Introduction and current guidance

Advice

Mitochondria are responsible for converting food into energy within human cells. Mitochondrial disorders are a diverse group of conditions that often involve the nervous system, are usually progressive, and often cause significant disability and premature death. The term 'mitochondrial disorders' usually refers to primary disorders of the mitochondrial respiratory chain (Pfeffer et al. 2012). Secondary mitochondrial disorders such as Friedreich's ataxia will not be discussed in this evidence summary.

Mitochondrial disorders mainly affect tissues dependent upon oxidative metabolism, including the central nervous system, peripheral nerves, the eye, skeletal and endocrine muscle, and endocrine organs. Many people with mitochondrial disease have a multi-system disorder that often involves skeletal muscle and the central nervous system, although some people may have a disorder that only affects 1 organ system. Specific mitochondrial disease conditions include Alpers disease, Leigh syndrome, Leber's hereditary optic neuropathy (LHON), mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), myoclonic epilepsy with ragged-red fibres (MERRF), neurogenic weakness with ataxia and retinitis pigmentosa (NARP) and mitochondrial neuro-gastrointestinal encephalopathy (MNGIE) (Pfeffer et al. 2012).

There is currently no established treatment for mitochondrial disorders and the clinical management is largely supportive. Interventions used to modify the disease process include dietary modification, pharmacological agents and a variety of nutritional supplements such as co-enzyme Q10, thiamine, vitamin C and vitamin E and exercise therapy (Pfeffer et al. 2012).