LGI1 and CASPR2 neurological autoimmunity in children.

Area of Science:

• Neurology
• Immunology
• Pediatrics

Background:

• Leucine-rich glioma-inactivated protein 1 (LGI1) and contactin-associated proteinlike 2 (CASPR2) antibody-associated autoimmune neurological disorders are well-characterized in adults.
• Pediatric cases of LGI1 and CASPR2 antibody-associated autoimmunity are significantly underreported, with limited available data.

Purpose of the Study:

• To investigate the prevalence and clinical characteristics of LGI1 and CASPR2 antibody-associated autoimmune neurological disorders in a pediatric cohort.
• To compare the findings in children with those previously reported in adults.

Main Methods:

• Retrospective analysis of 13,319 pediatric patients tested for autoimmune neurological disorders between 2010 and 2017.
• Serological testing using radioimmunoprecipitation for voltage-gated potassium channel-complex-IgG.
• Confirmation of antibody positivity using transfected cell-binding assays for LGI1-IgG and CASPR2-IgG.

Main Results:

• Only 13 (4.9%) of seropositive pediatric patients were confirmed positive for LGI1-IgG, CASPR2-IgG, or both, a significantly lower rate than in adults.
• Common clinical manifestations included encephalopathy, seizures, and peripheral nerve hyperexcitability.
• Coexisting autoimmune conditions were frequent; however, faciobrachial dystonic seizures and cancers were not identified.

Conclusions:

• LGI1 and CASPR2 antibody-associated autoimmunity is rare in children compared to adults.
• Pediatric patients often present with encephalopathy and seizures, and frequently have other autoimmune conditions.
• Functional neurologic disorders were common initial diagnoses, and immunotherapy demonstrated potential benefit.