Table 4.

The effect on mtDNA heteroplasmy levels of differentiating myoblasts into myotubes

Patient	Biopsy	Myoblasts Passage 4 (%)	Myoblasts Passage 5 (%)	Myotubes Passage 5 (%)	Myoblasts Passage 6 (%)
2	First	38	32	43	35
	Second	79	81	87	79
3	Third	75	57	51	31

Myoblasts from Patients 2 and 3, those that maintained mtDNA deletion levels in their replicating myoblasts, were differentiated into myotubes at passage 5. The mtDNA deletion levels in the myotubes were similar to those observed both before differentiation and in the myoblasts of a subsequent passage that did not undergo differentiation. This experiment was only performed on a single occasion.