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Progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 1(PEOB1)

MedGen UID:
897191
Concept ID:
C4225153
Disease or Syndrome
Synonyms: Cerebellar ataxia infantile with progressive external ophthalmoplegia; PEOB1; Progressive external ophthalmoplegia, autosomal recessive 1
 
Gene (location): POLG (15q26.1)
 
Monarch Initiative: MONDO:0009783
OMIM®: 258450

Disease characteristics

Excerpted from the GeneReview: POLG-Related Disorders
POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined before the molecular basis was known. POLG-related disorders can therefore be considered an overlapping spectrum of disease presenting from early childhood to late adulthood. The age of onset broadly correlates with the clinical phenotype. In individuals with early-onset disease (prior to age 12 years), liver involvement, feeding difficulties, seizures, hypotonia, and muscle weakness are the most common clinical features. This group has the worst prognosis. In the juvenile/adult-onset form (age 12-40 years), disease is typically characterized by peripheral neuropathy, ataxia, seizures, stroke-like episodes, and, in individuals with longer survival, progressive external ophthalmoplegia (PEO). This group generally has a better prognosis than the early-onset group. Late-onset disease (after age 40 years) is characterized by ptosis and PEO, with additional features such as peripheral neuropathy, ataxia, and muscle weakness. This group overall has the best prognosis. [from GeneReviews]
Authors:
Bruce H Cohen  |  Patrick F Chinnery  |  William C Copeland   view full author information

Additional description

From OMIM
Progressive external ophthalmoplegia (PEO) is characterized by multiple mitochondrial DNA (mtDNA) deletions in skeletal muscle. The most common clinical features include adult-onset of weakness of the external eye muscles and exercise intolerance. Additional symptoms are variable, and may include cataracts, hearing loss, sensory axonal neuropathy, ataxia, depression, hypogonadism, and parkinsonism. Less common features include mitral valve prolapse, cardiomyopathy, and gastrointestinal dysmotility. Both autosomal dominant and autosomal recessive inheritance can occur; autosomal recessive inheritance is usually more severe (Filosto et al., 2003; Luoma et al., 2004). Drachman (1975) gave a classification of disorders associated with progressive external ophthalmoplegia, which he termed 'ophthalmoplegia plus' (Drachman, 1968). Genetic Heterogeneity of Autosomal Recessive External Ophthalmoplegia with Mitochondrial DNA Deletions See also PEOB2 (616479), caused by mutation in the RNASEH1 gene (604123) on chromosome 2p25; PEOB3 (617069), caused by mutation in the TK2 gene (188250) on chromosome 16q21; PEOB4 (617070), caused by mutation in the DGUOK gene (601465) on chromosome 2p13; and PEOB5 (618098), caused by mutation in the TOP3A gene (601243) on chromosome 17p11.  http://www.omim.org/entry/258450

