology and the A.I. Virtanen Institute for Molecular Sciences at the University of Eastern Finland in Kuopio, Finland, the Department of Pediatrics at Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland, the Department of Pediatrics at the University of Oulu and Oulu University Hospital in Oulu, Finland, the Children's Hospital, and the Institute of Clinical Medicine at the University of Helsinki in Helsinki, Finland, the Folkhälsan Research Center in Helsinki, Finland, the Department of Pediatrics at Tampere University Hospital in Tampere, Finland, the Immunogenetics Laboratory, and the Department of Physiology at the University of Turku, and with the Department of Pediatrics and Adolescent Medicine at the University of Turku and Turku University Hospital in Turku, Finland.

For their study, the team assessed 92 children with biopsy-confirmed celiac disease. The team took blood samples at the time of, or just prior to, clinical diagnosis. The team also assessed a control group of 82 TGA-negative children who were positive for HLA-DQ2 or -DQ8.

Based on receiver operating characteristics (ROC) curves, they found that the optimal cut-off value for IgA anti-DGP positivity was 153 arbitrary units (AU) with a sensitivity of 92.4% and specificity of 97.6%, while the optimal cut-off value for IgG anti-DGP 119 AU, with a sensitivity of 97.8% and specificity of 97.6%.

They found that all 92 children with celiac disease tested positive for either IgA or IgG anti-DGP at the time of diagnosis.

Blood results from 48 children with celiac disease, analyzed retrospectively before the diagnosis, showed that anti-DGP antibodies preceded TGA positivity in 35 of 48 celiac disease children and appeared an average of one year earlier.

From these results, the TR-IFMA test for detecting anti-DGP antibodies shows high sensitivity and specificity for celiac disease in children. For most of the patients, anti-DGP seropositivity preceded TGA positivity, which means that monitoring anti-DGP antibodies frequently in genetically susceptible children might allow doctors to spot celiac disease earlier than allowed by current tests.

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