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.
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.