dysarthria

Ataxia with Oculomotor Apraxia 2

Clinical Characteristics
Ocular Features: 

Patients with this disorder have difficulty initiating voluntary ocular movements upon command or following targets (oculomotor apraxia).  This feature is not as prominent or frequent in AOA2 (56%) as it is in ataxia with oculomotor apraxia 1 (208920).  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.  Strabismus and nystagmus are present in a significant proportion of patients.  Optokinetic nystagmus is impaired.

Systemic Features: 

Initial development proceeds normally but cerebellar ataxia with significant gait problems appear toward the end of the first decade of life and sometimes not until the third decade (mean age of onset 15 years).   Distal muscle weakness and atrophy are often seen.  Mental decline has been observed in a few individuals but does not occur until midlife.  Sensorimotor deficits are present in many patients.  Tremors, dystonia, and choreiform movements are sometimes seen.  Many patients become wheelchair-bound by the 4th decade of life.

Cerebellar atrophy is revealed by MRI.  Serum alpha-fetoprotein concentrations are usually elevated while serum creatine kinase is increased in some patients.  Circulating cholesterol may also be above normal.  Mild serum changes in these components may be seen in heterozygotes.  Hypoalbuminemia is not present in AOA2.

Genetics

Homozygous mutations in SETX (9q34.13) are responsible for this disorder.  Ataxia with oculomotor apraxia 2 is distinguished from ataxia-telangiectasia (208900) by the lack of telangiectases and immunological deficiencies. It differs from ataxia with oculomotor apraxia 1 (208920) in having a somewhat later onset, somewhat slower course, and milder oculopraxic manifestations. Cogan-type oculomotor apraxia (257550) lacks other neurologic signs. Oculomotor apraxia may be the presenting sign in Gaucher disease (230800, 230900, 231000).

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

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no beneficial treatment for the neurological disease but physical therapy, speech therapy, and sometimes special education can be helpful.

References
Article Title: 

Epidemiological, clinical, paraclinical and molecular study of a cohort of 102 patients affected with autosomal recessive progressive cerebellar ataxia from Alsace, Eastern France: implications for clinical management

Anheim M, Fleury M, Monga B, Laugel V, Chaigne D, Rodier G, Ginglinger E, Boulay C, Courtois S, Drouot N, Fritsch M, Delaunoy JP, Stoppa-Lyonnet D, Tranchant C, Koenig M. Epidemiological, clinical, paraclinical and molecular study of a cohort of 102 patients affected with autosomal recessive progressive cerebellar ataxia from Alsace, Eastern France: implications for clinical management. Neurogenetics. 2010 Feb;11(1):1-12.

PubMed ID: 
19440741

Ataxia with oculomotor apraxia type 2: a clinical, pathologic, and genetic study

Criscuolo C, Chessa L, Di Giandomenico S, Mancini P, Sacc?+ F, Grieco GS, Piane M, Barbieri F, De Michele G, Banfi S, Pierelli F, Rizzuto N, Santorelli FM, Gallosti L, Filla A, Casali C. Ataxia with oculomotor apraxia type 2: a clinical, pathologic, and genetic study. Neurology. 2006 Apr 25;66(8):1207-10.

PubMed ID: 
16636238

Spastic Paraplegia 15

Clinical Characteristics
Ocular Features: 

Yellowish flecks resembling those seen in fundus flavimaculatus are present, primarily in the macular area.   These can be present in large numbers in homozygotes with the full neurological syndrome.  Background retinal pigmentation appears clinically normal but fluorescein angiography shows a strikingly mottled picture with areas of hyper- and hypofluorescence.  Retinal flecks have also been reported in heterozygous parents.

The central macula exhibits autofluorescence.  Standard EOG and ERG recordings are normal but multifocal electroretinography shows subnormal responses in the macular area.  Visual acuity is minimally impacted.

Systemic Features: 

This is a form of spastic paraplegia with progressive spasticity primarily affecting the lower limbs.  Mental retardation (or at least cognitive impairment), dysarthria, a thin corpus callosum, and distal amyotrophy are often present.  Hearing deficits have also been described.  Some but not all patients have tremors, cerebellar ataxia, epilepsy and behavioral disturbances. Onset is between 10 and 19 years of age.  Little is known about the rate of symptom progression.

