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Juvenile myopathy, encephalopathy, lactic acidosis AND stroke(MELAS)

MedGen UID:
56485
Concept ID:
C0162671
Disease or Syndrome
Synonyms: MELAS; MELAS syndrome; Mitochondrial encephalomyopathy lactic acidosis and stroke-like episodes
SNOMED CT: Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (39925003); Juvenile myopathy, encephalopathy, lactic acidosis, stroke (39925003); MELAS - mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (39925003)
Modes of inheritance:
Mitochondrial inheritance
MedGen UID:
165802
Concept ID:
C0887941
Genetic Function
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on the mitochondrial genome. Because the mitochondrial genome is essentially always maternally inherited, a mitochondrial condition can only be transmitted by females, although the condition can affect both sexes. The proportion of mutant mitochondria can vary (heteroplasmy).
Not genetically inherited
MedGen UID:
988794
Concept ID:
CN307044
Finding
Source: Orphanet
clinical entity without genetic inheritance.
 
Genes (locations): MT-CO1; MT-CO2; MT-CO3; MT-CYB; MT-ND1; MT-ND5; MT-ND6; MT-TC; MT-TF; MT-TK; MT-TL1; MT-TQ; MT-TS1; MT-TS2; MT-TV; MT-TW
 
Monarch Initiative: MONDO:0010789
OMIM®: 540000
Orphanet: ORPHA550

Definition

MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) is a multisystem disorder with protean manifestations. The vast majority of affected individuals develop signs and symptoms of MELAS between ages two and 40 years. Common clinical manifestations include stroke-like episodes, encephalopathy with seizures and/or dementia, muscle weakness and exercise intolerance, normal early psychomotor development, recurrent headaches, recurrent vomiting, hearing impairment, peripheral neuropathy, learning disability, and short stature. During the stroke-like episodes neuroimaging shows increased T2-weighted signal areas that do not correspond to the classic vascular distribution (hence the term "stroke-like"). Lactic acidemia is very common and muscle biopsies typically show ragged red fibers. [from GeneReviews]

Additional descriptions

From OMIM
MELAS syndrome, comprising mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes, is a genetically heterogeneous mitochondrial disorder with a variable clinical phenotype. The disorder is accompanied by features of central nervous system involvement, including seizures, hemiparesis, hemianopsia, cortical blindness, and episodic vomiting (Pavlakis et al., 1984; Montagna et al., 1988). Other mitochondrial encephalomyopathies include Leigh syndrome (LS; 256000), Kearns-Sayre syndrome (KSS; 530000), MERRF syndrome (545000), and Leber optic atrophy (535000).  http://www.omim.org/entry/540000
From MedlinePlus Genetics
Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) is a condition that affects many of the body's systems, particularly the brain and nervous system (encephalo-) and muscles (myopathy). The signs and symptoms of this disorder most often appear in childhood following a period of normal development, although they can begin at any age. Early symptoms 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. These episodes often involve temporary muscle weakness on one side of the body (hemiparesis), altered consciousness, vision abnormalities, seizures, and severe headaches resembling migraines. Repeated stroke-like episodes can progressively damage the brain, leading to vision loss, problems with movement, and a loss of intellectual function (dementia).

Most people with MELAS have a buildup of lactic acid in their bodies, a condition called lactic acidosis. Increased acidity in the blood can lead to vomiting, abdominal pain, extreme tiredness (fatigue), muscle weakness, and difficulty breathing. Less commonly, people with MELAS may experience involuntary muscle spasms (myoclonus), impaired muscle coordination (ataxia), hearing loss, heart and kidney problems, diabetes, and hormonal imbalances.  https://medlineplus.gov/genetics/condition/mitochondrial-encephalomyopathy-lactic-acidosis-and-stroke-like-episodes

