Monarch Disease Ontology identifier MONDO_0016814 (maternally-inherited Leigh syndrome) can be described as follows. Maternally inherited Leigh syndrome is a rare subtype of Leigh syndrome characterized clinically by encephalopathy, lactic acidosis, seizures, cardiomyopathy, respiratory disorders and developmental delay, with onset in infancy or early childhood, and resulting from maternally-inherited mutations in mitochondrial DNA. Also known as: MILS, maternally-inherited Leigh disease, maternally-inherited infantile subacute necrotizing encephalopathy.