The Tissue Transglutaminase IgG Antibody test is a blood test used to aid in the diagnosis of celiac disease, an autoimmune disorder characterized by an intolerance to gluten. Transglutaminase is an enzyme that is involved in the cross-linking of proteins, and tissue transglutaminase is an enzyme that is primarily found in the small intestine. In celiac disease, the body’s immune system mistakenly attacks tissue transglutaminase, resulting in damage to the lining of the small intestine. This test measures the level of antibodies produced by the body against tissue transglutaminase. Elevated levels of these antibodies suggest the presence of celiac disease. The test is considered to be highly specific and sensitive, making it a valuable tool in the diagnosis and management of celiac disease.