Noriko Onoue

By Ryosuke Tashiro, Noriko Onoue and Tsuyoshi Shinozaki

Mitochondrial diseases are multisystem disorders, resulting from mitochondrial electron transport chain dysfunction and oxidative phosphorylation due to pathogenic variants in mitochondrial or nuclear DNA. The clinical presentations are variable in the age of onset, symptoms, and range and severity of organ involvement. Diagnosis requires a multidisciplinary approach and is based on clinical symptoms, laboratory tests, histopathological findings, and genetic analysis. Due to the multi-organ involvement, the evaluation of mitochondrial diseases should include a systemic screening for all targeted organs, including neuroimaging, ophthalmology, and hearing examinations. Cardiac involvement should be evaluated at the time of diagnosis, as cardiac involvement is an independent predictor of morbidity and early mortality, even in asymptomatic cases. Hypertrophic cardiomyopathy is the most common cardiac manifestation; however, mitochondrial cardiomyopathy might also present as left ventricular non-compaction (LVNC) or as dilated, histiocytoid, or restrictive cardiomyopathy. The precise evaluation of cardiac involvement is of clinical use in predicting future cardiac events and prognosis. Despite advancements in molecular biology, no satisfactory treatments for mitochondrial diseases exist. Treatment remains largely symptomatic and does not significantly alter disease progression.

Part of the book: Current Perspectives on Cardiomyopathies