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.
Secondary amenorrhea
MedGen UID:
115919
Concept ID:
C0232940
Disease or Syndrome
The cessation of menstruation for six months or more in a female that is not pregnant, breastfeeding or menopausal.
Pes cavus
MedGen UID:
675590
Concept ID:
C0728829
Congenital Abnormality
An increase in height of the medial longitudinal arch of the foot that does not flatten on weight bearing (i.e., a distinctly hollow form of the sole of the foot when it is bearing weight).
Mitral regurgitation
MedGen UID:
7670
Concept ID:
C0026266
Disease or Syndrome
An abnormality of the mitral valve characterized by insufficiency or incompetence of the mitral valve resulting in retrograde leaking of blood through the mitral valve upon ventricular contraction.
Mitral valve prolapse
MedGen UID:
7671
Concept ID:
C0026267
Disease or Syndrome
One or both of the leaflets (cusps) of the mitral valve bulges back into the left atrium upon contraction of the left ventricle.
Cardiomyopathy
MedGen UID:
209232
Concept ID:
C0878544
Disease or Syndrome
A myocardial disorder in which the heart muscle is structurally and functionally abnormal, in the absence of coronary artery disease, hypertension, valvular disease and congenital heart disease sufficient to cause the observed myocardial abnormality.
Dysphagia
MedGen UID:
41440
Concept ID:
C0011168
Disease or Syndrome
Difficulty in swallowing.
Sensorineural hearing loss disorder
MedGen UID:
9164
Concept ID:
C0018784
Disease or Syndrome
A type of hearing impairment in one or both ears related to an abnormal functionality of the cochlear nerve.
Depression
MedGen UID:
4229
Concept ID:
C0011581
Mental or Behavioral Dysfunction
Frequently experiencing feelings of being down, miserable, and/or hopeless; struggling to recover from these moods; having a pessimistic outlook on the future; feeling a pervasive sense of shame; having a low self-worth; experiencing thoughts of suicide and engaging in suicidal behavior.
Dysarthria
MedGen UID:
8510
Concept ID:
C0013362
Mental or Behavioral Dysfunction
Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed.
Dystonic disorder
MedGen UID:
3940
Concept ID:
C0013421
Sign or Symptom
An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk.
Babinski sign
MedGen UID:
19708
Concept ID:
C0034935
Finding
Upturning of the big toe (and sometimes fanning of the other toes) in response to stimulation of the sole of the foot. If the Babinski sign is present it can indicate damage to the corticospinal tract.
Emotional lability
MedGen UID:
39319
Concept ID:
C0085633
Mental or Behavioral Dysfunction
Unstable emotional experiences and frequent mood changes; emotions that are easily aroused, intense, and/or disproportionate to events and circumstances.
Bradykinesia
MedGen UID:
115925
Concept ID:
C0233565
Sign or Symptom
Bradykinesia literally means slow movement, and is used clinically to denote a slowness in the execution of movement (in contrast to hypokinesia, which is used to refer to slowness in the initiation of movement).
Areflexia
MedGen UID:
115943
Concept ID:
C0234146
Finding
Absence of neurologic reflexes such as the knee-jerk reaction.
Positive Romberg sign
MedGen UID:
66017
Concept ID:
C0240914
Finding
The patient stands with the feet placed together and balance and is asked to close his or her eyes. A loss of balance upon eye closure is a positive Romberg sign and is interpreted as indicating a deficit in proprioception.
Parkinsonian disorder
MedGen UID:
66079
Concept ID:
C0242422
Disease or Syndrome
Characteristic neurologic anomaly resulting from degeneration of dopamine-generating cells in the substantia nigra, a region of the midbrain, characterized clinically by shaking, rigidity, slowness of movement and difficulty with walking and gait.
Steppage gait
MedGen UID:
98105
Concept ID:
C0427149
Finding
An abnormal gait pattern that arises from weakness of the pretibial and peroneal muscles due to a lower motor neuron lesion. Affected patients have footdrop and are unable to dorsiflex and evert the foot. The leg is lifted high on walking so that the toes clear the ground, and there may be a slapping noise when the foot strikes the ground again.
Truncal ataxia
MedGen UID:
96535
Concept ID:
C0427190
Sign or Symptom
Truncal ataxia is a sign of ataxia characterized by instability of the trunk. It usually occurs during sitting.
Hyporeflexia
MedGen UID:
195967
Concept ID:
C0700078
