Mitochondrial Leigh syndrome: the state of the art

BACKGROUND: Leigh syndrome or subacute necrotizing encephalomyelopathy was first recognized as a neuropathological entity in 1951. It is a progressive neurological disease characterized by neuroradiological lesions, particularly in the brainstem and basal ganglia. Leigh's syndrome is a pan-ethnic disorder with onset usually in infancy or early childhood. Over the last six decades, this complex neurodegenerative disorder has been shown to comprise >100 separate monogenic disorders associated with enormous clinical and biochemical heterogeneity. This article reviews clinical, radiological, biochemical and genetic aspects of the disorder. OBJECTIVES: this overview provides a better understanding of this rare mitochondrial disease by identifying its clinical, radiological and genetic manifestations in order to improve early diagnosis, patient follow-up and genetic counseling. METHODOLOGY: systematic literature review RESULTS: Leigh syndromes present with childhood developmental regression, a loss of previously achieved developmental milestones. Numerous non-neurological manifestations of Leigh syndrome have been reported, many of which are related to the underlying genetic defects. These include cardiomyopathy, renal tubulopathy, gastrointestinal and endocrine dysfunction, and liver disease. Known genetic causes, including defects in 16 mitochondrial DNA (mtDNA) genes and nearly 100 nuclear genes, are categorized into disorders of subunits and assembly factors of the five oxidative phosphorylation enzymes, disorders of pyruvate metabolism and vitamin and cofactor transport and metabolism, disorders of mtDNA maintenance, and defects in mitochondrial gene expression, protein quality control, lipid remodeling, dynamics and toxicity. An approach to diagnosis is presented, together with known treatable causes and an overview of current supportive management options and emerging therapies on the horizon CONCLUSION: Management of mitochondrial diseases must be multidisciplinary, and in collaboration with a center of reference (CRMR) or a center of competence (CCMR) with expertise in mitochondrial diseases.