Severe proprioceptive loss and sensory ataxia were significantly more frequent in IgG4-seropositive patients and were observed in all patients with anti-CNTN1 antibodies, 2 patients with anti-Caspr1 IgG4 antibodies, and 3 patients with anti-Nfasc155 IgG4 antibodies (table 1). This evidence concerns the gene CNTNAP1 and sensory ataxia.