The anti-smooth muscle antibody (ASMA) test is an immunoseriopathological test that detects the presence of autoantibodies, primarily IgG, directed against components of the smooth muscle cytoskeleton, particularly actin. It is typically performed using immunosorbent assay (IFA) on tissue slides containing smooth muscle (such as gastric or esophageal tissue). The presence of these antibodies, especially at elevated titers, is strongly associated with the preliminary diagnosis of autoimmune hepatitis type 1 (AIH type 1).