external ophthalmoplegia

Spinocerebellar Ataxia 3

Clinical Characteristics
Ocular Features: 

External ophthalmoplegia in some form is usually present and there may be a supranuclear component.  Smooth horizontal movements are impaired and saccades are dysmetric.  Gaze-evoked nystagmus is a common finding.  The eyes are often described as 'bulging' and this has been attributed to eyelid retraction.  With time the abnormal saccadic movements slow resulting in ophthalmoparesis with restriction of upgaze.

Systemic Features: 

This form of spinocerebellar ataxia is considered to be the most frequent.  It is a progressive disease in all aspects which accounts for some of the considerable clinical heterogeneity reported.  Onset is likewise highly variable depending upon the number of repeats but usually sometime between the second to fifth decades.  In a large cohort of Azorean individuals the mean age of onset was reported to be 37 years.

An unsteady gait, dysarthric speech, general clumsiness, and diplopia are among the early symptoms.  Nystagmus, spasticity, and various autonomic signs including reduced bladder control may also be noted.  Chronic pain, sleep disturbances, impaired mental functioning, and memory deficits are often present and some authors have labelled these as indicative of dementia.

Virtually all clinical signs progress with ambulation difficulties requiring the need for assistive devices about a decade after the onset of disease.  Eventually signs of brain stem involvement appear with facial atrophy, perioral twitching, tongue fasciculations and atrophy, and dysphagia. Some degree of peripheral polyneuropathy with muscle wasting and loss of sensation are often present.  Tremors and other signs of Parkinsonism may be present.  Dystonic movements are often seen.

Imagining of the brain has revealed pontocerebellar atrophy and enlargement of the 4th ventricle but this is variable.  Nerve conduction studies documents involvement of the sensory nerves.  Neuropathologic studies show widespread neuronal loss in the CNS and spinal cord.

Genetics

This is considered to be an autosomal dominant disorder caused by an excess of heterozygous trinucleotide repeats in the ataxin3 gene (14q32) encoding glutamine.  The number in normal individuals is up to 44 repeats whereas patients with SCA3 have 52-86 repeats.  However, clinical signs of SCA3 have been found in patients with as few as 45 glutamine repeats.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Physical and occupational therapy combined with regular exercise has been reported to slow the progression of symptoms.

References
Article Title: 

Machado-Joseph disease

Sudarsky L, Coutinho P. Machado-Joseph disease. Clin Neurosci. 1995;3(1):17-22. Review.

PubMed ID: 
7614089

Encephalopathy Due To Defective Mitochondrial And Peroxisomal Fission 2

Clinical Characteristics
Ocular Features: 

Visual impairment and optic atrophy are usually present.  Visual-evoked potentials may be negative or slowed severely.  Some degree of ophthalmoparesis is often present while frank external ophthalmoplegia can develop in the second year of life.  In one patient aged 7 years, MRI showed increased T2 signals in the optic radiation.

Systemic Features: 

Microcephaly becomes evident in the first year of life and seizures can appear in this period as well.  General developmental delays are present.  There may be evidence of Leigh-like basal ganglia disease.  Dysphagia may require the placement of a gastroscopy tube.  Truncal hypotonia can be so severe that sitting and head control are not possible.  However, there is often spasticity and hyperreflexia in the limbs.  EEG recordings show hypsarrhythmia.

Brain MRI may show increased T2 signaling in the global pallidus, thalamus, and the subthalamic nucleus.

Patients may never be able to sit or walk and usually do not develop speech.  

Genetics

Homozygous or compound heterozygous truncating mutations in the MFF gene (mitochondrial fission factor) (2q36.3) is responsible for this condition.  Patients with EMPF2 may have abnormally elongated and tubular mitochondria and peroxisomes in fibroblasts.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for the general disorder.  Gastrostomy tubes may be required to maintain adequate nutrition.  Airway hygiene is important.  Respiratory complications can be a factor in the early demise of children.

References
Article Title: 

Fibrosis of Extraocular Muscles with Synergistic Divergence

Clinical Characteristics
Ocular Features: 

This is an ocular motility disorder with restrictive ophthalmoplegia and anomalous eye movements.  Some individuals exhibit Marcus Gunn jaw winking and downgaze fixation along with ptosis.  MRI imaging may reveal hypoplasia of the oculomotor nerve and absence of the abducens nerve.  Sometimes one or more extraocular muscles are replaced with fibrous tissue.  Globe retraction may accompany the abduction movement.  Forced duction testing may reveal severe restriction and Bell's phenomenon may be absent.  Vertical nystagmus and jerky eye motions may accompany attempted fixation.  There is considerable asymmetry to the extraocular movements of the two eyes. 

