Table 1.

Respiratory chain complex activities in a patient with compound heterozygous variants in FOXRED1 presenting congenital lactic acidosis, cerebral cysts and pulmonary hypertension. CS = citrate synthase; CI = complex I, CII = Complex II, CIII=Complex III CIV = Complex IV, CV=Complex V CII + CII = succinyl cytochrome c oxydoreductase (combined activity of CII and CIII) for indirect measure of Coenzyme Q. % of patient value refers to median reference value.

Ratio	Normalized enzymatic activities
	Patient	Reference values range (Median) N = 12
CI/CII	0,13 (18%)	0,15–1,13 (0,70)
CII/CS	0,54 (135%)	0,32–0,50 (0,40)
CIII/CII	2,41(88%)	1,94–3,25 (2,75)
CII + CIII/CS	0,37 (112%)	0,29–0,47 (0,33)
CIV/CII	3,18 (82%)	2,80–4,39 (3,88)
CV/CII	0,90 (63%)	1,14–1,88 (1,43)