Cortes-Vicente E, Gallardo E, Martinez M, et al. Clinical Characteristics of Patients with Double-Seronegative Myasthenia Gravis and Antibodies to Cortactin. JAMA Neurol 2016;73:1099-1104.
Submitted by Rocio (Carolina) Garcia, MD, News Science Editorial Board
The objective of this restrospective cohort study of patients with myasthenia gravis was to determine the characteristics of patients negative for both acetylcholine receptor antibodies (AchR Ab) and MuSK antibodies and positive for cortactin antibodies and compare them with seropositive patients. A total of 250 patients were included; 80% (201) were AchR-Ab positive, 4.4% (11) were MUSK-Ab positive and 15.2% (38) were double seronegative. Nine out of the 38 double seronegative patients were positive for cortactin antibodies. These patients tended to be younger than those with AChR Ab myasthenia gravis and had milder disease: none of the cortactin positive patients had bulbar symptoms, six had pure ocular symptoms, and three had mildly generalized myasthenia gravis.
Cortactin is a post synaptic neuromuscular junction protein involved in acetylcholine receptor clustering. Though not yet proven to be pathogenic, antibodies to cortactin can be added to the list of antibodies described in patients with double seronegative myasthenia gravis LRP4, agrin, and Dok-7 subgroup. The milder disease phenotype in patients with cortactin antibodies needs to be confirmed in larger samples.
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