Clinical features

From HPO
Cardiac arrhythmia
MedGen UID:
2039
Concept ID:
C0003811
Finding
Any cardiac rhythm other than the normal sinus rhythm. Such a rhythm may be either of sinus or ectopic origin and either regular or irregular. An arrhythmia may be due to a disturbance in impulse formation or conduction or both.
Congestive heart failure
MedGen UID:
9169
Concept ID:
C0018802
Disease or Syndrome
The presence of an abnormality of cardiac function that is responsible for the failure of the heart to pump blood at a rate that is commensurate with the needs of the tissues or a state in which abnormally elevated filling pressures are required for the heart to do so. Heart failure is frequently related to a defect in myocardial contraction.
Hypertensive disorder
MedGen UID:
6969
Concept ID:
C0020538
Disease or Syndrome
The presence of chronic increased pressure in the systemic arterial system.
Wolff-Parkinson-White pattern
MedGen UID:
12162
Concept ID:
C0043202
Disease or Syndrome
Wolff-Parkinson-White syndrome is a condition characterized by abnormal electrical pathways in the heart that cause a disruption of the heart's normal rhythm (arrhythmia).\n\nThe heartbeat is controlled by electrical signals that move through the heart in a highly coordinated way. A specialized cluster of cells called the atrioventricular node conducts electrical impulses from the heart's upper chambers (the atria) to the lower chambers (the ventricles). Impulses move through the atrioventricular node during each heartbeat, stimulating the ventricles to contract slightly later than the atria.\n\nPeople with Wolff-Parkinson-White syndrome are born with an extra connection in the heart, called an accessory pathway, that allows electrical signals to bypass the atrioventricular node and move from the atria to the ventricles faster than usual. The accessory pathway may also transmit electrical impulses abnormally from the ventricles back to the atria. This extra connection can disrupt the coordinated movement of electrical signals through the heart, leading to an abnormally fast heartbeat (tachycardia) and other changes in heart rhythm. Resulting symptoms include dizziness, a sensation of fluttering or pounding in the chest (palpitations), shortness of breath, and fainting (syncope). In rare cases, arrhythmias associated with Wolff-Parkinson-White syndrome can lead to cardiac arrest and sudden death. The most common arrhythmia associated with Wolff-Parkinson-White syndrome is called paroxysmal supraventricular tachycardia.\n\nComplications of Wolff-Parkinson-White syndrome can occur at any age, although some individuals born with an accessory pathway in the heart never experience any health problems associated with the condition.\n\nWolff-Parkinson-White syndrome often occurs with other structural abnormalities of the heart or underlying heart disease. The most common heart defect associated with the condition is Ebstein anomaly, which affects the valve that allows blood to flow from the right atrium to the right ventricle (the tricuspid valve). Additionally, the heart rhythm problems associated with Wolff-Parkinson-White syndrome can be a component of several other genetic syndromes, including hypokalemic periodic paralysis (a condition that causes episodes of extreme muscle weakness), Pompe disease (a disorder characterized by the storage of excess glycogen), Danon disease (a condition that weakens the heart and skeletal muscles and causes intellectual disability), and tuberous sclerosis complex (a condition that results in the growth of noncancerous tumors in many parts of the body).
Left ventricular hypertrophy
MedGen UID:
57442
Concept ID:
C0149721
Disease or Syndrome
Enlargement or increased size of the heart left ventricle.
Abnormal left ventricular function
MedGen UID:
69237
Concept ID:
C0242698
Pathologic Function
Inability of the left ventricle to perform its normal physiologic function. Failure is either due to an inability to contract the left ventricle or the inability to relax completely and fill with blood during diastole.
Stroke-like episode
MedGen UID:
346558
Concept ID:
C1857287
Finding