Genetics

This is an autosomal recessive disorder resulting from mutations in the ZFYVE26 gene (14q24.1).

Spastic paraplegia 7 (607259) has similar neurological features but with ptosis, optic atrophy, and nystagmus.  Congenital cataracts occur in addition to the neurological signs in spastic paraplegia 46 (614409) .

Other disorders with retinal flecks are described in Flecked Retina Syndromes.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is known.

References
Article Title: 

Fleck retina in Kjellin's syndrome

Farmer SG, Longstreth WT Jr, Kalina RE, Todorov AB. Fleck retina in Kjellin's syndrome. Am J Ophthalmol. 1985 Jan 15;99(1):45-50.

PubMed ID: 
3966518

Friedreich Ataxia 1

Clinical Characteristics
Ocular Features: 

Nystagmus and optic atrophy are important ocular signs.  The visual pathway, both anterior and posterior, is consistently involved and field defects are common even though many patients are asymptomatic.  OCT usually shows a reduced nerve fiber layer secondary to loss of axons.  About half of patients have abnormal visual evoked potentials.  A few patients experience a sudden loss of central vision during the second decade of life.

Systemic Features: 

Friedreich ataxia is a progressive neurodegenerative disorder with onset before puberty.  The spinocerebellar tracts, dorsal columns, pyramidal tracts, cerebellum, medulla, and optic radiation, may all be involved.  The outstanding symptom is ataxia with impairment of gait and weakness in the limbs.  Muscle weakness, extensor plantar responses, and absent lower limb reflexes are usually present.  Dysarthria is usually notable.  Sensory signs include impairment of position and vibratory senses.  'Twitching' in limbs and digits is often noted and 'restless leg syndrome' is common.

Secondary changes include pes cavus, scoliosis, and hammer toe.  Cardiac disease is frequently present and heart failure is the most common cause of death.  Most patients have hypertrophic cardiomyopathy with characteristic EKG changes and some have subaortic stenosis as part of the hypertrophied myocardium.  Diabetes mellitus is present in 20-25%.  Some hearing loss occurs in more than 10% of individuals.

Most patients require a wheelchair within 15 years of disease onset and the mean age of death is about 36 years.

Rare patients with a later onset of FRDA retain lower limb deep tendon reflexes.

Genetics

Homozygous mutations in FXN (9p21.11) are responsible for Friedreich ataxia.  The most common DNA abnormality is a GAA trinucleotide repeat expansion in intron 1.  The number of repeats in patients is 70 to more than 1000 compared with 5-30 in normal individuals.  FXN encodes the mitochondrial protein frataxin.

About 2% of individuals have point mutations in FXN instead of trinucleotide repeats.

Some of the phenotypic variations may be explained by differences in the number of GAA repeats.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Treatment is largely directed at symptoms including speech and physical therapy and mobility assistive devices. Scoliosis may require surgical intervention.

References
Article Title: 

Visual system involvement in patients with Friedreich's ataxia

Fortuna F, Barboni P, Liguori R, Valentino ML, Savini G, Gellera C, Mariotti C, Rizzo G, Tonon C, Manners D, Lodi R, Sadun AA, Carelli V. Visual system involvement in patients with Friedreich's ataxia. Brain. 2009 Jan;132(Pt 1):116-23.

PubMed ID: 
18931386

Friedreich ataxia: an overview

Delatycki MB, Williamson R, Forrest SM. Friedreich ataxia: an overview. J Med Genet. 2000 Jan;37(1):1-8. Review.

