Altered skeletal muscle (mitochondrial) properties in patients with mitochondrial DNA single deletion myopathy

Table 2 Clinical and molecular characteristics of patients with mitochondrial myopathy

Patient	Sex	Age of onset (yr)	Diagnosis	Clinical features	[CK]_rest (U L⁻¹)	[L⁻]_rest(mmol L⁻¹)	Genetic defect	Mutant mtDNA	Muscle biopsy
1	f	20	CPEO	ptosis, external ophthalmoplegia, facial weakness, slight general weakness	219	normal	mtDNA deletion 4977 bp	> 95 %	COX⁻, ragged blue fibers
2	m	33	CPEO	ptosis, external ophthalmoplegia, general weakness, exercise intolerance	401	normal	mtDNA deletion 4405 bp	90 %	unremarkable
3	f	62	MM	mild proximal lower extremity weakness	normal	normal	mtDNA deletion 5–13 kbp	49–71 %	COX⁻, ragged blue fibers
4	f	12	MM	exercise induced myalgia	206	normal	mtDNA deletion 10–13 kbp	35 %	COX⁻, SDH⁺, ragged red fibers
5	f	20	MM	exercise induced myalgia	normal	normal	mtDNA deletion 6–10 kbp	62 %	ragged red fibers
6	f	39	MM	exercise induced myalgia	normal	5.3	mtDNA deletion 8–12 kbp	12–36 %	unremarkable

[CK], blood creatine kinase concentration at rest; COX ⁻ cytochrome oxidase negative fibers, CPEO chronic progressive external ophthalmoplegia, [L⁻], blood lactate concentration at rest; MM mitochondrial myopathy, mtDNA mitochondrial DNA, SDH ⁺ succinate dehydrogenase positive fibers