IgA-class autoantibodies against neuronal transglutaminase, TG6 in celiac disease: No evidence for gluten dependency

Background It has been suggested that antibodies against transglutaminase (TG) 6 could serve as a biomarker to identify a subgroup of gluten-sensitive patients who may be at risk of developing neurological disease. We here investigated whether TG6-targeted autoantibodies are a characteristic feature of celiac patients, especially those with neurological symptoms, and further, whether such antibodies are gluten-dependent. Methods Serum IgA-class TG6 autoantibodies were measured in untreated and treated celiac patients with and without neurological manifestions and in non-celiac controls. The results were compared to TG2 autoantibody levels. Results During a gluten-containing diet the number of TG6 autoantibody-positive celiac patients with neurological problems (25%) did not significantly differ from that of TG6-seropositive patients without neurological impairment (16%) or from non-celiac controls (15%). This was in contrast to our finding in TG2 autoantibody-positive individuals, whose numbers differed significantly between all three study groups. On a gluten-free diet the levels of TG6 autoantibodies remained unchanged. Conclusions We conclude that the serum IgA-class TG6 autoantibody assay is not able to distinguish gluten-sensitive patients with neurological manifestations from celiac patients without neurological problems or from control subjects, and further, that TG6 autoantibodies are not gluten-dependent.