About melas syndrome

What is melas syndrome?

MELAS is a rare form of dementia. MELAS is an abbreviation that stands for Mitochondrial Encephalopathy, Lactic acidosis, and Stroke-like episodes.

What are the symptoms for melas syndrome?

Symptoms of MELAS syndrome usually begin between the ages of two and fifteen years, but delayed onset cases have also been reported between fifteen and forty years and late onset cases after forty years. In approximately 75 percent of cases, onset of the disorder is before the age of 20 years. Symptoms and physical findings associated with MELAS syndrome vary greatly between affected individuals in the same family and between different families. The distinguishing feature in MELAS syndrome is the recurrence of stroke-like episodes. It is currently thought that the deficiency of a compound called nitric oxide in the small blood vessels of the brain may be responsible for the stroke-like episodes. Short stature and Hearing loss may be present and Fatigue and difficulty tolerating exercise may be early symptoms.

People with MELAS syndrome have an accumulation of lactic acid in the blood (lactic acidosis), that can lead to vomiting, abdominal pain, fatigue, Muscle Weakness and difficulty breathing. This accumulation of lactic acid has also been noted in the spinal fluid and in the brain. In some cases, affected individuals will experience a slow deterioration of intellectual function (dementia), and/or a diminished ability to communicate by speech, writing, and/or signs (aphasia). Individuals with MELAS syndrome may also have episodes of confusion and hallucinations often due to a preceding Fever (febrile illness) and/or headache. Less common symptoms include Involuntary Muscle Spasms (myoclonus), impaired muscle coordination (ataxia), cardiomyopathy, diabetes mellitus, depression, bipolar disorder, Gastrointestinal problems and kidney problems.

What are the causes for melas syndrome?

MELAS is caused by mutations in mitochondrial DNA (mtDNA). Mutations affecting the genes for mtDNA are inherited from the mother. MtDNA that is found in sperm cells is typically lost during fertilization and as a result, all human mtDNA comes from the mother. An affected mother will pass on the mutation to all her children, but only her daughters will pass on the mutation to their children. Mitochondria, which are found by the hundreds or thousands in the cells of the body, particularly in muscle and nerve tissue, carry the blueprints for regulating energy production.

Both normal and mutated mtDNA can exist in the same cell, a situation known as heteroplasmy. The number of defective mitochondria may be out-numbered by the number of normal mitochondria. Symptoms may not appear in any given generation until the mutation affects a significant proportion of mtDNA. The uneven distribution of normal and mutant mtDNA in different tissues can affect different organs in members of the same family. This can result in a variety of symptoms in affected family members.

Mutations in the mtDNA gene MT-TL1 are associated with MELAS in approximately 80% of cases. Mutations in MT-TQ, MT-TH, MT-TK, MT-TS1, MT-ND1, MT-ND5, MT-ND6, and MT-TS2 have also been associated with MELAS syndrome.

Some cases of MELAS syndrome appear to occur as the result of a new spontaneous mutation in a mitochondrial gene and are not inherited.

In addition, mutations in a nuclear gene (POLG1) have been associated with MELAS syndrome in one case.

What are the treatments for melas syndrome?

There is no known treatment for the underlying disease, which is progressive and fatal. Patients are managed according to what areas of the body are affected at a particular time. antioxidants and vitamins have been used, but there have been no consistent successes reported.

 

What are the risk factors for melas syndrome?

MELAS syndrome is a rare disorder that affects males and females in equal numbers. Although rare, MELAS syndrome is probably the most common type of mitochondrial myopathy caused by mutations in mtDNA. Some researchers believe that mitochondrial myopathies may go unrecognized and underdiagnosed in the general population, making it difficult to determine the true frequency of disorders like MELAS syndrome.

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