A common thread, relating to CNS expression of both proteins, may be cerebellar involvement: CASPR2 antibodies have been detected in as many as 10% of patients with ‘idiopathic ataxia’,29 while cerebellar features have been identified in 8% of patients harbouring LGI1 antibodies.4 Chorea is also an unusual association of both antibodies and has a wide differential diagnosis within autoimmune neurology,30 but other movement disorders are more divergent between the two antigenic targets. Here, CNTNAP2 is linked to movement disorder.