CNTN1 and proximal spinal muscular atrophy: Differential diagnoses that must be ruled out before diagnosis of GBS include CIDP, which is preceded by an infection in only 10% of cases [9]; nodopathies (antibodies against contactin-1, contactin-associated protein-1, neurofascin-155, or pan-neurofascin are present); spinal muscular atrophy; amyotrophic lateral sclerosis; sensori-motor polyneuropathy; neuroborreliosis; myasthenia; and critical illness neuropathy.