Antineurofascin IgG2-associated paediatric autoimmune nodopathy.

In this case series of four paediatric patients, we present the first described cases of immunotherapy-responsive autoimmune nodopathy with IgG2 antineurofascin antibodies. In three cases, the antineurofascin antibodies were predominantly of the IgG2 subclass, a novel finding in comparison to previously described adult cases where IgG4 and/or IgG1/3 have typically been described. One patient had low signal for IgG2 with predominant IgG1 and IgG4 antibodies, a pattern commonly seen in adult patients. Two patients had antibodies targeting all three neurofascin isoforms (155, 186, and 140), whereas antibodies in the sera from the third targeted only the nodal isoforms 186 and 140, and the fourth patient only neurofascin 155. The three patients with IgG2 predominant antibodies appear to be responsive to intravenous immunoglobulin (IVIG) to varying degrees thus far, whereas the patient with IgG1/4 antibodies had poor response to IVIG but good response to steroids. Although the full clinical significance of IgG2 predominant antineurofascin antibodies in the context of childhood polyneuropathy remains unclear, emerging evidence of serological-phenotypic correlation may inform prognostication and therapeutic decision-making, warranting further study into this area.