Novel Pathogenic Variants in a French Cohort Widen the Mutational Spectrum of GNE Myopathy

BACKGROUND GNE myopathy is a rare autosomal recessively inherited muscle disease resulting from mutations in the gene encoding GNE (UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase), a key enzyme in sialic acid biosynthesis. 154 different pathogenic variants have been previously associated with GNE myopathy. OBJECTIVE Describe novel pathogenic variants associated with GNE myopathy in a large French cohort. METHODS We analyzed mutational data from 32 GNE myopathy index patients. Novel, as well as previously published pathogenic variants, were examined for possible deleterious effects on splicing. RESULTS We describe 13 novel pathogenic variants in GNE, identified in the first large French cohort reported to date. We also find that 6 published pathogenic variants might have a previously unrecognized deleterious effect on splicing. CONCLUSIONS Novel pathogenic GNE variants described here raise the total number of different pathogenic variants reported to 167, complementing the recently published GNE mutation update. Our novel findings on possible splice-disrupting effects by several variants suggest that the pathogenicity mechanism of these variants could be reinterpreted, expanding our knowledge about the GNE mutational spectrum.