This study aims to retrospectively characterize a cohort of children with seronegative myasthenia gravis, compared to those with seropositive disease.           

We analyzed patients’ symptoms, co-existing diagnoses, exam findings, results of antibody and electrodiagnostic findings , and response to treatments among a cohort of 35 children with myasthenia gravis over 7 years, and compared seronegative to seropositive patients. 

We identify several distinct phenotypes among seronegative patients. These include children with autoinflammatory disorders, children with pain-associated myasthenia, those with a slow channel syndrome-like phenotype, and ocular myasthenia. Several children in the seronegative group required ICU care and plasma exchange, underscoring the severity of seronegative MG.  Furthermore, some seronegative children without characteristic 10% decremental response on repetitive nerve stimulation showed severe symptoms and a robust response to immunotherapies, including IVIg, plasma exchange and rituximab.

Children with seronegative myasthenia manifest with diverse phenotypes, and sometimes lack characteristic findings on repetitive nerve stimulation, making diagnosis more challenging. Nonetheless, they can suffer from severe disease and may respond well to immunotherapy, highlighting the need to correctly diagnose children with MG early in their disease course.