Diagnostic Accuracy of Tissue Transglutaminase and Combined Assay of Tissue Transglutaminase and Deamidated Gliadin Peptide in Children with Coeliac Disease: A Cross-sectional Study

Introduction: Coeliac Disease (CD) is a systemic immune disorder caused by gluten in genetically susceptible individuals. A serological screening assay for CD has been designed to detect Immunoglobulin A (IgA) and IgG anti-tissue Transglutaminase (a-tTG) and IgA and IgG Deamidated Gliadin Peptide antibodies (a-DGP) simultaneously. The seronegative gap can be closed when these two antigens are combined on a single solid phase. This is primarily because untreated CD children who are negative for antibodies of one of the antigens may exhibit a positive result for the other. Aim: To determine the diagnostic parameters {sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV)} of tTG-IgA and htTG-DGP (Coeliac fusion- a combination of IgA and IgG to human tTG and synthetic DGP) for the diagnosis of CD in clinically symptomatic children. Materials and Methods: This cross-sectional study was conducted at the Paediatric Outpatient Department (OPD) of Santokhba Durlabhji Memorial Hospital, Jaipur, Rajasthan, India from April 2023 to November 2023. The study population comprised 45 children (age >6 months and