CD40LG and acute disseminated encephalomyelitis: M. pneumoniae–associated acute disseminated encephalomyelitis was reported with strongly positive anti-GM2 IgM antibodies, which lead to chronic motor neuropathy, amyotrophic lateral sclerosis–like disorder after ganglioside therapy, chronic demyelinating neuropathy with sensory ataxia, paraneoplastic polyradiculoneuritis, and Guillain–Barré syndrome (Xia and Chen, 2020).