Testing for autoantibodies against the voltage-gated potassium channel receptor complex-associated proteins (CASPR2) is used in the investigation of patients with autoimmune encephalitis and Morvan's syndrome.
The CASPR2 protein (Contactin Associated Protein-2) is a voltage-gated potassium channel complex (VGKC) subunit and is part of the extracellular antigen group. Antibodies against the CASPR2 antigen may occur in neuromyotonia, autoimmune encephalitis, and Morvan's syndrome. There are relatively few published cases where 85% were men and the age of diagnosis was 46-77 years (mean 60 years). There is an association with malignancy, mainly thymoma. The CASPR2 antibody titer can be used to monitor the efficacy of the treatment.