TNFSF13B and opsoclonus-myoclonus syndrome: Because certain treatments alter CSF BAFF concentrations, the analysis was then performed only for untreated OMS, for which there were 10 ‘high’ and 34 ‘normal,’ with non-significant trends: CSF CXCL13 (P = 0.06), serum CXCL9 (P = 0.08).