Motor-neuron-disease-like phenotype associated with IgLON5 disease.

A growing spectrum of neurological manifestations are being recognized in association with IgLON5 autoimmunity, including recent reports of motor-neuron-disease-like phenotype. Here we describe four cases of IgLON5 autoimmunity with motor neuron involvement and evaluate an additional 109 probable or definite amyotrophic lateral sclerosis cases seen in our neuromuscular clinic for IgLON5-IgG seropositivity. The presence of parasomnias, vocal cord dysfunction or hyperkinetic movements in a patient with motor-neuron-disease-like phenotype should prompt evaluation for IgLON5-IgG autoantibodies. Recognition and treatment of this autoimmune disease with immunosuppressive agents may bring about significant neurological improvement in a minority of cases.