Table 2.

Summary of defects observed in muscle in motor neuron diseases.

		SMA	ALS	SBMA
Muscle physiology	Muscle atrophy	✓	✓	✓
	Reduced strength	✓	✓	✓
	Mitochondrial dysfunction		✓ *
	Atrogene expression	✓	✓ *
	Sarcomere defects	✓ *
Development	Reduced Proliferation	✓ *
	Fusion defects	✓ *	✓ *	✓ *
	Aberrant expression of proteins important for muscle function	✓		✓
	Change in satellite cell number	✓ *
	Impaired postnatal growth	✓ *
Cell death	Increase in satellite cell apoptosis	✓ *
	Increase in cell death pathway expression	✓ *
	Myofiber degeneration			✓ *

^*Denotes defects that have been shown to be muscle intrinsic.