Novel variants and genotype-phenotype correlation in a multicentre cohort of GNE myopathy in China

BackgroundGlcNAc2-epimerase (GNE) myopathy is a rare autosomal recessive disorder caused by pathogenic variants in the GNEgene, which is essential for the sialic acid biosynthesis pathway.ObjectiveThis multi-centre study aimed to delineate the clinical phenotype and GNEvariant spectrum in Chinese patients, enhancing our understanding of the genetic diversity and clinical manifestation across different populations.MethodsWe retrospectively analysed GNEvariants from 113 patients, integrating these data with external GNEvariants from online databases for a global perspective, examining their consequences, distribution, ethnicity and severity.ResultsThis study revealed 97 distinct GNEvariants, including 35 (36.08%) novel variants. Two more patients with deep intronic variant c.862+870C>T were identified, while whole genome sequencing (WGS) uncovered another two novel intronic variants: c.52-8924G>T and c.1505-12G>A. Nanopore long reads sequencing (LRS) and further PCR analysis verified a 639 bp insertion at chr9:36249241. Missense variants predominantly located in the epimerase/kinase domain coding region, indicating the impairment of catalytic function as a key pathogenic consequence. Comparative studies with Japanese, Korean and Jewish, our cohorts showed later onset ages by 2 years. The high allele frequency of the non-catalytic GNEvariant, c.620A>T, might underlie the milder phenotype of Chinese patients.ConclusionsComprehensive techniques such as WGS and Nanopore LRS warrants the identifying of GNEvariants. Patients with the non-catalytic GNEvariant, c.620A>T, had a milder disease progression and later wheelchair use.