Celiac disease is associated with a variety of autoantibodies, including endomysial, tissue transglutaminase (tTG), and deamidated gliadin antibodies. Although the IgA isotype of these antibodies usually predominates in celiac disease, individuals may also produce IgG isotypes, particularly if the individual is IgA deficient. The most sensitive and specific serologic tests are tTG and deamidated gliadin antibodies. The disease is HLA-associated (>95% of patients have DQ2 & DQ8 HLA marker) and manifests at any age with a peak onset in early childhood, even in neonates. The determination of IgG antibodies to tTG is the only available specific serology for those 2% to 5% of patients with IgA deficiency.