Finding
Reduction of neurologic reflexes such as the knee-jerk reaction.
Cerebellar atrophy
MedGen UID:
196624
Concept ID:
C0740279
Disease or Syndrome
Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.
Limb ataxia
MedGen UID:
196692
Concept ID:
C0750937
Finding
A kind of ataxia that affects movements of the extremities.
Gait ataxia
MedGen UID:
155642
Concept ID:
C0751837
Sign or Symptom
A type of ataxia characterized by the impairment of the ability to coordinate the movements required for normal walking. Gait ataxia is characteirzed by a wide-based staggering gait with a tendency to fall.
Increased CSF protein concentration
MedGen UID:
329971
Concept ID:
C1806780
Finding
Increased concentration of protein in the cerebrospinal fluid.
Sensory axonal neuropathy
MedGen UID:
334116
Concept ID:
C1842587
Finding
An axonal neuropathy of peripheral sensory nerves.
Sensory ataxic neuropathy
MedGen UID:
336060
Concept ID:
C1843859
Finding
Impaired distal vibration sensation
MedGen UID:
381262
Concept ID:
C1853767
Finding
A decrease in the ability to perceive vibration in the distal portions of the limbs.
Impaired distal proprioception
MedGen UID:
867227
Concept ID:
C4021585
Finding
A loss or impairment of the sensation of the relative position of parts of the body and joint position occurring at distal joints.
Intention tremor
MedGen UID:
1642960
Concept ID:
C4551520
Sign or Symptom
A type of kinetic tremor that occurs during target directed movement is called intention tremor. That is, an oscillatory cerebellar ataxia that tends to be absent when the limbs are inactive and during the first part of voluntary movement but worsening as the movement continues and greater precision is required (e.g., in touching a target such as the patient's nose or a physician's finger).
Rigidity
MedGen UID:
7752
Concept ID:
C0026837
Sign or Symptom
Continuous involuntary sustained muscle contraction. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from muscle spasticity.
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
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.
Proximal muscle weakness
MedGen UID:
113169
Concept ID:
C0221629
Finding
A lack of strength of the proximal muscles.
Difficulty climbing stairs
MedGen UID:
68676
Concept ID:
C0239067
Finding
Reduced ability to climb stairs.
Muscle fiber atrophy
MedGen UID:
451037
Concept ID:
C0333751
Cell or Molecular Dysfunction
Facial palsy
MedGen UID:
87660
Concept ID:
C0376175
Disease or Syndrome
Facial nerve palsy is a dysfunction of cranial nerve VII (the facial nerve) that results in inability to control facial muscles on the affected side with weakness of the muscles of facial expression and eye closure. This can either be present in unilateral or bilateral form.
Weakness of facial musculature
MedGen UID:
98103
Concept ID:
C0427055
Disease or Syndrome
Reduced strength of one or more muscles innervated by the facial nerve (the seventh cranial nerve).
Distal muscle weakness
MedGen UID:
140883
Concept ID:
C0427065
Finding
Reduced strength of the musculature of the distal extremities.
Muscular atrophy
MedGen UID:
892680
Concept ID:
C0541794
Pathologic Function
The presence of skeletal muscular atrophy (which is also known as amyotrophy).
Generalized amyotrophy
MedGen UID:
234650
Concept ID:
C1389113
Disease or Syndrome
Generalized (diffuse, unlocalized) amyotrophy (muscle atrophy) affecting multiple muscles.
Increased variability in muscle fiber diameter
MedGen UID:
336019
Concept ID:
C1843700
Finding
An abnormally high degree of muscle fiber size variation. This phenotypic feature can be observed upon muscle biopsy.
Muscle fiber necrosis
MedGen UID:
376893
Concept ID:
C1850848
Pathologic Function
Abnormal cell death involving muscle fibers usually associated with break in, or absence of, muscle surface fiber membrane and resulting in irreversible damage to 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.
Multiple mitochondrial DNA deletions
MedGen UID:
479006
Concept ID:
C3277376
Finding
The presence of multiple deletions of mitochondrial DNA (mtDNA).
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.
EMG: myopathic abnormalities
MedGen UID:
867362
Concept ID:
C4021726
Pathologic Function
The presence of abnormal electromyographic patterns indicative of myopathy, such as small-short polyphasic motor unit potentials.
Subsarcolemmal accumulations of abnormally shaped mitochondria
MedGen UID:
871128
Concept ID:
