In summary, subacute onset of myoclonus in combination with signs of encephalopathy, seizures, brainstem involvement, autonomic features and recent prominent sleep disorder should alert the clinician for an autoimmune condition, and testing in particular for CASPR2, LGI1, DPPX, IgLON5 and GlyR antibodies should be considered. The gene discussed is CNTNAP2; the disease is Myoclonus.