Supplementary table 1: Individual clinical symptoms and outcome (order by age at first symptoms). Since elevated lactate, metabolic acidosis, FTT and developmental delay were present in all patients, these symptoms are not listed. (Unfilled fields = no data available)

Patient
ID / Sex / Age at first presentation
d=days
mo=months / Dysmorphic features
(reported by physicians) / Other specific symptoms / Metabolic treatment / Muscular hypotonia / Severely impaired
speech / No ambulation / Age (mo) at last follow-up / Deceased at age
(mo)
1 / F / 1 d / Almond shaped eyes, high arched palate, short forehead, mild synophrys, infraorbital crease, broad nasal bridge, anteverted nostrils and micrognathia / Non-progressive cardiomyopathy / Biotin; Carnitine; Coenzyme Q10; Riboflavin; Sodiumbicarbonate; Thiamine / + / + / + / 24
2 / M / 1 d / Low set ears, broad nasal bridge, almond shaped eyes, mild synophrys / Coenzyme Q10; Vit D3, Riboflavin; Thiamine; / + / + / + / 37
4$ / M / 1 d / Hypospadia, low set ears, smooth philtrum, pectusexcavatum, small hands and feet, short stature / Carnitine; Coenzyme Q10; Riboflavin / + / + / + / 57
5 / M / 1 d / Low set ears, long philtrum, curved eyebrows, hypertelorism, high forehead, broad nasal bridge, thickened ear helix / No treatment / + / + / + / 55
7$ / F / 1 d / Low set ears, saddle nose, long philtrum,downward slanted eyelids / Hypertrophic cardiomyopathy / Carnitine; Coenzyme Q10; Riboflavin; Sodiumbicarbonate / + / + / + / 36
9$ / M / 1 d / Low set ears , curved, prominent eyebrows, hypertelorism, broad nasal bridge / Bezafibrate; Biotin; Folinate; Carnitine; Coenzyme Q10; Riboflavin; Thiamine;
Vit C; Vit D / + / + / + / 26
10 / F / 1 d / Low set ears, smooth philtrum, small hands and feet / Coenzyme Q10; Riboflavin; Fat rich diet (55%) / + / + / + / 27
13 / M / 1 d / none / Hypoplastic cerebellum / No treatment / + / Unknown / Unknown / Unknown
16 / M / 1 d / none / Borderline left-ventricular hypertrophy and hyperdynamic left ventricular function / Carnitine; Coenzyme Q10 / + / + / + / 37
21 / F / 1d / Short stature, microcephaly, facial dysmorphia, synophrys, strabism, hypertrichosis, thyroglossal cyst / Episodic neutropenia, infections, sensorineural hearing loss, optic atrophy, visual impairment, stroke at age 10 years / Coenzyme Q10; Riboflavin, L-arginine, L-Citrulline, Sodiumbicarbonate / + / + / + / 153
17 / M / 2 d / Turricephalus, large anterior fontanelle, blepharophimosis, hypertelorism, epicanthus, broad nasal bridge, low set ears, high-arched palate, broad mouth, short stature, short proximal limbs, cryptorchidism, hypoplastic scrotum, nevus flammeus left arm / Neutropenia, wound healing deficit, recurrent infections. Fatal gastrointestinal bleeding. / No treatment / unknown / + / 75
20 / F / 2d / none / Non-obstructive hypertrophic cardiomyopathy; hypoplastic cerebellum / Coenzyme Q; Thiamine; Propanolol / + / - / n.a. / 2
12 / F / 3 d / Craniofacial abnormalities / No treatment / + / Unknown / Unknown / 24
3 / M / 3 mo / none / No treatment / - / - / + / 45
19 / M / 4.5 mo / Long hair line anteriorly, hypertelorism, long smooth philtrum, high arched palate, flat nasal bridge / Sodiumbicarbonate / + / + / 45
14 / M / 5 mo / Frontal bossing, bitemporal narrowing, esotropia / Carnitine; Coenzyme Q10 / + / + / Assisted / 58
6 / M / 6 mo / Craniofacial abnormalities / Bilateral cataracts / No treatment / + / + / + / 24
18* / M / 12 mo / none / Small ASD&VSD / Sodiumcitrate;
Sodiumbicarbonate / + / + / + / Unknown
15 / F / 17 mo / none / Cardiomyopathy / Sodiumcitrate;
Low protein diet / + / + / + / 55
11 / M / 24 mo / Craniofacial abnormalities / Bilateral congenital cataracts / No treatment / + / Unknown / Unknown / 24
8 / F / Unknown / none / No treatment / Unknown / + / Unknown / Unknown

$$Published as patients 7, 8 and 9 in Gai et al (2013); *published as “S3” in Bonnen et al (2013)