Lipid storage myopathy / 中华神经科杂志

ABSTRACT

Lipid storage myopathy (LSM) is an etiologically heterogeneous group of lipid metabolic disorders characterized by accumulation of light microscopic lipid droplets in muscle fibers.This disease seems to be more common in Chinese population accounting for 3％-5％ of total muscle biopsies in several large neuromuscular centers in China.The pathogenesis of LSM is the impairment of fatty acid oxidation in muscle fibers.Late-onset multiple acyl-coenzyme A dehydrogenase deficiency (MADD) caused by electron transfer flavoprotein dehydrogenase (ETFDH) gene mutation has been demonstrated to be the main molecular defect in China.Three frequent ETFDH mutations were identifiedc.250G＞A in patients from South China,and c.770A＞G and c.1227A＞C in those from both South and North China.More importantly,almost all late-onset MADD are dramatically responsive to riboflavin supplementation.Neutral lipid storage disease with myopathy (NLSDM) caused by mutations in PNPLA2 gene is the second common cause of Chinese LSM.Distal muscle involvement and asymmetrical muscle weakness and atrophy are common in primary symptoms of NLSDM which may be the first clue indicating the diagnosis of NLSDM.There were also a few case reports showing that LSM may be caused by carnitine transport defect and other deficiencies of acyl-coenzyme A dehydrogenase involved in fatty acid beta oxidation.Increased lipid droplets accumulation in muscle fibers may also be a secondary consequence of mitochondrial myopathy (mtDNA depletion syndrome or MELAS),dermatomyositis and steroid treatment.