No consensus exists on what a stroke-like episode is, but these episodes can be functionally defined as a new neurological deficit, occurring with or without the context of seizures, which last longer than 24 hours.
Growth abnormality
MedGen UID:
808205
Concept ID:
C0262361
Finding
Episodic vomiting
MedGen UID:
333228
Concept ID:
C1838993
Finding
Paroxysmal, recurrent episodes of vomiting.
Bilateral sensorineural hearing impairment
MedGen UID:
96788
Concept ID:
C0452138
Disease or Syndrome
A bilateral form of sensorineural hearing impairment.
Progressive sensorineural hearing impairment
MedGen UID:
335894
Concept ID:
C1843156
Disease or Syndrome
A progressive form of sensorineural hearing impairment.
Hemiparesis
MedGen UID:
6783
Concept ID:
C0018989
Finding
Loss of strength in the arm, leg, and sometimes face on one side of the body. Hemiplegia refers to a complete loss of strength, whereas hemiparesis refers to an incomplete loss of strength.
Encephalopathy
MedGen UID:
39314
Concept ID:
C0085584
Disease or Syndrome
Encephalopathy is a term that means brain disease, damage, or malfunction. In general, encephalopathy is manifested by an altered mental state.
Migraine
MedGen UID:
57451
Concept ID:
C0149931
Disease or Syndrome
Migraine is a chronic neurological disorder characterized by episodic attacks of headache and associated symptoms.
Bilateral tonic-clonic seizure
MedGen UID:
141670
Concept ID:
C0494475
Sign or Symptom
A bilateral tonic-clonic seizure is a seizure defined by a tonic (bilateral increased tone, lasting seconds to minutes) and then a clonic (bilateral sustained rhythmic jerking) phase.
Dementia
MedGen UID:
99229
Concept ID:
C0497327
Mental or Behavioral Dysfunction
A loss of global cognitive ability of sufficient amount to interfere with normal social or occupational function. Dementia represents a loss of previously present cognitive abilities, generally in adults, and can affect memory, thinking, language, judgment, and behavior.
Myopathy
MedGen UID:
10135
Concept ID:
C0026848
Disease or Syndrome
A disorder of muscle unrelated to impairment of innervation or neuromuscular junction.
Inborn mitochondrial myopathy
MedGen UID:
56484
Concept ID:
C0162670
Disease or Syndrome
A type of myopathy associated with mitochondrial disease and characterized by findings on biopsy such as ragged red muscle fibers.
Ragged-red muscle fibers
MedGen UID:
477048
Concept ID:
C3275417
Finding
An abnormal appearance of muscle fibers observed on muscle biopsy. Ragged red fibers can be visualized with Gomori trichrome staining as irregular and intensely red subsarcolemmal zones, whereas the normal myofibrils are green. The margins of affect fibers appear red and ragged. The ragged-red is due to the accumulation of abnormal mitochondria below the plasma membrane of the muscle fiber, leading to the appearance of a red rim and speckled sarcoplasm.
Lactic acidosis
MedGen UID:
1717
Concept ID:
C0001125
Disease or Syndrome
An abnormal buildup of lactic acid in the body, leading to acidification of the blood and other bodily fluids.
Diabetes mellitus
MedGen UID:
8350
Concept ID:
C0011849
Disease or Syndrome
A group of abnormalities characterized by hyperglycemia and glucose intolerance.
Developmental cataract
MedGen UID:
3202
Concept ID:
C0009691
Congenital Abnormality
A cataract that occurs congenitally as the result of a developmental defect, in contrast to the majority of cataracts that occur in adulthood as the result of degenerative changes of the lens.
Hemianopia
MedGen UID:
9193
Concept ID:
C0018979
Finding
Partial or complete loss of vision in one half of the visual field of one or both eyes.
Ophthalmoplegia
MedGen UID:
45205
Concept ID:
C0029089
Sign or Symptom
Paralysis of one or more extraocular muscles that are responsible for eye movements.
Cerebral visual impairment
MedGen UID:
890568
Concept ID:
C4048268
Pathologic Function
A form of loss of vision caused by damage to the visual cortex rather than a defect in the eye.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVJuvenile myopathy, encephalopathy, lactic acidosis AND stroke
Follow this link to review classifications for Juvenile myopathy, encephalopathy, lactic acidosis AND stroke in Orphanet.