C4025597
Anatomical Abnormality
An abnormally increased number of mitochondria in the cytoplasma adjacent to the sarcolemma (muscle cell membrane), whereby the mitochondria also possess an abnormal morphology.
Respiratory insufficiency due to muscle weakness
MedGen UID:
812797
Concept ID:
C3806467
Finding
Elevated circulating creatine kinase concentration
MedGen UID:
69128
Concept ID:
C0241005
Finding
An elevation of the level of the enzyme creatine kinase (also known as creatine phosphokinase (CK; EC 2.7.3.2) in the blood. CK levels can be elevated in a number of clinical disorders such as myocardial infarction, rhabdomyolysis, and muscular dystrophy.
Mildly elevated creatine kinase
MedGen UID:
342469
Concept ID:
C1850309
Finding
Dysphonia
MedGen UID:
282893
Concept ID:
C1527344
Mental or Behavioral Dysfunction
Difficulty in speaking due to a physical disorder of the mouth, tongue, throat, or vocal cords. Associated with a known physical or neurological cause.
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).
Diplopia
MedGen UID:
41600
Concept ID:
C0012569
Disease or Syndrome
Diplopia is a condition in which a single object is perceived as two images, it is also known as double vision.
Esotropia
MedGen UID:
4550
Concept ID:
C0014877
Disease or Syndrome
A form of strabismus with one or both eyes turned inward ('crossed') to a relatively severe degree, usually defined as 10 diopters or more.
Optic atrophy
MedGen UID:
18180
Concept ID:
C0029124
Disease or Syndrome
Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy.
Progressive external ophthalmoplegia
MedGen UID:
102439
Concept ID:
C0162674
Disease or Syndrome
Progressive external ophthalmoplegia is a condition characterized by weakness of the eye muscles. The condition typically appears in adults between ages 18 and 40 and slowly worsens over time. The first sign of progressive external ophthalmoplegia is typically drooping eyelids (ptosis), which can affect one or both eyelids. As ptosis worsens, affected individuals may use the forehead muscles to try to lift the eyelids, or they may lift up their chin in order to see. Another characteristic feature of progressive external ophthalmoplegia is weakness or paralysis of the muscles that move the eye (ophthalmoplegia). Affected individuals have to turn their head to see in different directions, especially as the ophthalmoplegia worsens. People with progressive external ophthalmoplegia may also have general weakness of the muscles used for movement (myopathy), particularly those in the neck, arms, or legs. The weakness may be especially noticeable during exercise (exercise intolerance). Muscle weakness may also cause difficulty swallowing (dysphagia).\n\nWhen the muscle cells of affected individuals are stained and viewed under a microscope, these cells usually appear abnormal. These abnormal muscle cells contain an excess of cell structures called mitochondria and are known as ragged-red fibers.\n\nAlthough muscle weakness is the primary symptom of progressive external ophthalmoplegia, this condition can be accompanied by other signs and symptoms. In these instances, the condition is referred to as progressive external ophthalmoplegia plus (PEO+). Additional signs and symptoms can include hearing loss caused by nerve damage in the inner ear (sensorineural hearing loss), weakness and loss of sensation in the limbs due to nerve damage (neuropathy), impaired muscle coordination (ataxia), a pattern of movement abnormalities known as parkinsonism, and depression.\n\nProgressive external ophthalmoplegia is part of a spectrum of disorders with overlapping signs and symptoms. Similar disorders include ataxia neuropathy spectrum and Kearns-Sayre syndrome. Like progressive external ophthalmoplegia, the other conditions in this spectrum can involve weakness of the eye muscles. However, these conditions have many additional features not shared by most people with progressive external ophthalmoplegia.
Dyschromatopsia
MedGen UID:
163559
Concept ID:
C0858618
Disease or Syndrome
A form of colorblindness in which only two of the three fundamental colors can be distinguished due to a lack of one of the retinal cone pigments.
Bilateral ptosis
MedGen UID:
356120
Concept ID:
C1865916
Disease or Syndrome
Visual impairment
MedGen UID:
777085
Concept ID:
C3665347
Finding
Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.

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