What are the other Names for this Condition? (Also known as/Synonyms)

• MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes)
• MELAS Syndrome
• Myopathy, Mitochondrial-Encephalopathy-Lactic Acidosis-Stroke

What is Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes? (Definition/Background Information)

• Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes (MELAS) affects many parts of the body, particularly the brain and nervous system (encephalo-) and muscles (myopathy)
• Symptoms typically begin in childhood and may include muscle weakness and pain, recurrent headaches, loss of appetite, vomiting, and seizures. Most affected individuals experience stroke-like episodes beginning before age 40
• People with Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes can also have a buildup of lactic acid in their bodies that can lead to vomiting, abdominal pain, fatigue, muscle weakness, and difficulty breathing
• The genes associated with MELAS are located in mitochondrial DNA and therefore follow a maternal inheritance pattern (also called mitochondrial inheritance)
• Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes can be inherited from the mother only, because only females pass mitochondrial DNA to their children. In some cases, MELAS results from a new mutation that was not inherited from a person's mother

(Source: Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes? (Age and Sex Distribution)

• Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes is a rare disorder, with an unknown prevalence
• The onset of symptoms typically occurs in childhood, but may also begin in adolescence or adulthood (typically before the individual reaches the age of 40 years)
• Both males and females may be affected

What are the Risk Factors for Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes? (Predisposing Factors)

• A positive family history may be an important risk factor, since Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes is an inherited condition
• Currently, no other risk factors have been clearly identified for this disorder

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes? (Etiology)

• Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes is caused by mutations in mitochondrial DNA (mtDNA) and is therefore transmitted by maternal inheritance (also called mitochondrial inheritance)
• In most cases, people with MELAS inherit an altered mitochondrial gene from their mother. Only egg cells (not sperm cells) contribute mitochondria to offspring, so only females can pass on mitochondrial mutations to their children
• Less commonly, the condition results from a new mutation in a mitochondrial gene and occurs in an individual with no history of MELAS in the family

(Source: Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

What are the Signs and Symptoms of Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes?

The signs and symptoms of Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes may vary in type and severity, and include:

• Bilateral sensorineural hearing impairment 
• Congenital cataract 
• Cortical visual impairment 
• Dementia
• Diabetes mellitus 
• Encephalopathy 
• Episodic vomiting 
• Growth abnormality
• Hemiparesis 
• Left ventricular hypertrophy 
• Myopathy
• Ophthalmoplegia
• Progressive sensorineural hearing impairment 
• Variable expressivity

Based on the frequency of symptoms observed, the following information may be noted:

Very frequently present symptoms in 80-99% of the cases:

• Abnormality of mitochondrial metabolism 
• Cerebral ischemia
• Developmental regression
• Elevated serum creatine phosphokinase
• EMG abnormality 
• Fatigue 
• Generalized tonic-clonic seizures
• Increased serum lactate 
• Lactic acidosis
• Migraine
• Mitochondrial myopathy 
• Muscle weakness
• Ragged-red muscle fibers

Frequently present symptoms in 30-79% of the cases:

• Abdominal pain
• Anorexia 
• Anxiety 
• Aplasia/hypoplasia of the cerebellum
• Ataxia 
• Attention deficit hyperactivity disorder
• Cachexia
• Cerebral calcification 
• Cerebral cortical atrophy 
• Clonus 
• Decreased nerve conduction velocity 
• Depressivity
• Hallucinations
• Hemianopia 
• Memory impairment
• Nausea and vomiting 
• Pancreatitis
• Ptosis
• Reduced consciousness/confusion
• Respiratory insufficiency
• Sensorineural hearing impairment 
• Short stature
• Type II diabetes mellitus

Occasionally present symptoms in 5-29% of the cases:

• Abnormal macular morphology 
• Abnormality of neuronal migration 
• Abnormality of retinal pigmentation 
• Abnormality of visual evoked potentials 
• Amaurosis fugax 
• Anterior hypopituitarism 
• Aortic dilatation 
• Aortic dissection 
• Aphasia
• Apnea 
• Arthrogryposis multiplex congenita 
• Autism  
• Carious teeth
• Cataract
• Congestive heart failure 
• Constipation 
• Delayed puberty
• Delayed skeletal maturation
• Dysarthria
• Dystonia 
• EEG abnormality 
• Feeding difficulties in infancy 
• Fever 
• Gastroparesis
• Generalized hirsutism 
• Gingival overgrowth
• Glomerulopathy
• Goiter 
• Heart block 
• Hypercalciuria
• Hypertelorism
• Hypertension 
• Hyperthyroidism
• Hypertrophic cardiomyopathy
• Hypoparathyroidism 
• Hypopigmented skin patches 
• Hypothyroidism
• Ichthyosis 
• Intestinal obstruction
• Malabsorption
• Mask-like facies
• Microcephaly
• Multiple lipomas 
• Muscular hypotonia 
• Myalgia 
• Nephrotic syndrome 
• Nyctalopia
• Ophthalmoparesis 
• Optic atrophy 
• Paresthesia
• Primary adrenal insufficiency 
• Proteinuria
• Protruding ear
• Psychotic episodes 
• Pulmonary arterial hypertension 
• Pulmonary embolism 
• Reduced tendon reflexes
• Renal insufficiency
• Skeletal muscle atrophy
• Spontaneous hematomas 
• Stroke-like episode
• Sudden cardiac death
• Thyroiditis
• Tremor
• Tubulointerstitial abnormality
• Type I diabetes mellitus
• Ventriculomegaly
• Visual impairment
• Wolff-Parkinson-White syndrome

(Source: Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes Diagnosed?

Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes?

The complications of Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes may include:

• Risk of falls and injury due to seizures
• Severe malnutrition
• Severely restricted mobility
• Blindness
• Hearing loss
• Reduced quality of life

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes Treated?

There is no cure for Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develops.

How can Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes be Prevented?

Currently, Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes may not be preventable, since it is a genetic disorder.

• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes? (Outcomes/Resolutions)

• The prognosis of Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes is dependent upon the severity of the signs and symptoms and associated complications, if any
• It is possible for affected individuals to become bed-ridden, leading to a poor quality of life
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes:

• Mitochondrial Encephalomyopathy Lactic Acidosis and Stroke-like Episodes may be also known as Myopathy, Mitochondrial-Encephalopathy-Lactic Acidosis-Stroke

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/