P.044 GMPPB mutation causes a muscular dystrophy-myasthenic spectrum

Background: Mutations in GDP-Mannose Pyrophosphorylase B (GMPPB) cause a spectrum of disease ranging from muscular dystrophy to congenital myasthenic syndrome (CMS). Recognition neuromuscular junction dysfunction has important treatment implications. Methods: We describe person with GMPPB mutation causing an overlapping limb girdle - robust response acetylcholinesterase inhibitors. review the literature on CMS and explore phenotypic features that aid recognizing dysfunction. Results: A 35-year-old woman presented 10-year history debilitating myalgias, symmetrical neck weakness, chronic CK elevation. Electromyography showed non-irritable myopathy. Biopsies were consistent dystrophy. Whole genome sequencing revealed two heterozygous pathogenic mutations gene, giving diagnosis genetically confirmed Subsequently, repetitive nerve stimulation decrement trapezius muscle suggestive overlap syndrome. She was started pyridostigmine resulting recovery full motor power significant functional improvement. Conclusions: Identification caused by can significantly improve function. Early onset progressive fatigable proximal spared ocular facial muscles, responsiveness are GMPPB-related CMS.