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Myopathy, lactic acidosis, and sideroblastic anemia 2(MLASA2)

MedGen UID:
462152
Concept ID:
C3150802
Disease or Syndrome
Synonym: MLASA2
 
Gene (location): YARS2 (12p11.21)
 
Monarch Initiative: MONDO:0013307
OMIM®: 613561

Definition

Myopathy, lactic acidosis, and sideroblastic anemia-2 (MLASA2) is an autosomal recessive disorder of the mitochondrial respiratory chain. The disorder shows marked phenotypic variability: some patients have a severe multisystem disorder from infancy, including cardiomyopathy and respiratory insufficiency resulting in early death, whereas others present in the second or third decade of life with sideroblastic anemia and mild muscle weakness (summary by Riley et al., 2013). For a discussion of genetic heterogeneity of MLASA, see MLASA1 (600462). [from OMIM]

Clinical features

From HPO
Exercise intolerance
MedGen UID:
603270
Concept ID:
C0424551
Finding
A functional motor deficit where individuals whose responses to the challenges of exercise fail to achieve levels considered normal for their age and gender.
Hypertrophic cardiomyopathy
MedGen UID:
2881
Concept ID:
C0007194
Disease or Syndrome
Hypertrophic cardiomyopathy (HCM) is defined by the presence of increased ventricular wall thickness or mass in the absence of loading conditions (hypertension, valve disease) sufficient to cause the observed abnormality.
Growth delay
MedGen UID:
99124
Concept ID:
C0456070
Pathologic Function
A deficiency or slowing down of growth pre- and postnatally.
Failure to thrive
MedGen UID:
746019
Concept ID:
C2315100
Disease or Syndrome
Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.
Dysphagia
MedGen UID:
41440
Concept ID:
C0011168
Disease or Syndrome
Difficulty in swallowing.
Hepatomegaly
MedGen UID:
42428
Concept ID:
C0019209
Finding
Abnormally increased size of the liver.
Lethargy
MedGen UID:
7310
Concept ID:
C0023380
Sign or Symptom
A state of fatigue, either physical or mental slowness and sluggishness, with difficulties in initiating or performing simple tasks. Distinguished from apathy which implies indifference and a lack of desire or interest in the task. A person with lethargy may have the desire, but not the energy to engage in personal or socially relevant tasks.
Motor delay
MedGen UID:
381392
Concept ID:
C1854301
Finding
A type of Developmental delay characterized by a delay in acquiring motor skills.
Sideroblastic anemia
MedGen UID:
8067
Concept ID:
C0002896
Disease or Syndrome
Sideroblastic anemia results from a defect in the incorporation of iron into the heme molecule. A sideroblast is an erythroblast that has stainable deposits of iron in cytoplasm (this can be demonstrated by Prussian blue staining).
Hypotonia
MedGen UID:
10133
Concept ID:
C0026827
Finding
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
Muscle weakness
MedGen UID:
57735
Concept ID:
C0151786
Finding
Reduced strength of muscles.
Generalized amyotrophy
MedGen UID:
234650
Concept ID:
C1389113
Disease or Syndrome
Generalized (diffuse, unlocalized) amyotrophy (muscle atrophy) affecting multiple muscles.
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.
Cytochrome C oxidase-negative muscle fibers
MedGen UID:
867360
Concept ID:
C4021724
Finding
An abnormally reduced activity of the enzyme cytochrome C oxidase in muscle tissue.
Respiratory distress
MedGen UID:
96907
Concept ID:
C0476273
Sign or Symptom
Respiratory distress is objectively observable as the physical or emotional consequences from the experience of dyspnea. The physical presentation of respiratory distress is generally referred to as labored breathing, while the sensation of respiratory distress is called shortness of breath or dyspnea.
Respiratory insufficiency due to muscle weakness
MedGen UID:
812797
Concept ID:
C3806467
Finding
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.
Increased circulating lactate concentration
MedGen UID:
332209
Concept ID:
C1836440
Finding
Abnormally increased level of blood lactate (2-hydroxypropanoic acid). Lactate is produced from pyruvate by lactate dehydrogenase during normal metabolism. The terms lactate and lactic acid are often used interchangeably but lactate (the component measured in blood) is strictly a weak base whereas lactic acid is the corresponding acid. Lactic acidosis is often used clinically to describe elevated lactate but should be reserved for cases where there is a corresponding acidosis (pH below 7.35).
Elevated circulating hepatic transaminase concentration
MedGen UID:
338525
Concept ID:
C1848701
Finding
Elevations of the levels of SGOT and SGPT in the serum. SGOT (serum glutamic oxaloacetic transaminase) and SGPT (serum glutamic pyruvic transaminase) are transaminases primarily found in the liver and heart and are released into the bloodstream as the result of liver or heart damage. SGOT and SGPT are used clinically mainly as markers of liver damage.
Pallor
MedGen UID:
10547
Concept ID:
C0030232
Finding
Abnormally pale skin.
Ptosis
MedGen UID:
2287
Concept ID:
C0005745
Disease or Syndrome
The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective).
Nystagmus
MedGen UID:
45166
Concept ID:
C0028738
Disease or Syndrome
Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.
Strabismus
MedGen UID:
21337
Concept ID:
C0038379
Disease or Syndrome
A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error.
Decreased activity of mitochondrial complex I
MedGen UID:
393796
Concept ID:
C2677650
Finding
A reduction in the activity of the mitochondrial respiratory chain complex I, which is part of the electron transport chain in mitochondria.
Decreased activity of mitochondrial complex III
MedGen UID:
460434
Concept ID:
C3149083
Finding
A reduction in the activity of the mitochondrial respiratory chain complex III, which is part of the electron transport chain in mitochondria.
Decreased activity of mitochondrial complex IV
MedGen UID:
866520
Concept ID:
C4020800
Finding
A reduction in the activity of the mitochondrial respiratory chain complex IV, which is part of the electron transport chain in mitochondria.

