Short ReportFGFR3 Antibodies in Neuropathy: What to Do With Them?Samara, Verena MD; Sampson, Jacinda MD; Muppidi, Srikanth MDAuthor Information Department of Neurology and Neurosciences, Stanford Medical Center, Palo Alto, CA. Reprints: Srikanth Muppidi, MD, Stanford Neurosciences Health Center, 213 Quarry Road, 2nd Floor, Palo Alto, CA 94304 (e-mail: [email protected]). The authors report no conflicts of interest. S. Muppidi: Advisory Board meetings for Lundbeck, Alexion, and Alnylam. Journal of Clinical Neuromuscular Disease: September 2018 - Volume 20 - Issue 1 - p 35-40 doi: 10.1097/CND.0000000000000221 Buy Metrics Abstract Objectives: To describe the variability of fibroblast growth factor receptor 3 (FGFR3) antibody titers in a small series of patients. Methods: We performed a retrospective review of patients with neuropathy and positive FGFR3 antibodies. Results: We report 7 patients (3 women) with an age range 44–81 years. Symptoms were acute onset in 3 and subacute onset in 4 patients. Five had neuropathic pain. Examination revealed normal large fiber function to mild/moderate predominantly sensory neuropathy and ataxia in one patient. Electrodiagnostic studies revealed normal large fiber function (3), demyelinating neuropathy (1), and mild/moderate axonal neuropathy (3). Four patients had high and 3 patients had low FGFR3 titers. Repeat testing revealed absence of antibodies in 2 patients and a significant reduction in one patient without any intervening immunotherapy. Conclusions: Our case series highlights the variability and inconsistency in FGFR3 antibody titers through enzyme-linked immunosorbent assay testing. These antibody titers should always be interpreted with caution in clinical context. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.