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Mitochondrial complex 4 deficiency, nuclear type 20(MC4DN20)

MedGen UID:
1771040
Concept ID:
C5436726
Disease or Syndrome
Synonym: MITOCHONDRIAL COMPLEX IV DEFICIENCY, NUCLEAR TYPE 20
 
Gene (location): COX5A (15q24.2)
 
Monarch Initiative: MONDO:0033655
OMIM®: 619064

Definition

Mitochondrial complex IV deficiency nuclear type 20 (MC4DN20) is an autosomal recessive multisystem metabolic disorder characterized by the onset of symptoms in infancy. Affected individuals show hypotonia, failure to thrive, and global developmental delay. Additional features include elevated liver enzymes, increased serum lactate, metabolic acidosis, and pulmonary arterial hypertension (PAH), which may result in cardiorespiratory failure and early death. Patient tissues show variably decreased levels and activity of mitochondrial respiratory complex IV (Baertling et al., 2017). For a discussion of genetic heterogeneity of mitochondrial complex IV (cytochrome c oxidase) deficiency, see 220110. [from OMIM]

Clinical features

From HPO
Cardiomegaly
MedGen UID:
5459
Concept ID:
C0018800
Finding
Increased size of the heart, clinically defined as an increased transverse diameter of the cardiac silhouette that is greater than or equal to 50% of the transverse diameter of the chest (increased cardiothoracic ratio) on a posterior-anterior projection of a chest radiograph or a computed tomography.
Pulmonary arterial hypertension
MedGen UID:
425404
Concept ID:
C2973725
Disease or Syndrome
Pulmonary hypertension is defined mean pulmonary artery pressure of 25mmHg or more and pulmonary capillary wedge pressure of 15mmHg or less when measured by right heart catheterisation at rest and in a supine position.
Failure to thrive in infancy
MedGen UID:
358083
Concept ID:
C1867873
Finding
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.
Brisk reflexes
MedGen UID:
382164
Concept ID:
C2673700
Finding
Tendon reflexes that are noticeably more active than usual (conventionally denoted 3+ on clinical examination). Brisk reflexes may or may not indicate a neurological lesion. They are distinguished from hyperreflexia by the fact that hyerreflexia is characterized by hyperactive repeating (clonic) reflexes, which are considered to be always abnormal.
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.
Frontal bossing
MedGen UID:
67453
Concept ID:
C0221354
Congenital Abnormality
Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline.
Wide anterior fontanel
MedGen UID:
400926
Concept ID:
C1866134
Finding
Enlargement of the anterior fontanelle with respect to age-dependent norms.
Elevated circulating hepatic transaminase concentration
MedGen UID:
116013
Concept ID:
C0235996
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.
Hyperprolinemia
MedGen UID:
75690
Concept ID:
C0268528
Disease or Syndrome
An increased concentration of proline in the blood.
Hyper-beta-alaninemia
MedGen UID:
75702
Concept ID:
C0268630
Disease or Syndrome
An increased concentration of alanine in the blood.
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).
Synophrys
MedGen UID:
98132
Concept ID:
C0431447
Congenital Abnormality
Meeting of the medial eyebrows in the midline.
Long eyelashes
MedGen UID:
342955
Concept ID:
C1853738
Finding
Mid upper eyelash length >10 mm or increased length of the eyelashes (subjective).
Deeply set eye
MedGen UID:
473112
Concept ID:
C0423224
Finding
An eye that is more deeply recessed into the plane of the face than is typical.
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

Diagnosis

Houstek J, Klement P, Floryk D, Antonická H, Hermanská J, Kalous M, Hansíková H, Hout'ková H, Chowdhury SK, Rosipal T, Kmoch S, Stratilová L, Zeman J
Hum Mol Genet 1999 Oct;8(11):1967-74. doi: 10.1093/hmg/8.11.1967. PMID: 10484764

Prognosis

Houstek J, Klement P, Floryk D, Antonická H, Hermanská J, Kalous M, Hansíková H, Hout'ková H, Chowdhury SK, Rosipal T, Kmoch S, Stratilová L, Zeman J
Hum Mol Genet 1999 Oct;8(11):1967-74. doi: 10.1093/hmg/8.11.1967. PMID: 10484764

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