Footnotes

• Contributors II, BL and PM conceived and designed the study. II is the guarantor to the study. II, PM and SH have provided patient material. TCM, PW and BL carried out the laboratory work. TCM, AV, PM and BL conducted the assessment of data and the analysis. All authors were involved in the coordination of the study, read, contributed towards and approved the final manuscript.

• Funding Diabetes UK (II), Epilepsy Research UK (TCM and BL). NIHR Oxford Biomedical Research Centre.

• Competing interests AV and the Nuffield Department of Clinical Neurosciences in Oxford receive royalties and payments for antibody assays and AV is the named inventor on patent application WO/2010/046716 entitled ‘Neurological Autoimmune Disorders’. The patent has been licensed to Euroimmun AG for the development of assays for LGI1 and other VGKC-complex antibodies. PW and BL are coinventors and have received royalties. PW has received speaker honoraria from Biogen Idec and Euroimmun AG.

• Patient consent Obtained.

• Ethics approval Derbyshire Research Ethics Committee (ref 09/H0401/44).

• Provenance and peer review Not commissioned; externally peer reviewed.