Systemic Features: 

Some patients have oculocutaneous hypopigmentation.

Genetics

No specific mutation has been identified.  Several examples of parent to child transmission have been reported suggesting autosomal dominant inheritance.

Other nonsyndromal forms of congenital fibrosis of extraocular muscles include: CFEOM1 (135700), CFEOM2 (602078), CFEOM3C (609384), and CFEOM5 (616219), although the eye movement phenotype may vary.  See also Tukel CFEOM syndrome (609428).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Ptosis and strabismus surgery may be of benefit.

References
Article Title: 

Fibrosis of Extraocular Muscles, CFEOM3C

Clinical Characteristics
Ocular Features: 

Bilateral ptosis is present at birth and the superior rectus muscle movements are limited.  Two of the 4 affected members of the 3 generation family reported also had bilateral excyclotropia.  The extraocular muscle movement restrictions were not progressive.  On computed tomography the extraocular muscles appeared normal.

Systemic Features: 

One affected member of the pedigree had an unbalanced translocation with asymmetric facial dysmorphism with exophthalmia and ptosis. She also had physical and mental growth delay, kyphosis, pectus excavatum, limited speech, ophthalmoplegia, regression of motor skills and peripheral hypertonia with brisk reflexes.  Other members with ophthalmoplegia had no systemic findings. 

Genetics

In the reported family a balanced translocation, t(2;13)(q37.3;q12.11), was present in 3 affected. The 4th patient with syndromal ophthalmoplegia had an unbalanced translocation.  The transmission pattern of t(2;13) is consistent with autosomal dominant inheritance.

Other nonsyndromal forms of congenital fibrosis of extraocular muscles include: CFEOM1 (135700), CFEOM2 (602078), CFEOM5 (616219), and CFEOM with synergistic divergence (609612).  See also Tukel CFEOM syndrome (609428).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Ptosis surgery can be helpful.

References
Article Title: 

Assignment of a new congenital fibrosis of extraocular muscles type 3 (CFEOM3)locus, FEOM4, based on a balanced translocation t(2;13) (q37.3;q12.11) and identification of candidate genes

Aubourg P, Krahn M, Bernard R, Nguyen K, Forzano O, Boccaccio I, Delague V, De Sandre-Giovannoli A, Pouget J, Depetris D, Mattei MG, Philip N, Levy N. Assignment of a new congenital fibrosis of extraocular muscles type 3 (CFEOM3)locus, FEOM4, based on a balanced translocation t(2;13) (q37.3;q12.11) and identification of candidate genes. J Med Genet. 2005 Mar;42(3):253-9.

PubMed ID: 
15744040

Fibrosis of Extraocular Muscles, CFEOM5

Clinical Characteristics
Ocular Features: 

This type of congenital fibrosis of extraocular muscles is sometimes called a congenital cranial dysinnervation disorder.  Ptosis is of congenital onset while the nature of the strabismus is variable but bilateral.  One sib with this disorder had Duane retraction syndrome.

Systemic Features: 

No systemic features have been reported.

Genetics

Homozygosity or compound heterozygosity of mutations in the COL25A1 gene is responsible for this autosomal recessive condition. 

Other nonsyndromal forms of congenital fibrosis of extraocular muscles include: CFEOM1 (135700), CFEOM2 (602078), CFEOM3C (609384), and CFEOM with synergistic divergence (609612).  See also Tukel CFEOM syndrome (609428).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No specific treatment has been reported.  However, in selected patients the ocular deviation can be at least partially corrected with strabismus surgery.  Surgery for ptosis should also be considered.

References
Article Title: 

Perrault Syndrome

Clinical Characteristics
Ocular Features: 

Nystagmus and limited extraocular movements are usually present in PRLTS1.  Optic atrophy and poor visual acuity have been reported. Ptosis may be present.  The clinical manifestations are variable among and within the types.  Rod dysfunction and ‘retinal atrophy’ were reported in one patient.  The majority of patients have had only limited ocular evaluations.

Systemic Features: 

This is a sex-influenced condition in which both sexes have a sensorineural hearing deficit and neurodegenerative disease (both central and peripheral) but only the females have gonadal dysgenesis.  Motor development is often delayed and ataxia along with a peripheral sensory neuropathy and a variable degree of limb weakness can be present.  Learning difficulties, cognitive decline, and frank mental retardation are frequently described.  The cerebellum may be atrophic.

There is considerable variability in the clinical signs.

Genetics

The combination of hearing loss in males and females, ovarian dysgenesis in females, and variable neurologic signs including external ophthalmoplegia and sometimes optic atrophy is known as Perrault syndrome.  The ocular movement abnormalities are seen primarily in PRLTS1. 

