metabolic crises, recurrent, with variable encephalomyopathic features and neurologic regression (EFO_0010255, an Experimental Factor Ontology identifier) is an autosomal recessive disease characterized by muscle weakness, developmental delay, lactic acidosis, and encephalopathy. The severity of the clinical manifestations is highly variable even within affected individuals of the same family, ranging from asymptomatic lactic acidosis to severe developmental regression, epilepsy, intellectual disability, metabolic crisis, and multiorgan involvement.