Leigh's Disease: Symptoms, Causes, Treatment
Synopsis: Leighs disease is a form of rare inherited neuro-metabolic disorder that affects a persons central nervous system. Leigh's Disease is progressive and starts in infancy between three months and two years. On rare occasions, Leigh's disease can occur in adolescents or adults. Another form of Leigh's disease is 'X-linked Leigh's disease.' It results from gene mutations that produce other substances essential for cell metabolism. The gene is only found in a person's X chromosome.
Leigh's Disease is progressive and starts in infancy between three months and two years. On rare occasions, Leigh's disease can occur in adolescents or adults. Mutations may cause the disease in mitochondrial DNA or by deficiencies of an enzyme referred to as 'Pyruvate dehydrogenase.' The disease's symptoms usually progress rapidly, with the earliest signs potentially being poor sucking ability and a loss of motor skills and head control. The symptoms can also include vomiting, loss of appetite, continuous crying, irritability, and seizure activity. As the disease progresses, the symptoms may include a lack of muscle tone, generalized weakness, as well as episodes of lactic acidosis. Lactic acidosis may impair the person's kidney and respiratory function.
The U.S. Social Security Administration (SSA) has included Leigh's Disease as a Compassionate Allowance to expedite a disability claim.
Genetic mutations in the person's mitochondrial DNA associated with Leigh's disease interfere with their energy sources that run cells in areas of their brain and play a role in their motor movements. The main function of mitochondria is converting the energy in glucose and fatty acids into a substance known as 'Adenosine triphosphate,' or ATP. The energy within ATP drives the metabolic functioning of cells. Genetic mutations in mitochondrial DNA result in a chronic lack of energy in crucial cells, affecting the person's nervous system and causing progressive degeneration of their motor functioning.
Another form of Leigh's disease is 'X-linked Leigh's disease.' It results from gene mutations that produce another group of substances important for cell metabolism. The gene is only found in a person's X chromosome. Additional names that Leigh's disease is known by include:
- Classical Leigh's Disease
- Leigh Necrotizing Encephalopathy
- Infantile Necrotizing Encephalopathy
- Subacute Necrotizing Encephalopathy
- Necrotizing Encephalomyelopathy of Leigh's
- X-Linked Infantile Necrotizing Encephalopathy
- Adult-Onset Subacute Necrotizing Encephalomyelopathy
Symptoms of Leigh's Disease
Leigh's disease is characterized by degeneration of the person's central nervous system, including their spinal cord, brain, and optic nerve. The symptoms people with the disease experience are associated with progressive neurological deterioration and can include the loss of motor skills they had previously acquired. The person can experience vomiting, a loss of appetite, irritability, and seizures. As Leigh's disease progresses, the person can also experience a lack of muscle tone, generalized weakness, and episodes of lactic acidosis, which may lead to kidney and respiratory impairments.
The symptoms of Leigh's disease commonly develop within the first year of the person's life. On rare occasions, they may develop later in childhood. Infants with the disease usually develop symptoms that include decreased muscle tone, balance or coordination difficulties, and vomiting. One of the main reasons parents seek medical attention for their child about Leigh's disease is their child is experiencing a failure to thrive and grow. The child will eventually experience seizure activity, lactic acidosis, and resulting kidney and respiratory impairments.
Some eye abnormalities are also associated with Leigh's disease. Paralysis of some or all of the person's eye muscles, referred to as 'Ophthalmoplegia,' is common in combination with degeneration of the optic nerve and pigmentary retinopathy. This disorder will eventually lead to blindness.
Due to the cell's inability to produce ATP in persons with Leigh's disease, their tissues have not replenished enough energy and usually perish. Because of this, irreversible damage may happen in cells that require more energy, such as brain cells. This leads to mental impairments and developmental delays. Several parts of the person's brain are affected by the lack of ATP and Leigh's disease, including the person's basal ganglia, which assist in the regulation of motor performance; their brain stem, which controls functions such as swallowing, breathing, hearing and seeing; and their cerebellum, which controls their ability to balance and their voluntary muscle movements.
Causes of Leigh's Disease
Several different types of genetically determined enzyme defects may cause Leigh's disease. Most people with the disease experience defects in mitochondrial energy production, such as deficiencies of an enzyme of the mitochondrial respiratory chain complex or the pyruvate dehydrogenase complex. Most of the time, Leigh's disease is inherited as an autosomal recessive trait. Mitochondrial inheritance and X-linked recessive Leigh's disease are exceptions.
A diagnosis of Leigh's disease is generally difficult because of the broad variability in clinical symptoms, as well as the variety of different genetic explanations that cause the disease. Genetic testing for specific nuclear or mitochondrial DNA mutations can be helpful. Laboratory studies can also help in achieving a diagnosis of Leigh's disease. A Muscle biopsy can help to determine if the person is experiencing an abnormality associated with their mitochondria. Because the mitochondria are responsible for energy production, if the person is experiencing a deficiency in a protein complex that plays an important function, it may be detectable.
With Leigh's disease, the deficiency can be found in one of five complexes that make up the mitochondrial respiratory system. Complex IV referred to as 'Cytochrome C oxidase (COX),' is one in which people with the disease are commonly deficient. Unfortunately, while COX deficiency is associated with Leigh's disease, it may also indicate other mitochondrial abnormalities. There are mutations found in other complexes that may cause Leigh's disease.
Treatment of Leigh's Disease
Medical science has not discovered a treatment that is effective in slowing the progression of Leigh's disease at this time. Doctors commonly administer Thiamine or vitamin B1. Sodium bicarbonate can also be prescribed to help manage lactic acidosis. Researchers are testing dichloroacetate in an attempt to establish its effectiveness in the treatment of lactic acidosis. For people with X-linked Leigh's disease, a high-fat, low-carbohydrate diet is recommended.
Because there is no cure for Leigh's disease and its progressive nature, maintaining the person's functioning for as long as possible is the main focus instead of recovery. Physical therapists often help with exercises that can assist the person in maintaining strength and range of motion. As Leigh's disease progresses, an occupational therapist can provide the person with positioning devices for their comfort.
Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursing Disability Studies. As a Nursing Assistant Thomas has assisted people from a variety of racial, religious, gender, class, and age groups by providing care for people with all forms of disabilities from Multiple Sclerosis to Parkinson's; para and quadriplegia to Spina Bifida. Explore Thomas' complete biography for comprehensive insights into his background, expertise, and accomplishments.
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Cite This Page (APA): Thomas C. Weiss. (2010, February 16). Leigh's Disease: Symptoms, Causes, Treatment. Disabled World. Retrieved February 27, 2024 from www.disabled-world.com/disability/types/leighs-disease.php
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