A myopathy with unusual features caused by PNPLA2 gene mutations |
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| Authors: | Elena M. Pennisi MD PhD Sara Missaglia PhD Salvatore Dimauro MD Cinzia Bernardi MD Hasan Orhan Akman PhD Daniela Tavian PhD |
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| Affiliation: | 1. Division of Neurology, San Filippo Neri Hospital, Rome, Italy;2. Laboratory of Cellular Biochemistry and Molecular Biology, Catholic University of the Sacred Heart, Milan, Italy;3. Department of Neurology, Columbia University Medical Center, New York, New York, USA;4. Psychology Department, Catholic University of the Sacred Heart, Milan, Italy |
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| Abstract: | Introduction: The PNPLA2 gene encodes the enzyme adipose triglyceride lipase (ATGL), which catalyzes the first step of triglyceride hydrolysis. Mutations in this gene are associated with an autosomal recessive lipid‐storage myopathy, neutral lipid‐storage disease with myopathy (NLSD‐M). Results: A 72‐year‐old woman had late‐onset myopathy, with mild weakness, cramps, and exercise intolerance. Electromyography showed myotonic discharges. A few leukocytes showed lipid droplets (Jordan anomaly). Deltoid and quadriceps muscle biopsies showed no lipid storage. Genetic analysis of PNPLA2 detected 2 heterozygous mutations: c.497A>G (p.Asp166Gly) in exon 5 and c.1442C>T (p.Pro481Leu) in exon 10. Expression of mutant PNPLA2 plasmids in HeLa cells resulted in impaired enzyme activity, confirming the pathological effects of the mutations. Conclusions: In this case of NLSD‐M, the myopathy may be due to a metabolic defect rather than to a mechanical effect of lipid storage. This suggests that more than 1 mechanism contributes to muscle damage in NLSD‐M. Muscle Nerve 51: 609–613, 2015 |
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| Keywords: | ATGL enzyme lipid metabolism lipid myopathy lipid storage PNPLA2 gene |
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