Table 1.

Initial presentation.

	Patient	Sex	Mutations	Age of Onset	Age at Dx	Brain MRI	Biochemical Investigations	Enzyme Activity (Fibroblasts)	Developmental Delay	Regression	Seizures	Dystonia	Visual Impairment	Hearing Loss	Cardiomyopathy	GT Feedings	Clinical Course
HIBCH	1	M	c.196C > T p.(Arg66Trp) c.196C > T p.(Arg66Trp)	5 m	13 y	Leigh's	Normal lactate and PDHC ↑ C4OH	↓	Yes	Yes	No	Yes	Yes	No	No	Yes	Severe, progressive
	2	F	c.196C > T p.(Arg66Trp) c.196C > T p.(Arg66Trp)	6 m	12 y	Leigh's	Normal lactate, ↑ C4OH	↓	Yes	Yes	No	Yes	Yes	No	No	Yes	Severe, progressive
ECHS1	3	M	c.832G > A p.(Ala278Thr) c.489G > A p.(Pro163=)	15 m	6 y	Leigh's	Intermittent lactic acidosis & ketosis	↓	Yes	Yes	No	Yes	Yes	No	No	Yes	Severe, progressive
	4	M	c.832G > A p.(Ala278Thr) c.489G > A p.(Pro163=)	6 m	13 y	Leigh's	Intermittent lactic acidosis & ketosis	↓	Yes	Yes	No	Yes	Yes	No	No	No	Moderate, progressive
	5	M	c.849_852del p.(Lys284Profs*31) c.713C > T p.(Ala238Val)	11 m	3 y	Leigh's	Intermittent lactic acidosis & ketosis	ND	Yes	Yes	Yes	Yes	Yes	Yes	No	Yes	Severe, progressive

PDHC: Pyruvate dehydrogenase complex, ND: Not done