003 Autoimmune encephalitis antibody biomarkers: frequency, age and sex associations

Objective To determine the frequency, age and sex associations for autoimmune encephalitis antibody biomarkers (AE-Abs). Methods There were 42032 patients tested in the Mayo Clinic Neuroimmunology Laboratory between January 2018-December 2019 for AE-Abs in serum and/or cerebrospinal fluid (CSF) including; NMDA-R-IgG, AMPA-R-IgG, GABAB-R-IgG, CASPR2-IgG, LGI1-IgG, GAD65-IgG, CRMP5-IgG, amphiphysin-IgG, PCA1/2/Tr-IgGs, ANNA1/2/3-IgGs, GFAP-α-IgG, mGluR1-IgG, DPPX-IgG, MOG-IgG1, were examined to determine frequency of antibody positivity. Age and sex associations were examined using multivariable logistic regression. Results Adult serum analysis (22,472 patients; 56% female) revealed 814 (4%) were positive: NMDA-R-IgG (25%) > GAD65-IgG (22%) > LGI1-IgG (21%) > others. Of children (5,649; 50% female), 250 (4%) were positive: NMDA-R-IgG (53%) > MOG-IgG1 (32%) > GAD65-IgG (7%) > others. Adult CSF analysis (18,745 patients; 54% female) revealed 709 (4%) were positive; NMDA-R-IgG (45%) > GAD65-IgG (19%) > LGI1-IgG (13%) > others. Of children (5136; 50% female), 276 (5%) were positive: NMDA-R-IgG (90%) > GAD65-IgG (7%) > others. Age 65 years was associated with GABAB-R-IgG, LGI1-IgG, CASPR2-IgG and ANNA1-IgG (OR=7.33, 14.98, 3.67, 14.53, p Conclusion The most frequently detected were NMDA-R-IgG, LGI1-IgG, GAD65-IgG and MOG-IgG1. Age and sex associations may suggest paraneoplastic, endocrinological or aging influences on neurological autoimmunity.