CNTNAP2 and Ataxia: Autoantibodies (aAbs) against contactin-associated protein-like 2 (CASPR2) are associated with various clinical syndromes including limbic encephalitis, Morvan syndrome, peripheral nerve hyperexcitability syndrome, ataxia, pain, and sleep disorders.1-3 CASPR2 aAb-mediated diseases often exhibit clinical relapses (25%) mostly observed if immunotherapy is discontinued.4,5