TY - JOUR T1 - Frequency of MOG-IgG in cerebrospinal fluid versus serum JF - Journal of Neurology, Neurosurgery & Psychiatry JO - J Neurol Neurosurg Psychiatry SP - 334 LP - 335 DO - 10.1136/jnnp-2021-326779 VL - 93 IS - 3 AU - Samuel Pace AU - Michael Orrell AU - Mark Woodhall AU - Jacqueline Palace AU - Maria Isabel Leite AU - Sarosh R Irani AU - Patrick Waters AU - Adam E Handel Y1 - 2022/03/01 UR - http://jnnp.bmj.com/content/93/3/334.abstract N2 - Immunoglobulin gamma autoantibodies directed against myelin oligodendrocyte glycoprotein (MOG-IgG) are associated with specific neurological syndromes, most frequently acute disseminated encephalomyelitis, optic neuritis and longitudinally extensive transverse myelitis.1 For all neurological surface-directed autoantibodies, including MOG-IgG, serum concentrations are higher than cerebrospinal fluid (CSF), consistent with their peripheral generation. Hence, in the UK, CSF testing is not routine in clinical practice. However, recent studies have reported patients with CSF MOG-IgG but without detectable serum MOG-IgG.2 3 The prevalence and clinical relevance of this finding is unclear. We aimed to address this by analysing MOG-IgG results in all paired serum and CSF samples from our national testing database.We audited the database of MOG-IgG cell-based assay (CBA) requests from the Oxford Autoimmune Neurology Diagnostic Laboratory between 2011 and 2019. These data encompassed all samples referred to the centre for MOG-IgG testing by physicians over this time period. Serum samples were available from 272 centres, mostly within the UK, and CSF from 97 centres without clear referral bias. MOG-IgG testing was performed using a cell-based assay as previously described, modified to detect MOG-IgG1 since 2014.4 CSF was assayed undiluted. Positive or negative MOG-IgG results were available for 22 554 patients; in 533/22 554 (2.4%) the results were in paired serum and CSF (defined as those taken within 31 days of one another). Data were analysed in R with estimated 95% CIs derived from DescTools (Wilson’s method with continuity correction).For patients with negative serum and positive CSF MOG-IgG results, the patient’s general practitioner and referring neurologists supplied case notes and test results from which pre-specified clinical and paraclinical parameters were extracted (age, gender, clinical manifestations of … ER -