Professional guidelines

PubMed

Barcelos I, Shadiack E, Ganetzky RD, Falk MJ
Curr Opin Pediatr 2020 Dec;32(6):707-718. doi: 10.1097/MOP.0000000000000954. PMID: 33105273Free PMC Article
El-Hattab AW, Adesina AM, Jones J, Scaglia F
Mol Genet Metab 2015 Sep-Oct;116(1-2):4-12. Epub 2015 Jun 15 doi: 10.1016/j.ymgme.2015.06.004. PMID: 26095523
Karaa A, Goldstein A
Pediatr Diabetes 2015 Feb;16(1):1-9. Epub 2014 Oct 20 doi: 10.1111/pedi.12223. PMID: 25330715

Recent clinical studies

Etiology

Yatsuga S, Povalko N, Nishioka J, Katayama K, Kakimoto N, Matsuishi T, Kakuma T, Koga Y; Taro Matsuoka for MELAS Study Group in Japan
Biochim Biophys Acta 2012 May;1820(5):619-24. Epub 2011 Apr 2 doi: 10.1016/j.bbagen.2011.03.015. PMID: 21443929

Diagnosis

Caldarazzo Ienco E, Orsucci D, Simoncini C, Montano V, LoGerfo A, Siciliano G, Bonuccelli U, Mancuso M
Mitochondrion 2016 Sep;30:148-50. Epub 2016 Jul 21 doi: 10.1016/j.mito.2016.07.008. PMID: 27453332
Yatsuga S, Povalko N, Nishioka J, Katayama K, Kakimoto N, Matsuishi T, Kakuma T, Koga Y; Taro Matsuoka for MELAS Study Group in Japan
Biochim Biophys Acta 2012 May;1820(5):619-24. Epub 2011 Apr 2 doi: 10.1016/j.bbagen.2011.03.015. PMID: 21443929
Stenqvist L, Paetau A, Valanne L, Suomalainen A, Pihko H
Pediatr Res 2005 Aug;58(2):258-62. Epub 2005 Jul 8 doi: 10.1203/01.PDR.0000169966.82325.1A. PMID: 16006433

Therapy

Yatsuga S, Povalko N, Nishioka J, Katayama K, Kakimoto N, Matsuishi T, Kakuma T, Koga Y; Taro Matsuoka for MELAS Study Group in Japan
Biochim Biophys Acta 2012 May;1820(5):619-24. Epub 2011 Apr 2 doi: 10.1016/j.bbagen.2011.03.015. PMID: 21443929

Prognosis

Dvorakova V, Kolarova H, Magner M, Tesarova M, Hansikova H, Zeman J, Honzik T
Mol Genet Metab 2016 Aug;118(4):288-95. Epub 2016 Jun 6 doi: 10.1016/j.ymgme.2016.06.003. PMID: 27296531
Yatsuga S, Povalko N, Nishioka J, Katayama K, Kakimoto N, Matsuishi T, Kakuma T, Koga Y; Taro Matsuoka for MELAS Study Group in Japan
Biochim Biophys Acta 2012 May;1820(5):619-24. Epub 2011 Apr 2 doi: 10.1016/j.bbagen.2011.03.015. PMID: 21443929

Clinical prediction guides

Dvorakova V, Kolarova H, Magner M, Tesarova M, Hansikova H, Zeman J, Honzik T
Mol Genet Metab 2016 Aug;118(4):288-95. Epub 2016 Jun 6 doi: 10.1016/j.ymgme.2016.06.003. PMID: 27296531
Yatsuga S, Povalko N, Nishioka J, Katayama K, Kakimoto N, Matsuishi T, Kakuma T, Koga Y; Taro Matsuoka for MELAS Study Group in Japan
Biochim Biophys Acta 2012 May;1820(5):619-24. Epub 2011 Apr 2 doi: 10.1016/j.bbagen.2011.03.015. PMID: 21443929

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