PubMed ID: 
10633128

Spastic Ataxia 6, Charlevoix-Saguenay Type

Clinical Characteristics
Ocular Features: 

Patches of myelinated axons from retinal neurons in the retina are not unusual in the general population but are especially prominent among families in Canada with SPAX6.  These typically appear as striated white or yellowish-white patches with 'fuzzy' borders in the nerve fiber layer of the retina and radiate from the disc.   These findings are usually of no functional significance but if sufficiently large and dense can be demonstrated on perimetry as small scotomas.   OCT studies in two Belgian families have revealed increased thickness of the peri-papillary retinal nerve fiber layer in both patients and carriers without clinical evidence of myelination.  In addition the retinal nerve fiber layer has been described as 'hypertrophied' outside the areas of myelination.   Horizontal gaze nystagmus and deficits in conjugate pursuit movements are often present.   

Systemic Features: 

This neurodegenerative disorder begins in early childhood (12-18 months) with signs of cerebellar ataxia, pyramidal signs, and peripheral neuropathy.  Slightly older children develop a mixed-sensorimotor peripheral neuropathy. Dysarthria, limb spasticity, distal muscle wasting, and mitral valve prolapse are often present.  Knee reflexes are exaggerated while ankle reflexes are often absent.  Extensor plantar responses are usually present.  The EMG can show signs of denervation with slowed conduction while brain neuroimaging demonstrates regional atrophy in the cerebellum, especially the superior vermis.  Most patients eventually become wheelchair-bound.  However, cognitive and daily living skills are preserved into adulthood.  Most patients live into the sixth decade.

Genetics

Homozygous or compound heterozygous mutations in the SACS gene (13q12.12) are responsible for this autosomal recessive disorder.

The largest number of cases is found in the Charlevoix-Saguenay region of Quebec, Canada among the descendents of a founder but families have also been found in Asia and Europe.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment for the general disease is available but specific therapies for some functions such as urinary urgency are available.  Physical and speech therapy as well as special education assistance can be helpful for adaptation.

References
Article Title: 

Location score and haplotype analyses of the locus for autosomal recessive spastic ataxia of Charlevoix-Saguenay, in chromosome region 13q11

Richter A, Rioux JD, Bouchard JP, Mercier J, Mathieu J, Ge B, Poirier J, Julien D, Gyapay G, Weissenbach J, Hudson TJ, Melan?sson SB, Morgan K. Location score and haplotype analyses of the locus for autosomal recessive spastic ataxia of Charlevoix-Saguenay, in chromosome region 13q11. Am J Hum Genet. 1999 Mar;64(3):768-75. Erratum in: Am J Hum Genet 1999 Apr;64(4):1257.

PubMed ID: 
10053011

Spastic Ataxia 4, mtPAP Deficiency

Clinical Characteristics
Ocular Features: 

Ocular examinations in 4 adult individuals of a single family aged 18 to 27 years were reported to have optic atrophy.  One of these had a horizontal nystagmus and another was described as having a vertical nystagmus.  No ocular evaluations were available for 2 children, aged 2 and 6 years.  Visual acuity testing was not reported but all individuals participated appropriately in family and educational activities. 

Systemic Features: 

This is a congenital disorder with cerebral ataxia (limb and truncal), spastic paraparesis (increased lower limb tone with brisk knee jerks and extensor plantar responses), cerebellar and spastic dysarthria, learning difficulties and emotional lability as prominent features.  The onset of both speech and mobility are delayed.  Older individuals have slow and spastic tongue movements with brisk jaw jerks, and increased tone in the upper limbs.  Motor function progressively declines although even older individuals in the third decade of life remain mobile albeit with an increasingly spastic and ataxic gait, and require only minimal assistance with self-care.  Children in grade school require special education accommodations but there is no obvious deterioration in intellectual function as they mature.

Genetics

This is an autosomal recessive disorder resulting from homozygous mutations in the MTPAP gene (10p11.22).  The mutation leads to a defect of mitochondrial mRNA maturation in which the poly(A) tails are severely truncated.

Optic atrophy is also present in some patients who have autosomal dominant spastic ataxia with miosis (SPAX7) (108650) and in another form of autosomal recessive childhood-onset spastic ataxia and mental retardation (270500).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is known but special education and physical and speech therapy may be helpful.

