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Melas Syndrome

What is Melas Syndrome?

Melas Syndrome is used as an acronym, which can be illustrated as:

M – Mitochondrial myopathy,
E – Encephalopathy,
L A – Lactic acidosis
S – Stroke

The above mentioned cluster of conditions develops and gradually progress due to neurodegenerative condition. MELAS syndrome has wide range of sign and symptoms and may sporadically or maternal pedigrees are involved in MELAS syndrome.

Generally the symptoms appear at childhood age without interfering normal growth. However, the disease condition can be occurred and progressed at any age. But it has been noticed that before 40 years of age, stroke-like episodes usually experienced.

MELAS syndrome is not restricted with the above mentioned clinical presentations, but neuropsychiatric dysfunctions, seizures attack, hearing loss, endocrinopathies, cardiac disease, diabetes mellitus, exercise intolerance, vision loss are included prominent features^1,2.

Melas Syndrome Picture 3

Symptoms

Usually commencement of the symptoms occur at the age between two years to fifteen years. The age of fifteen and forty years is considered as delayed onset of symptoms, whereas the late symptoms are occurred after forty years of age. However, almost in 75 percent of cases, the onset of symptoms occur before 20 years of age.
The symptoms of MELAS syndrome is not uniform for all the cases, they vary from individual to individual; family to family. The main distinguishing factor for MELAS syndrome varies from stroke-like episodes. It is assumed that deficiency of nitric oxide in the blood vessels of the brain cause stroke-like episodes.
The included early symptoms are short physical structure, loss of hearing, fatigue and difficulty tolerating exercise.
Abdominal pain, vomiting, muscle weakness, persistent fatigue condition, breathing difficulty are several symptoms associated due to lactic acidosis. Lactic acidosis is the condition in which lactic acid accumulated into the blood. In some cases, lactic acids are accumulated in the central nervous system, including spinal fluid and brain.
In some cases, gradual intellectual function deterioration leads to dementia, difficulty in speech and writing. Even some patient unable to understand speech (aphasia).
Confusion, hallucination, persisting fever and headache can occur in some patients.
In rare cases, myoclonus (spasm in involuntary muscle), ataxia (body balancing difficulty due to impaired muscle coordination), depression, diabetes mellitus, gastrointestinal problems, kidney problems and bipolar disorder are also observed^1,2,3.

Cause

Mitochondrial DNA mutation is the primary cause of MELAS Syndrome. The mtDNA (mitochondrial DNA) gene mutation usually inherited from the maternal source. The affected mother can acts as a carrier and pass the defective mutation of the mitochondrial DNA to all her children.

but girl child can again acts as carrier and forward the mutations in mitochondrial DNA to the next generation. The mitochondria present in muscles and nervous tissue, which are main source of regulating energy usually get affected.

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. In MELAS Syndrome, both Both normal and mutated mitochondrial DNA co-exist and the condition is known as heteroplasmy.

The affected family can got the prominent symptoms appearance at any generation depending upon the number of mtDNA affected. The symptoms varies in the same family member, because the heteroplasmy proportion varies in organ and that provides according symptoms.

In 80 percent of cases, identified responsible gene mutation is mtDNA gene MT-TL1. Other involves gene mutation are MT-TH, MT-TK, MT-TQ, MT-TS1, MT-TS2. MT-ND1, MT-ND5, and MT-ND6. In some cases, spontaneously without involvement of inherited mitochondrial gene mutation also involve. Yet now POLG1(nuclear gene mutation) gene involvement is observed in one case^2,3.

Diagnosis

Detail analysis of clinical findings and genetic testing are involved in MELAS Syndrome.

Clinical testing showed elevation of lactate and pyruvate concentrations in MELAS syndrome.. CSF protein concentration is also high in MELAS syndrome.
Magnetic resonance imaging (MRI) is also conducted for brain imaging to detect stroke-like lesions.
Magnetic resonance spectroscopy (MRS) is applied to detect elevated level of lactate in the brain.
Heart rhythm abnormality is diagnosed through electrocardiogram
Cardiomyopathy may be detected through echocardiogram.
Biopsy of muscle sample will usually detect torn red fibers.
White blood cells analysis can show the findings of mtDNA mutations, but skin, hair follicles, urinary sediment and skeletal muscle sample also tested due to presence of heteroplasmy.
Urinary sediment testing also assist to detect mutation^2,3.

Melas Syndrome Picture 2

Treatment

There is no specific therapy available for MELAS syndrome treatment.

Anti-convulsant drugs excluding Valproic acid are used as preventive therapy to control seizures attacks associated with MELAS syndrome.
Sensorineural deafness can be treated by cochlear implants.
Coenzyme q10, L-carnitine and other energy enhancers used to give for increasing energy production in the mitochondria
Moderate treadmill training may suggested to improve aerobic capacity and fall of resting lactate levels in patients with mitochondrial myopathies
L-arginine can be intravenously administered to treat the acute stroke-like episodes
arginine Oral therapy is prescrived as preventive therapy for recurrence of stroke-like episodes.
Genetic counseling is optional for patients and their family members.^{2, 3}

Life Expectancy

The estimated current calculated life expectancy for Melas Syndrome affected individuals is almost five years.⁴

References

mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes; Genetic Home Reference; Retrieve from https://ghr.nlm.nih.gov/condition/mitochondrial-encephalomyopathy-lactic-acidosis-and-stroke-like-episodes
MELAS Syndrome; National Organization For Rare Disease; Retrieve from https://rarediseases.org/rare-diseases/melas-syndrome/
William C. Shiel . MELAS Syndrome; Retrieve from http://www.medicinenet.com/melas_syndrome/article.html
MELAS Syndrome; Syndrome; Retrieve from http://syndrome.org/melas-syndrome/