We describe a patient with ocular myasthenia gravis, where single-fiber electromyography and testing for acetylcholine receptor and muscle-specific kinase antibodies were negative. However, antibodies to low-density lipoprotein receptor-related protein 4 (LRP4) were positive, and this prompted appropriate management. We recommend that testing for LRP4 antibodies be considered when the clinical suspicion for myasthenia gravis is high despite negative conventional diagnostic tests.
Department of Ophthalmology (JMK), Hadassah Medical Center, Kiryat Hadassah, Jerusalem, Israel; Neuroimmunology and Cell Therapy Unit (DK, PP), Neurology Department, Hadassah-Hebrew University Medical Center, Jerusalem, Israel; and Department of Neurobiology (PZ), Hellenic Pasteur Institute, Greece and Tzartos NeuroDiagnostics, Athens, Greece.
Address correspondence to Joshua M. Kruger, MD, PhD, Department of Ophthalmology, Hadassah Medical Center, Kiryat Hadassah, PO Box 12000, Jerusalem, 91120, Israel; E-mail: email@example.com
P. Zisimopoulou is coinventor in a patent related to myasthenia gravis therapy and diagnosis, and is an employee of Tzartos Neurodiagnostics. The remaining authors report no conflicts of interest.