References
Article Title: 

Defective mitochondrial mRNA maturation is associated with spastic ataxia

Crosby AH, Patel H, Chioza BA, Proukakis C, Gurtz K, Patton MA, Sharifi R, Harlalka G, Simpson MA, Dick K, Reed JA, Al-Memar A, Chrzanowska-Lightowlers ZM, Cross HE, Lightowlers RN. Defective mitochondrial mRNA maturation is associated with spastic ataxia. Am J Hum Genet. 2010 Nov 12;87(5):655-60.

PubMed ID: 
20970105

Cataracts, Congenital, and Hypomyelinating Leukodystrophy

Clinical Characteristics
Ocular Features: 

Bilateral cataracts may be present at birth or later in the first decade of life.  The ERG and flash VEPs are normal.

Systemic Features: 

Psychomotor development is initially normal but signs of delay are usually present during the first year of life.  Patients may be able to walk but only with support.  Pyramidal and cerebellar dysfunction, muscle weakness and wasting, dysarthria, truncal hypotonia, intention tremor, and spasticity are evident during the first decade.  Some have seizures.  Cognitive impairment ranges from mild to moderate.  Most patients become wheelchair-bound late in the first decade of life and some do not survive beyond childhood.

Hypomyelination and mild axonal loss may be seen in peripheral nerve biopsies while neuroimaging shows evidence of diffuse and progressive cerebral white matter atrophy.

Genetics

This is an autosomal recessive disorder caused by homozygous mutations in FAM126A (7p15.3) leading to a deficiency of the neuronal protein hyccin.  The result is deficient myelination in both central and peripheral nervous systems.  No symptoms are evident in heterozygotes.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

The cataracts may be surgically removed.  There is no known treatment for the progressive neurologic deterioration but physical therapy and special education may be helpful.

References
Article Title: 

Novel FAM126A mutations in Hypomyelination and Congenital Cataract disease

Traverso M, Assereto S, Gazzerro E, Savasta S, Abdalla EM, Rossi A, Baldassari S, Fruscione F, Ruffinazzi G, Fassad MR, El Beheiry A, Minetti C, Zara F, Biancheri R. Novel FAM126A mutations in Hypomyelination and Congenital Cataract disease. Biochem Biophys Res Commun. 2013 Aug 30. [Epub ahead of print] PubMed PMID: 23998934.

PubMed ID: 
23998934

Phenotypic characterization of hypomyelination and congenital cataract

Biancheri R, Zara F, Bruno C, Rossi A, Bordo L, Gazzerro E, Sotgia F, Pedemonte M, Scapolan S, Bado M, Uziel G, Bugiani M, Lamba LD, Costa V, Schenone A, Rozemuller AJ, Tortori-Donati P, Lisanti MP, van der Knaap MS, Minetti C. Phenotypic characterization of hypomyelination and congenital cataract. Ann Neurol. 2007 Aug;62(2):121-7.

PubMed ID: 
17683097

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

Spinocerebellar Ataxia 1

Clinical Characteristics
Ocular Features: 

Early manifestations include gaze-evoked nystagmus and saccadic hypermetria.  Ophthalmoplegia develops later in the disease process.  Some patients experience a decrease in acuity and dyschromatopsia.  The ERG shows evidence of generalized rod and cone photoreceptor dysfunction in some patients.  Optic atrophy, central scotomas, central RPE changes, retinal arteriolar attenuation, and blepharospasm have also been reported.

Time-domain OCT has revealed microscopic changes in the macula with thinning of the inner-outer segment junction and nuclear layer in areas with RPE hypopigmentation. 

Systemic Features: 

This is a progressive cerebellar syndrome characterized by systems of ataxia, dysarthria, and bulbar palsy.  Speech is often scanning and explosive.  DTRs can be exaggerated, and dysmetria is common.  The mean age of onset is about age 40.  Some cognitive decline may occur.  Muscle atrophy, and symptoms of peripheral neuropathy can be present.  MRI shows atrophy in the cerebellum, spinal cord, and brainstem.  There is considerable variation in clinical expression.  Individuals with adult onset of symptoms can survive for 10-30 years whereas those with a juvenile-onset often do not live beyond the age of 16 years.

