IgM anti-GM2 antibodies have been described throughout the spectrum of immune-mediated neuropathies, including Guillain-Barré syndrome (GBS) and its acute motor axonal variants, chronic inflammatory demyelinating polyneuropathy, and sensory demyelinating neuropathy with ataxia [20, 21, 32, 34–38]. This evidence concerns the gene CD40LG and chronic inflammatory demyelinating polyradiculoneuropathy.