CD79A and selective IgA deficiency disease: The diagnosis of the patient was established through a combination of serological testing and endoscopic biopsy findings, consistent with the World Gastroenterology Organization guidelines for CD.[20] The initial negative anti-tissue transglutaminase IgA result highlights the need for comprehensive serological evaluation, including anti-deamidated gliadin peptide IgA, especially in cases of IgA deficiency or atypical presentations.