Genetics

This disorder is caused by an expanded CAG repeat in the ataxin-1 gene (ATXN1) at 6p23.  It is an autosomal dominant disorder.  Alleles with 39-44 or more CAG repeats are likely to be associated with symptoms. 

A male bias and the phenomenon of anticipation have been demonstrated in this disorder as in spinocerebellar ataxia 7 (SCA7) (164500), in which affected offspring of males with SCA develop disease earlier and symptoms progress more rapidly than in offspring of females.  This is often explained by the fact that males generally transmit a larger number of CAG repeats.

SCA7 (164500), also inherited in an autosomal dominant pattern and caused by expanded CAG repeats on chromosome 3, has many similar ocular and neurologic features.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Supportive care is often required.          

References
Article Title: 

Cataracts, Ataxia, Short Stature, and Mental Retardation

Clinical Characteristics
Ocular Features: 

Cataracts are present in both sexes but the opacification is more extensive in males and only partial in females.  The cataracts are congenital in males but apparently develop later in females who complain of blurred vision from early childhood or during teenage years.  The lenses in females have punctate and pulverulent opacities as well as posterior subcapsular sclerosis.  Vision has been estimated as hand motion from early childhood in boys and about 20/40 in females in the first two decades of life.

Systemic Features: 

Males have mild to moderate mental retardation, muscle hypotonia and weakness with postural tremor.  Their standing position is broad-based and they are unable to sit or stand otherwise without some support.  They are usually unable to walk unassisted.  Speech is dysarthric and its development is delayed.  Females are neurologically normal.

Genetics

A locus containing the disease allele at Xpter-q13.1 cosegregates with the cataract phenotype in both sexes.  The gene mutation has not been identified.  This can be called an X-linked recessive disorder with partial expression in heterozygous females.

Pedigree: 
X-linked recessive, carrier mother
X-linked recessive, father affected
Treatment
Treatment Options: 

Cataract surgery may be indicated in young females and may be beneficial in infant boys.

References
Article Title: 

Neurodegeneration with Brain Iron Accumulation

Clinical Characteristics
Ocular Features: 

Optic atrophy is a major ocular feature and the primary cause of visual impairment.  A minority (25%) of patients also have a diffuse fleck retinopathy with a bull’s eye maculopathy.  Later the retinopathy may resemble retinitis pigmentosa with a bone spicule pattern. Nystagmus is often present.  These signs usually follow systemic signs such as difficulties in locomotion.  An apraxia of eyelid opening has been noted and some patients have blepharospasm. 

Systemic Features: 

This is a progressive disorder of the basal ganglia with prominent symptoms of extrapyramidal dysfunction.  Onset is in early childhood or in the neonatal period with delayed development and sometimes mental retardation.  Choreoathetoid writhing movements, stuttering, dysphagia, muscle rigidity, and intermittent dystonia are prominent features.  Seizures are uncommon.  Older individuals may exhibit dementia and ambulation is eventually impaired.  The MRI usually shows an area of hyperintensity in the medial globus pallidus that has been called the ‘eye of the tiger’ sign but this is not pathognomonic.  Axonal degeneration with accumulation of spheroidal inclusions can be seen histologically. 

Genetics

The title of this disorder ‘neurodegeneration with brain iron accumulation’ actually refers to a group of disorders with somewhat common characteristics.  Pentothenate kinase-associated neurodegeneration or NB1A1 (234200) is  the most common of these. 

Types  NBIA2A (256600) and NBIA2B (610217) are caused by mutations in the PLA2G6 gene (22q13.1).  The former can be seen neonatally but usually has its onset in the first two years of life and is sometimes called infantile neuroaxonal dystrophy or Seitelberger disease.  Death may occur before the age of 10 years.  Signs of motor neuron and cerebellar disease are more prominent than in NB1A1. 

NBIA2B has a later onset (4-5 years) and profound sensorimotor impairment but there are many overlapping features and the nosology is confusing.  Mutations in the FTL gene cause yet another form designated NBIA3 (606159) but ocular signs seem to be absent. 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is evidence that treatment with deferiprone reduces the amount of iron accumulation in the globus pallidus with motor improvement in at least some patients.  Most patients require supportive care.

References
Article Title: 

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