Finn E Somnier1, Peter J H Engel. 1. Laboratory of Neuroimmunology, Department of Neurology, The National Hospital (Rigshospitalet), Copenhagen, Denmark. Somnier@dadlnet.dk
Abstract
OBJECTIVE: To estimate the incidence of elevated anti-titin antibodies titers and of thymomas in a population of patients with MG using various statistics and associations. METHODS: Extensive epidemiology, systematic measurement of anti-titin antibodies, and histologic assessment of thymomas according to the new World Health Organization classification. RESULTS: The mean annual incidence rate of MG per million population was 8.3. The analogous mean rate of thymomas was 2.0, out of which MG was encountered in about 20%. A thymoma was coexistent in 7% of the patients with MG. The finding of titin autoantibodies and the coexistence of thymomas were both associated with age at the appearance of MG. In patients with MG with a thymoma, the frequency of seropositivity was 68%, whereas acetylcholine receptor (AChR) autoantibodies were detected in all such sera. Titin autoantibody-positive sera were also anti-AChR antibodies positive. Further, all serum samples negative for anti-AChR antibodies were devoid of anti-titin antibodies. Titin autoantibodies were not detected in nonthymoma early-onset MG. CONCLUSION: Apart from MG with a thymoma, the finding of the titin autoantibodies was observed to be an exclusive feature of late-onset MG, the frequency being 55%. No data were found to suggest that patients with MG were more likely to present with thymic tumors than other patients exhibiting thymic neoplasia. In about 80%, such tumors in MG were composed of cortical cells. The concept of the anti-titin antibodies merely as a paraneoplastic marker in MG was not supported by these data.
OBJECTIVE: To estimate the incidence of elevated anti-titin antibodies titers and of thymomas in a population of patients with MG using various statistics and associations. METHODS: Extensive epidemiology, systematic measurement of anti-titin antibodies, and histologic assessment of thymomas according to the new World Health Organization classification. RESULTS: The mean annual incidence rate of MG per million population was 8.3. The analogous mean rate of thymomas was 2.0, out of which MG was encountered in about 20%. A thymoma was coexistent in 7% of the patients with MG. The finding of titin autoantibodies and the coexistence of thymomas were both associated with age at the appearance of MG. In patients with MG with a thymoma, the frequency of seropositivity was 68%, whereas acetylcholine receptor (AChR) autoantibodies were detected in all such sera. Titin autoantibody-positive sera were also anti-AChR antibodies positive. Further, all serum samples negative for anti-AChR antibodies were devoid of anti-titin antibodies. Titin autoantibodies were not detected in nonthymoma early-onset MG. CONCLUSION: Apart from MG with a thymoma, the finding of the titin autoantibodies was observed to be an exclusive feature of late-onset MG, the frequency being 55%. No data were found to suggest that patients with MG were more likely to present with thymic tumors than other patients exhibiting thymic neoplasia. In about 80%, such tumors in MG were composed of cortical cells. The concept of the anti-titin antibodies merely as a paraneoplastic marker in MG was not supported by these data.
Authors: Isabell Cordts; Nicolas Bodart; Kathi Hartmann; Katerina Karagiorgou; John S Tzartos; Lin Mei; Jens Reimann; Philip Van Damme; Michael H Rivner; Alain Vigneron; Joachim Weis; Jörg B Schulz; Socrates J Tzartos; Kristl G Claeys Journal: J Neurol Date: 2017-05-17 Impact factor: 4.849