Clinical and laboratory findings in patients with anti-myelin oligodendrocyte glycoprotein antibodies: experience from two tertiary hospitals in Madrid.

Background/Objective: This study aimed to describe the clinical, radiographic and laboratory characteristics of a cohort of patients diagnosed with anti-myelin oligodendrocyte glycoprotein (anti-MOG) antibodies at two collaborating centers in Madrid (Spain). Besides the study of anti-MOG antibodies in serum and cerebrospinal fluid sample (CSF), this study highlights the results of the cytochemical study of CSF, kappa free light chain (κ-FLC) index and oligoclonal bands (OCBs). Methods: Records of patients diagnosed with anti-MOG antibodies at Hospital General Universitario Gregorio Marañón and Hospital Universitario Ramón y Cajal between 2018 and 2024 were retrospectively reviewed. Results: The cohort comprised fifteen patients. Of those patients, nine (60%) were female, ten (67%) were Caucasian, and four (27%) were children. The mean age at onset was 46 years (range, 1-66 years). Optic neuritis was the most common presentation, identified in eleven patients (73%). A clear positive MOG-IgG titer was identified in serum samples of ten patients; also, a positive result was found in a CSF sample of one patient. CSF analysis showed CSF-OCBs in three patients, low positive κ-FLC index in three patients, elevated protein in two patients, and pleocytosis in another two patients. Relapses were reported in seven patients (46.6% of patients), all of whom were female patients. Discussion: This study provides valuable insights into the characteristics observed in patients diagnosed with anti-MOG antibodies in Spain. Results are discussed in the context of the 2023 international diagnostic criteria for MOGAD and previously published cohort studies.