Recent clinical studies

Etiology

Rudaks LI, Watson E, Oboudiyat C, Kumar KR, Sullivan P, Cowley MJ, Davis RL, Sue CM
Am J Med Genet A 2022 Jul;188(7):2226-2230. Epub 2022 Apr 8 doi: 10.1002/ajmg.a.62755. PMID: 35393742Free PMC Article
Tesarova M, Vondrackova A, Stufkova H, Veprekova L, Stranecky V, Berankova K, Hansikova H, Magner M, Galoova N, Honzik T, Vodickova E, Stary J, Zeman J
Pediatr Blood Cancer 2019 Apr;66(4):e27591. Epub 2018 Dec 26 doi: 10.1002/pbc.27591. PMID: 30588737

Diagnosis

Rudaks LI, Watson E, Oboudiyat C, Kumar KR, Sullivan P, Cowley MJ, Davis RL, Sue CM
Am J Med Genet A 2022 Jul;188(7):2226-2230. Epub 2022 Apr 8 doi: 10.1002/ajmg.a.62755. PMID: 35393742Free PMC Article
Metodiev MD, Assouline Z, Landrieu P, Chretien D, Bader-Meunier B, Guitton C, Munnich A, Rötig A
Eur J Hum Genet 2015 Jun;23(6):880-2. Epub 2014 Sep 17 doi: 10.1038/ejhg.2014.192. PMID: 25227147Free PMC Article
Finsterer J
Acta Haematol 2007;118(2):88-98. Epub 2007 Jul 18 doi: 10.1159/000105676. PMID: 17637511

Prognosis

Tesarova M, Vondrackova A, Stufkova H, Veprekova L, Stranecky V, Berankova K, Hansikova H, Magner M, Galoova N, Honzik T, Vodickova E, Stary J, Zeman J
Pediatr Blood Cancer 2019 Apr;66(4):e27591. Epub 2018 Dec 26 doi: 10.1002/pbc.27591. PMID: 30588737
Nakajima J, Eminoglu TF, Vatansever G, Nakashima M, Tsurusaki Y, Saitsu H, Kawashima H, Matsumoto N, Miyake N
J Hum Genet 2014 Apr;59(4):229-32. Epub 2014 Jan 16 doi: 10.1038/jhg.2013.143. PMID: 24430573
Finsterer J
Acta Haematol 2007;118(2):88-98. Epub 2007 Jul 18 doi: 10.1159/000105676. PMID: 17637511

Clinical prediction guides

Riley LG, Heeney MM, Rudinger-Thirion J, Frugier M, Campagna DR, Zhou R, Hale GA, Hilliard LM, Kaplan JA, Kwiatkowski JL, Sieff CA, Steensma DP, Rennings AJ, Simons A, Schaap N, Roodenburg RJ, Kleefstra T, Arenillas L, Fita-Torró J, Ahmed R, Abboud M, Bechara E, Farah R, Tamminga RYJ, Bottomley SS, Sanchez M, Huls G, Swinkels DW, Christodoulou J, Fleming MD
Haematologica 2018 Dec;103(12):2008-2015. Epub 2018 Jul 19 doi: 10.3324/haematol.2017.182659. PMID: 30026338Free PMC Article
Finsterer J
Acta Haematol 2007;118(2):88-98. Epub 2007 Jul 18 doi: 10.1159/000105676. PMID: 17637511
Inbal A, Avissar N, Shaklai M, Kuritzky A, Schejter A, Ben-David E, Shanske S, Garty BZ
Am J Med Genet 1995 Jan 30;55(3):372-8. doi: 10.1002/ajmg.1320550325. PMID: 7726239

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