Alfugham, Nora

AbstractBackgroundTo date, 10 patients with GTPase Regulator Associated with Focal Adhesion Kinase 1/Rho GTPase Activating Protein 26‐Immunoglobulin (GRAF1/ARHGAP26‐IgG) associated neurological disorders have been described, most with ataxia.ObjectiveTo report the clinical, oncological, and radiological associations of GRAF1 autoantibodies.MethodsWe identified 17 patients whose serum and/or cerebrospinal fluid IgG was confirmed to target GRAF1/ARHGAP26‐IgG by both tissue‐based immunofluorescence and transfected cell‐based assay. Clinical information was available on 14 patients.ResultsThe median age at neurological symptom onset was 51 years, and 8 (47%) were men. The predominant clinical features were subacute progressive cerebellar ataxia (13) or peripheral neuropathy (2). Magnetic resonance imaging brain (7 available) showed cerebellar atrophy (4, 1 also cerebrum and brainstem atrophy). Of 7 cerebrospinal fluids available for testing, 5 showed pleocytosis with oligoclonal bands in 3. Squamous cell carcinoma was observed in 3 patients (head and neck [2], lung [1]).ConclusionGTPase Regulator Associated with Focal Adhesion Kinase 1 autoimmunity manifests commonly with subacute ataxia and cerebellar degeneration with a potential association with squamous cell carcinoma. Peripheral neuropathy may also be encountered. Cases in this series responded poorly to immunotherapy.

Objective A novel autoimmune central nervous system (CNS) disorder with glial fibrillary acidic protein (GFAP)‐IgG as biomarker was recently characterized. Here, 102 patients with GFAP‐IgG positivity are described. Methods The 102 included patients had: (1) serum, cerebrospinal fluid (CSF), or both that yielded a characteristic astrocytic pattern of mouse tissue immunostaining; (2) confirmation of IgG reactive with specific GFAP isoforms (α, ɛ, or κ) by cell‐based assays; and (3) clinical data available. Control specimens (n = 865) were evaluated by tissue (n = 542) and cell‐based (n = 323) assays. Results Median symptom onset age was 44 years (range = 8–103), and 54% were women. The predominant phenotype (83 patients; 81%) was inflammation of meninges, brain, spinal cord, or all 3 (meningoencephalomyelitis). Among patients, highest specificity for those phenotypes was observed for CSF testing (94%), and highest sensitivity was for the GFAPα isoform (100%). Rare GFAP‐IgG positivity was encountered in serum controls by tissue‐based assay (0.5%) or cell‐based assay (1.5%), and in CSF controls by cell‐based assay (0.9%). Among patients, striking perivascular radial enhancement was found on brain magnetic resonance imaging in 53%. Although cases frequently mimicked vasculitis, angiography was uniformly negative, and spinal imaging frequently demonstrated longitudinally extensive myelitic lesions. Diverse neoplasms encountered were found prospectively in 22%. Ovarian teratoma was most common and was predicted best when both N‐methyl‐D‐aspartate receptor–IgG and aquaporin‐4–IgG coexisted (71%). Six patients with prolonged follow‐up had brisk corticosteroid response, but required additional immunosuppression to overcome steroid dependency. Interpretation GFAPα‐IgG, when detected in CSF, is highly specific for an immunotherapy‐responsive autoimmune CNS disorder, sometimes with paraneoplastic cause. Ann Neurol 2017;81:298–309