Causes of the disease

Leigh synd rome is classified as a genetic disease, where mutation within genes occurs in the mitochondria - small cell organelles involved in, among other things, respiratory chain processes. The disease is thought to be associated with around 30 mutations in mitochondrial genes, although mutations in the so-called SURF1 gene and MT-ATP6 are most commonly reported. It is not fully known what causes the mutations within the mitochondria, but it results in severe impairment of mitochondrial function and intracellular energy production. Mitochondria play a key role in the functioning of the entire organism.

The disease was first described by the British scientist Denis Archibald Leigh. It is also known as Leigh syndrome or subacute necrotising encephalomyelopathy.

Inheritance and prevalence

The inheritance of the disease can run the gamut of variants. When the mutation has occurred within the so-called nuclear DNA, the disease is inherited in an autosomal recessive manner. In the case of mitochondrial DNA mutations, the disease is transmitted exclusively by the mother, in what is then called mitochondrial inheritance. The possibility of the disease being inherited in a recessive manner, coupled to the X sex chromosome, has also been described.

The disease is classified as a rare disease, affecting 1 in 40000 live-born children.

Symptoms of the disease

The first worrying symptoms appear already in infants - they can be observed even at around 2 months of age, although cases have been described where the first symptoms of the disease appeared in teenagers. Leigh syndrome is a disease that manifests itself in disorders of the nervous system, hence among the symptoms are:

• convulsions,
• decreased muscle tone,
• ataxia,
• involuntary muscle movements.

photo: panthermedia

In addition, patients develop swallowing problems, crying fits, appetite problems, visual disturbances, cardiomyopathy, problems with normal kidney function, and metabolic acidosis may also occur.

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Diagnostics

Genetic testing can confirm one hundred per cent whether one has Leigh syndrome. This type of testing is usually preceded by a number of other tests to rule out other disease entities that may give similar symptoms (e.g. encephalitis, Wilson's disease).

Prognosis and treatment

Genetic diseases are unfortunately not curable. Leigh syndrome progresses very quickly, with few patients living into their teenage years. Treatment is based on alleviating co-morbid syndromes to improve the patient's quality of life and daily functioning.