Updates on Mitochondrial Disorders in Children

Each human cell contains a few hundred mitochondria that are essential for aerobic energy metabolism. Among many fundamental metabolic pathways in mitochondria, the oxidative phosphorylation (OXPHOS) or the respiratory chain (RC) represents the final stage in oxidative metabolism. RC is under the dual control of the mitochondrial genome (mtDNA) and the nuclear genome (nDNA). The proper assembly and functioning of the RC involve many steps. The genetic defects in mtDNA, nDNA, and related functions of mitochondria affect the functioning of RC resulting in insufficient energy production and organ dysfunction. Mitochondrial disorders are increasingly recognized. The clinical manifestations vary widely, causing a significant diagnostic challenge. Manifestations range from lesions of single tissue or structure to widespread lesions, including myopathies, encephalomyopathies, cardiopathies, neurogastrointestinal form, psychiatric symptoms, or complex multisystem syndromes. Coenzyme Q10 deficiency may present with isolated proximal muscle weakness. Leigh syndrome and MELAS are the most common clinical multisystem syndromes. The age at onset ranges from neonatal to adult life. The mortality remains high, and the median survival for early onset severe disease is 12years. Initial evaluations include blood transaminases, lactate-to-pyruvate ratio, amino acids, acylcarnitine profile, creatine kinase, and organic acids. Genetic tests are needed for confirmation. Treatment depends on the specific mitochondrial disorder and its severity. In an acute presentation, an infection should be sought and treated promptly. Coenzyme Q10, thiamine, riboflavin, lipoic acid, L-carnitine, Creatine, and L-Arginine are found to be beneficial. Although there are no cures, treatments reduce symptoms or slow the decline in health. nbsp;