Introduction: In adults, VGKC-complex antibodies are associated with limbic encephalitis (LE), neuromyotonia and Morvan’s Syndrome. Many of the antibodies bind to the VGKC-associated proteins LGI1 and CASPR2¹.  In children, the VGKC-complex antibodies have been identified in a wider range of encephalopathies, seizure disorders and autistic regression. Our objective was to systematically identify the associated clinical phenotypes in 2 London paediatric neurology centres.

Method: From 2007-2013, 363 serum samples were tested for VGKC-complex antibodies. Patient notes were reviewed retrospectively and patients were grouped by their primary diagnosis to either inflammatory (n= 159) or non-inflammatory (n=204) aetiologies.

Results: 39/363 (11%) of the patients tested were VGKC-complex antibody positive, and presented with encephalopathy (n=18), acute demyelinating syndrome (n=6), movement disorder (n=4), neuromuscular syndromes (n=5), seizure disorders (n=3) and others (n=3).  These antibodies were positive in 31/159 patients with inflammatory conditions compared with only 8/204 in the non-inflammatory group. (p <0.0001, Fisher’s exact). Only one child who presented with GBS was positive for the associated proteins (LGI1 and CASPR2).  Of the 18 VGKC-antibody positive patients with encephalopathy; 3 had LE (one with additional neuromyotonia). An additional antibody was present: NMDAR in one, GAD in one and TPO in three.  None had an underlying neoplasm.

Conclusion: Positivity of VGKC-complex antibodies in children does not indicate a specific clinical syndrome and the VGKC-associated proteins are mostly negative.  Nevertheless, these antibodies that are identified more frequently in primary inflammatory disorders, can be useful non-disease specific biomarker of inflammation that may be immunotherapy responsive.