This retrospective cross-sectional study describes the frequency and clinical features of patients with double-seronegative myasthenia gravis (dSNMG) who have cortactin antibodies. Cortactin plays a critical role in the development of the neuromuscular jusntion. The authors investigated serum samples from 38 patients with clinically and electrophysiologically defined MG who were negative for AChR and MuSK antibodies. Nine of these patients had antibodies directed toward cortactin, and these patients had ocular or mild generalised MG. Among the 17 patients with ocular MG in the dSNMG group, 4 (23.5%) had antibodies to cortactin. A few other individuals had antibodies to both AChR and cortactin. Including the detection of cortactin antibodies in the routine diagnosis of dSNMG may be helpful in ocular MG.
