Testing for autoantibodies against the accompanying proteins of the CASPR2 potassium channel is used in the investigation of patients with autoimmune encephalitis and Morvan syndrome.
The CASPR2 protein (Contactin Associated Protein-2) is a potassium channel complex (VGKC) subunit and is part of the extracellular antigen group. Antibodies against the CASPR2 antigen may occur in neurotoxicity, autoimmune encephalitis and Morvan 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 anger. The CASPR2 antibody titer can be used to monitor the efficacy of treatment.