Inherited muscular disorders can manifest at any age, from prenatal life to adulthood. The broad differential diagnosis includes muscular dystrophies, congenital myopathies, disorders of glycogen and lipid metabolism, channelopathies, and mitochondrial disorders. Muscular dystrophies may present at any age, are inherited, and involve progressive degeneration of muscle, which is often replaced by connective tissue. Muscular dystrophies result from defects in the sarcolemmal proteins of muscle, including dystrophin-associated muscle membrane protein complex, muscle intracellular proteins (eg, nuclear envelope proteins), and extracellular matrix proteins (eg, collagen VI).