Table 1.

Respiratory chain enzyme activity measured in Subject 1 skeletal muscle and liver homogenates

	Complex I		Complex II		Complex II + III		Complex III		Complex IV		Citrate synthase (CS)
	Activity	% of CS activity	Activity	% of CS activity	Activity	% of CS activity	Activity	% of CS activity	Activity	% of CS activity	Activity
Sk muscle (n = 9 controls)	10 (19–72)	31	28 (26–63)	80	18 (30–76)	51	9.2 (13–51)	39	0.75 (3.3–9.1)	15	99 (85–179)
Liver (n = 6 controls)	11 (7.8–11.2)	71	79 (54–73)	80	n.t	n.t	11.1 (5.2–10.3)	90	1.35 (0.45–0.87)	123	44 (26–31)

Enzyme activities are displayed along with the control ranges (shown in brackets) and as % activity relative to citrate synthase activity. Values in bold are below the Major Criterion threshold for mitochondrial disease pathology in the Bernier Diagnostic Scheme (17).