Celiac disease (CD) is a common auto-immune disorder induced by gluten ingestion in genetically susceptible individuals (HLA-DQ2/DQ8). Gluten induces small-bowel villous atrophy and a specific immune response characterized by the production of CD-autoantibodies against transglutaminase 2 (anti-TG2) and endomysium (EMA). In symptomatic patients with positive-serum antibodies and villous atrophy, the diagnosis of CD is clearcut.

However, 10-30% of patients evaluated for suspected CD show only mild histopathologic changes and fluctuating serologic markers, a condition identified as potential CD. In such cases the diagnosis may remain uncertain.

CD-autoantibodies are produced by intestinal B-cells in the early phases of the disease, before their appearance in the serum and when the duodenal mucosa is still normal. Intestinal CD-antibodies (I-CD-abs) are a marker of CD, have a high sensitivity and specificity for CD and identify those patients with potential CD who are at risk of progression to villous atrophy. I-CD-abs can be detected by double immunofluorescence staining on frozen duodenal sections or by using an endomysial antibody assay in the culture medium of duodenal biopsies (EMAbiopsy).

The diagnostic accuracy of these techniques is comparable as they both have high sensitivity and specificity. However, their implementation in clinical practice is limited because they require both experienced operators and well-equipped laboratories. There is an unmet need: the development of a new simple and effective diagnostic tool that any gastroenterology unit can use in routine diagnostics to ensure a prompt diagnosis in suspected CD patients, who may benefit from a therapy based on gluten-free diet, and to reduce both unnecessary medical investigations and diagnostic delays.

In order to simplify and shorten times for the detection of these intestinal antibodies, the study aims to substitute the EMAbiopsy assay with a supernatant obtained quickly after mechanical lysis of fresh intestinal biopsy specimen. The obtained samples will be tested with rapid (about 15 minutes) immune-chromatographic anti-TG2 assay (Rapid Intestinal anti-TG2 Assay).

Inclusion Criteria:

- Patients undergoing an elective esophagogastroduodenoscopy (EGD) for suspected Celiac Disease (CD), eosinophilic esophagitis, autoimmune enteropathy, inflammatory bowel disease, gastritis, gastric or duodenal ulcer, gastroesophageal reflux disease.

Exclusion Criteria:

• Bleeding disorders
• Patients fulfilling the new European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) guidelines for diagnosing CD (version 2020) for a serology-based CD diagnosis
• Subjects in whom intestinal biopsies are not indicated as part of the diagnostic process

Children (aged between 2 and 17 years) referred to the Gastroenterology Units for elective gastro-intestinal endoscopy.