Focal seizures in a patient with myotonic disorder type 2 co-segregating with a chloride voltage-gated channel 1 gene mutation: a case report

BACKGROUND: Myotonic dystrophy type 2 is a multisystem disorder with both neurological and non-neurological signs and symptoms. Seizures are not a commonly associated neurological feature of this disorder. CASE PRESENTATION: A 57-year-old white American man presented with a long history of clinical and electrophysiological features of a myotonic disorder. He also developed multiple episodes of focal seizures and underwent a series of investigations which showed no structural or metabolic etiology. Genetic testing revealed that he had an expansion mutation in CCHC-type zinc finger, nucleic acid binding protein gene confirming the diagnosis of myotonic disorder type 2 and carried a mutation in the chloride voltage-gated channel 1 gene. CONCLUSIONS: We report a rare association between myotonic dystrophy type 2 and a seizure disorder. The pathophysiology of a possible relationship between these two neurological conditions is discussed.