Anti-titin antibodies in a cohort of myasthenia gravis patients.

Background:Anti-titin antibodies have been previously associated with thymoma-associated myasthenia gravis (MG) and a more clinically severe form of MG. While currently only serving as a disease biomarker, its possible utility as an indicator of underlying thymus malignancy may be of value in clinical practice. Methods:Data was retrospectively collected and analyzed from 2013 to 2022 using an institutional record of MG patients. Anti-titin antibodies were assessed using Line Blot immunoassay. Results:From 130 MG cases, 32 (24.6%) were anti-titin positive. Anti-titin positive cases were associated with older age of disease onset [median (IQR): 63.0 (44.3-70.8) vs. 35.5 (24.8-60.8) years] (P<0.01). Thymectomy was performed in 46 (35.4%) MG patients, 12 of which anti-titin positive (26.1%). Thymectomy samples from anti-titin positive patients comprised 10 (83.3%) cases of thymoma and 2 (16.7%) cases of thymus hyperplasia. There was a tendency towards anti-titin positive patients having more thymoma while anti-titin negative displayed more hyperplasia (P<0.01). Anti-titin positivity correlated with thymoma in patients with age of onset bellow 50 years (P=0.028). Anti-titin positivity was significantly associated with generalized MG in the late-onset group (P=0.005). Conclusions:The presence of anti-titin antibodies appears to correlate with underlying thymoma in early-onset MG cases and with generalized MG in late-onset cases. Prospective studies are needed to further study this association.