(1) To assess the predictive value of anti‐tissue transglutaminase immunoglobulin A (IgA) antibodies (a‐tTG) by chemiluminescence immunoassay (CLIA) related to duodenal histology in children with suspected celiac disease (CD) and (2) to determine the cut‐off value of a‐tTG by CLIA that allows diagnosis of CD avoiding biopsy. This evidence concerns the gene CD79A and Cowden disease.