Leigh's Disease

Definition

Leigh syndrome is an early onset, progressive neurological disease that involves defects in the normal function of the mitochondria. The mitochondrion is a small organelle located in most cells and is responsible for producing energy for cells and tissues throughout the body.

Description

Leigh syndrome is caused by defective cellular respiration that supplies many tissues with energy. The disorder is severe and can be particularly difficult for family members, as infants are among the severely affected. Leigh syndrome is also known as necrotizing encephalopathy.

Demographics

Leigh syndrome is a very rare disease that affects different peoples relatively equally. Some studies have shown that more males are affected than females.

Causes and symptoms

In Leigh syndrome, symptoms usually develop within the first year of life; rarely, symptoms can develop during later childhood. The infant usually initially develops symptoms that include hypotonia (decreased muscle tone), vomiting, and ataxia (balance or coordination abnormalities). Overall, failure to grow and thrive is usually the primary reason parents seek medical help. Eventually, the infant experiences seizures, lactic acidosis (an excess of lactic acid, a normal product of carbohydrate metabolism, in the body), and respiratory and kidney impairment.

Various abnormalities of the eyes are also common in Leigh syndrome. Ophthalmoplegia (paralysis of some or all of the muscles of the eye) is a typical finding, along with optic atrophy (degeneration of the optic nerve) and pigmentary retinopathy, a disorder that eventually leads to blindness.

On the cellular level, persons with Leigh syndrome have an inability to produce ATP (an energy source for the cell) in the mitochondria. Tissues that are not provided with adequate energy replenishment usually die. Irreversible damage can occur first in cells requiring much energy, such as the brain, leading to mental impairments and developmental delay. Many parts of the brain are affected by the lack of ATP in Leigh disease, including the basal ganglia, which helps regulate motor performance; the brainstem, which controls the functions of breathing, swallowing, seeing, and hearing; and the cerebellum, which coordinates balance and voluntary muscle movement.

Several genetic causes explain how persons develop Leigh disease, and several genes are involved. These genes include defects found in nuclear DNA as well as the smaller, less widely known mitochondrial DNA. Genes from both genomes contribute to the normal function of the mitochondria. Mutations in genes from the nuclear and the mitochondrial DNA have both been implicated in Leigh disease.

Content licensed from:

Author Info: Bryan Richard Cobb PhD, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Neurological Disorders, 2005

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.