At least 5 unique mutations have been found accounting for types PRLTS1-5.  PRLTS1 (233400) results from mutations in HSD17B4 (5q23.1), type PRLTS2 (614926) is caused by mutations in the HARS2 gene, PPRLTS3 (614129) by mutations in the CLPP gene, PRLTS4 (615300) by mutations in the LARS2 gene, and PRLTS5 (616138) by mutations in C10orf2 (listed in this database as External Ophthalmoplegia, C10orf2, and mtDNA mutations,.

The inheritance pattern among different types may be autosomal recessive or autosomal dominant.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment is known.

References
Article Title: 

Perrault syndrome: further evidence for genetic heterogeneity

Jenkinson EM, Clayton-Smith J, Mehta S, Bennett C, Reardon W, Green A, Pearce SH, De Michele G, Conway GS, Cilliers D, Moreton N, Davis JR, Trump D, Newman WG. Perrault syndrome: further evidence for genetic heterogeneity. J Neurol. 2012 May;259(5):974-6.

PubMed ID: 
22037954

Perrault syndrome in sisters

McCarthy DJ, Opitz JM. Perrault syndrome in sisters. Am J Med Genet. 1985 Nov;22(3):629-31.

PubMed ID: 
4061497

Ataxia with Oculomotor Apraxia 1

Clinical Characteristics
Ocular Features: 

Patients with this disorder have difficulty initiating voluntary ocular movements upon command or when following targets (oculomotor apraxia).  Gaze changes are often initiated first by head thrusting, followed by saccadic eye movements.  One may test for this by holding the head whereupon the patient is unable to move the eyes.  Ocular apraxia is often evident a few years after symptoms of ataxia are noted and may progress to external ophthalmoplegia.  Most patients have exaggerated blinking.

Systemic Features: 

The ataxia is cerebellar in origin with onset usually in the first decade of life (mean age of onset 4.3 years). It is associated with peripheral axonal neuropathy and hypoalbuminemia. Gait imbalance is usually the first symptom followed by upper limb dysmetria.  Other variable signs include dysarthria, choreiform or athetoid movements, facial grimacing, tongue and limb fasciculations, areflexia, and distal sensory deficits.   All symptoms are progressive and ambulation is lost within a decade of onset.  Cerebellar atrophy may be seen on MRI and the EMG shows evidence of axonal neuropathy.  Mental function is normal in most patients but some have cognitive impairments.

Genetics

Mutations in the APTX gene (9p21.1) encoding aprataxin are responsible for this autosomal recessive condition. 

There is evidence of clinical and genetic heterogeneity.  At least two loci are involved, with the mutation at 9p13 causing an earlier onset of disease (first decade), and hypoalbuminemia, while the second one, ataxia with oculomotor apraxia 2  [606002]) at 9q34 causes a disorder of later onset (2nd or third decade) in which oculomotor apraxia is an inconsistent finding.  Oculomotor apraxia is more consistently found in the disorder described here.  Cogan-type oculomotor apraxia (257550) lacks other neurologic signs.

See also Ataxia with Oculomotor Apraxia 3 (615217), and Ataxia with Oculomotor Apraxia 4 (616267).

Oculomotor apraxia may be the presenting sign in Gaucher disease (230800, 230900, 231000). 

The ocular phenotype is similar to that seen in ataxia-telangiectasia (208900).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No specific treatment is available although physical therapy can be helpful.

References
Article Title: 

Aprataxin gene mutations in Tunisian families

Amouri R, Moreira MC, Zouari M, El Euch G, Barhoumi C, Kefi M, Belal S, Koenig M, Hentati F. Aprataxin gene mutations in Tunisian families. Neurology. 2004 Sep 14;63(5):928-9.

PubMed ID: 
15365154

Kearns-Sayre Syndrome

Clinical Characteristics
Ocular Features: 

Ptosis and progressive ophthalmoplegia usually have their onset before the second decade of life.  Pigmentary retinopathy is common with a variable clinical pattern of simple salt-and-pepper pigmentation or pigmentary clumping resembling retinitis pigmentosa.

Systemic Features: 

Atrioventricular conduction defects including complete heart block, cardiomyopathy, short stature, elevated CSF protein, and ataxia are among the most frequent extraocular features seen.  Pharyngeal, facial, and skeletal muscle weakness seem to be common features.  Growth retardation, delayed sexual maturation, and mental deterioration occur in some patients. Older patients have a sensorineural hearing deficit as well.

EEG abnormalities are often present.  CT scans reveals a diffuse leukoencephalopathy as well as a variety of CNS abnormalities in the cerebellum and brain stem.  Muscle biopsies reveal 'ragged red' fibers.

