Table 1. Biochemical assessment of the patient’s muscle biopsy.

Enzyme	Representing	Activity	Normal range
Citrate synthase	Mitochondrial matrix marker	232	43 to 132
NADH:CoQ oxidoreductase	Respiratory complex I	54	17.3 to 45.1
NADH:O2 oxidoreductase	Respiratory complex I/III/IV	8.4	11.4 to 48
Succinate:cytochrome c oxidoreductase	Respiratory complex II/III	11.2	8.8 to 35.9
Cytochrome c oxidase	Respiratory complex IV	2.9	105 to 279