This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
Most specific antibody for celiac disease in patients with IgA deficiency 
Select and explain. 
A. Anti - endomyseal, B. Anti - tissue transglutaminase, C. Anti - reticulin, D. Anti - Gliadin
D: Anti - Gliadin
Answer: D: Anti - Gliadin 
Explanation: Most specific - Anti - TTG
Most specific in IGA deficiency - Anti - Gliadin.