RT Book, Section A1 Abid, Farida A1 Lotze, Timothy E. A2 Kline, Mark W. SR Print(0) ID 1182924205 T1 Myopathies T2 Rudolph's Pediatrics, 23e YR 2018 FD 2018 PB McGraw-Hill Education PP New York, NY SN 9781259588594 LK accesspediatrics.mhmedical.com/content.aspx?aid=1182924205 RD 2024/03/29 AB Myopathies are disorders of the skeletal muscle due to a structural or metabolic abnormality of the muscle cells resulting in muscle weakness and dysfunction. They can be due to hereditary or acquired causes. This chapter will focus specifically on inherited forms of myopathies. Inherited myopathies relate to specific genetic defects affecting 1 of many areas involved in the integrity of the muscle. These include genes related to proteins of ion channels (eg, sodium channels), sarcolemma membrane (eg, dystrophin), sarcomere (eg, actin or myosin), or nuclear membrane (eg, emerin). In addition, some inherited myopathies are caused by impaired muscle metabolism of carbohydrates, lipid, or the mitochondrial electron transport chain. Myopathies are named based on the classical description (eg, Duchenne and Becker muscular dystrophy), their phenotype to include the distribution of weakness (eg, limb-girdle muscular dystrophy or facioscapulohumeral dystrophy), or the specific underlying genetic defect (eg, laminopathy secondary to LMNA mutations). This latter descriptor has some particular relevance as newer genetic methods have expanded the previously narrow spectrum of phenotypes associated with a particular gene.