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Clinical utility of RNA sequencing to resolve unusual GNE myopathy with a novel promoter deletion
Journal article   Peer reviewed

Clinical utility of RNA sequencing to resolve unusual GNE myopathy with a novel promoter deletion

Samya Chakravorty, Kiera Berger, Dalia Arafat, Babi Ramesh Reddy Nallamilli, Hari Prasanna Subramanian, Soumya Joseph, Mary E Anderson, Kevin P Campbell, Jonathan Glass, Greg Gibson, …
Muscle & nerve, Vol.60(1), pp.98-103
07/2019
DOI: 10.1002/mus.26486
PMCID: PMC7688010
PMID: 30990900
url
https://www.ncbi.nlm.nih.gov/pmc/articles/7688010View
Open Access

Abstract

ABSTRACT\nIntroduction: UDP N‐acetylglucosamine2‐epimerase/N‐acetylmannosamine‐kinase (GNE) gene mutations can cause mostly autosomal‐recessive myopathy with juvenile‐onset known as hereditary inclusion‐body myopathy (HIBM). Methods: We describe a family of a patient showing an unusual HIBM with both vacuolar myopathy and myositis without quadriceps‐sparing, hindering diagnosis. We show how genetic testing with functional assays, clinical transcriptome sequencing (RNA‐seq) in particular, helped facilitate both the diagnosis and a better understanding of the genotype‐phenotype relationship. Results: We identified a novel 7.08 kb pathogenic deletion upstream of GNE using array comparative genomic hybridization (aCGH) and a common Val727Met variant. Using RNA‐seq, we found only monoallelic (Val727Met‐allele) expression, leading to ~50% GNE reduction in muscle. Importantly, α‐dystroglycan is hypoglycosylated in the patient muscle, suggesting HIBM could be a “dystroglycanopathy.” Conclusions: Our study shows the importance of considering aCGH for GNE‐myopathies, and the potential of RNA‐seq for faster, definitive molecular diagnosis of unusual myopathies. Muscle Nerve, 2019
molecular diagnostics transcriptome sequencing (RNA‐seq) next generation sequencing aCGH myositis GNE myopathy (HIBM)

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