This is a progressive disorder and many patients die in the third or fourth decades of life.

Genetics

Unlike many syndromes of external ophthalmoplegia with deletions in mitochondria, no nuclear DNA mutations have been associated with this disorder.  However, it is a clinically and genetically heterogeneous condition.  Exclusively maternal transmission consistent with mitochondrial disease has been observed in some familial cases.  Other familial cases suggest autosomal inheritance and in some the transmission pattern is consistent with autosomal recessive inheritance.  Many if not most cases occur sporadically.

Mitochondrial DNA defects in muscle and brain vary in size and location and even the proportion of normal to abnormal mitochondria among cells varies. This may account for some of the clinical heterogeneity.

Treatment
Treatment Options: 

Coenzyme Q(10) may decrease fatigue with improvement in eye muscle movement and a lessening in the degree of heart block.  Pacemakers may be necessary in some patients.  Exercise is recommended for patients with significant skeletal myopathy.

References
Article Title: 

External Ophthalmoplegia, C10ORF2 and mtDNA Mutations

Clinical Characteristics
Ocular Features: 

Ptosis and external ophthalmoplegia are found in almost all patients.  These have a variable onset with some patients not symptomatic until midlife or later.  External ophthalmoplegia may be the only symptom.  Onset in late adolescence has also been reported.  Cataracts often occur.

Systemic Features: 

About half (52%) of patients have fatigue and weakness.  Ataxia and peripheral neuropathy with paresthesias are sometimes present. Some patients report bulbar symptoms of dysphagia, dysarthria and dysphonia.  Skeletal muscle biopsies show typical ragged red fibers and evidence of mitochondrial dysfunction with cytochrome c oxidase (COX) deficiency.  Late onset of typical features of parkinsonism including a resting tremor, rigidity, and bradykinesia is seen in some patients.  Several individuals have reported major depression and/or bipolar disorder. Myopathy (33%) with muscle wasting and respiratory difficulties can occur.   As many as 24% of patients have cardiac abnormalities consisting primarily of conduction defects.

Genetics

This an autosomal dominant disorder secondary to mutations in the C10ORF2 (Twinkle) gene (10q24) in association with mitochondrial DNA depletion.  It accounts for approximately 35% of autosomal dominant cases of external ophthalmoplegia.

At least two additional mutations cause similar external ophthalmoplegia syndromes: PEOA1 (157640, 258450), and PEOA2 (609283).

The same gene may have mutations that are responsible for spinocerebellar ataxia, infantile-onset (271245), a more generalized and progressive neurodegenerative disease transmitted in an autosomal recessive pattern.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No effective treatment is known.

References
Article Title: 

The clinical, histochemical, and molecular spectrum of PEO1(Twinkle)-linked adPEO

Fratter C, Gorman GS, Stewart JD, Buddles M, Smith C, Evans J, Seller A, Poulton J, Roberts M, Hanna MG, Rahman S, Omer SE, Klopstock T, Schoser B, Kornblum C, Czermin B, Lecky B, Blakely EL, Craig K, Chinnery PF, Turnbull DM, Horvath R, Taylor RW. The clinical, histochemical, and molecular spectrum of PEO1(Twinkle)-linked adPEO. Neurology. 2010 May 18;74(20):1619-26.

PubMed ID: 
20479361

External Ophthalmoplegia, ANT1 and mtDNA Mutations

Clinical Characteristics
Ocular Features: 

Ptosis and progressive external ophthalmoplegia are the outstanding features of this form of external ophthalmoplegia.  These symptoms may appear in early adulthood.  A few patients have had thyroid disease as well.  Muscle biopsies from limb muscles show the characteristic ragged red appearance of myopathy in a minority of fibers.  Multiple deletions occur in the mitochondria of skeletal muscles.  EMG studies show myopathy while nerve conduction studies are normal.  Respiratory chain analysis often shows evidence of mitochondrial dysfunction.

Systemic Features: 

Adult patients with SLC25A4 (4q35.1) and mtDNA (ANT1) mutations have exercise intolerance and sometimes skeletal muscle weakness.  They are less likely to have symptoms of parkinsonism or peripheral neuropathy than those with mutations in POLG.  Hearing loss is minimal.

Genetics

This autosomal dominant disorder results from the combination of a mutation in the ANT1 (SLC25A4) gene (4q35) (encoding the adenine nucleotide translocator-1) and mitochondrial DNA deletions.  About 11% of autosomal dominant cases with progressive external ophthalmoplegia have mutations in this gene.  Most reported families have been from Italy.

External ophthalmoplegia may also result from mutations in POLG (most common), and in C10ORF2.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No effective treatment is available.

References
Article Title: 

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