cerebellar atrophy

PEHO Syndrome

Clinical Characteristics
Ocular Features: 

Optic atrophy is a common feature.  There may be lack of visual fixation from birth or sometimes several months later, attributed to cortical inattention.  Flash visual evoked potentials may be unrecordable. Pupillary responses to light are 'weak' and sluggish. Epicanthal folds may be seen.

Systemic Features: 

Infants are usually born with a normal head circumference but fall behind (2 SD or more) in the first year.  They have neonatal and infantile central hypotonia with brisk peripheral tendon reflexes during early childhood.  They are sometimes described as drowsy or lethargic.  Facial and limb edema can be extensive but transient sometimes and can disappear later in childhood.  The fingers are tapered.  The cheeks are full, the mouth is usually open and the upper lip appears 'tented'.  Global developmental delay is common and normal milestones are seldom attained.  Some patients have been described as severely retarded mentally.  Infantile spasms and myoclonic jerkingcan be seen within the first months of life while frank seizures with hypsarrhythmia are common in the first year of life.  Status epilepticus is a common occurrence.  General drowsiness and poor feeding are often features.  Death usually occurs in infancy or early childhood.  Midface hypoplasia and micrognathia are often present.

Brain imaging (MRI) and histology show severe alterations in myelination and cellular organization.  Neuronal loss is seen in the inner granular layer of the cerebellum but there is relative preservation of Purkinje cells.  General and progressive atrophy of the cerebellum and brain stem have been described.

Genetics

Homozygous frameshift mutations in ZNHIT3 (17q12) have been identified in affected members of several consanguineous families.  The presumed mutation seems to be most prevalent in Finland.

A somewhat similar disorder known as PEHO-like syndrome (617507) is the result of homozygous mutations in the CCDC88A gene.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Physical therapy to prevent contractures and general supportive care can be helpful.  Supplemental feeding may be required. 

References
Article Title: 

The PEHO syndrome

Riikonen R. The PEHO syndrome. Brain Dev. 2001 Nov;23(7):765-9. Review.

PubMed ID: 
11701291

Pontocerebellar Hypoplasia 3

Clinical Characteristics
Ocular Features: 

Optic atrophy is an inconsistent feature (sometimes even unilateral) of patients with PCH.  Cortical blindness has also been described.  There may be dysmorphic facial features such as wide palpebral fissures, epicanthal folds, and prominent eyes. 

Systemic Features: 

Infants are generally small and hypotonic at birth.  The skull is small and often brachycephalic.  The ears are large and low-set and  facial dysmorphism (full cheeks, long philtrum) is present.  Infants have poor head control and truncal ataxia.  Later, hyperreflexia and spasticity become evident.  Seizures are common.  Developmental delays, both somatic and mental, are nearly universal and large joint contractures are often seen. Many of these signs are progressive.  

Brain imaging generally reveals cerebral and cerebellar atrophy, a hypoplastic corpus callosum, a small cerebellar vermis, and a hypoplastic brainstem.  Short stature is a feature and early death often occurs.

Genetics

PCH3 is one of at least 10 syndromes belonging to a clinically and genetically heterogeneous group of conditions known as pontocerebellar hypoplasias.  Members of this group, while individually rare, nevertheless collectively account for a significant proportion of what was once labeled cerebral palsy.

PCH3 results from homozygous mutations in the PCLO gene (7q21). 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for the general disorder.

References
Article Title: 

Loss of PCLO function underlies pontocerebellar hypoplasia type III.

Ahmed MY, Chioza BA, Rajab A, Schmitz-Abe K, Al-Khayat A, Al-Turki S, Baple EL, Patton MA, Al-Memar AY, Hurles ME, Partlow JN, Hill RS, Evrony GD, Servattalab S, Markianos K, Walsh CA, Crosby AH, Mochida GH. Loss of PCLO function underlies pontocerebellar hypoplasia type III. Neurology. 2015 Apr 28;84(17):1745-50.

PubMed ID: 
25832664

Ataxia with Oculomotor Apraxia 4

Clinical Characteristics
Ocular Features: 

Oculomotor apraxia is usually noted after the ataxia and dystonia are apparent.

Systemic Features: 

The mean age of first symptoms is 4.3 years with dystonia being the first symptom.  Cerebellar ataxia is usually the second symptom to appear.  Cognitive impairment is present in most but not all patients with this condition.  This can progress to severe dementia in some individuals.  Dystonia may become attenuated with time.  Peripheral neuropathy with decreased vibration sense and areflexia is often present.  Cerebellar atrophy is present in all patients.

Motor difficulties such as weakness and muscle atrophy may lead to loss of independent mobility by the second to third decades.

Genetics

Homozygous or compound heterozygous mutations in the PNKP gene (19q13.33) are responsible for this disorder.

Mutations in this gene have also been associated with an infantile form of epileptic encephalopathy, microcephaly, and developmental delay (613402).

See also Ataxia with Oculomotor Apraxia 1 (208920) with hypoalbuminemia, Ataxia with Oculomotor Apraxia 2 (606002), and Ataxia with Oculomotor Apraxia 3 (615217).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no general treatment for this condition but physical therapy may be helpful in the early stages.

References
Article Title: 

Spinocerebellar Ataxia 18

Clinical Characteristics
Ocular Features: 

Ocular signs in SCAR18 include nystagmus, oculomotor apraxia, and optic atrophy.  The nystagmus may be rotatory or horizontal and can be gaze-evoked.  Some patients have intermittent and tonic upgaze.  Visual acuity has not been reported.

Systemic Features: 

Patients are developmentally delayed and have intellectual disability.  These features do not seem to be progressive.  Ataxia, both truncal and cerebellar, is present.  Mobility is impaired from early childhood and eventually requires assistance.   Joint contractures sometimes develop and patients can be wheelchair-bound by the second decade.  Dysarthric speech is common.  No dysmorphic facial features are present.

Brain imaging shows progressive cerebellar and sometimes cerebral atrophy.

Genetics

This autosomal recessive disorder results from homozygous deletions in the GRID2 gene (4q22).  This gene codes for a subunit of the glutamate receptor channel and is thought to be selectively expressed in the Purkinje cells of the cerebellum.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.  However, physical therapy, assistive devices for mobility, and low vision aids may be helpful.

References
Article Title: 

Microphthalmia, Syndromic 10

Clinical Characteristics
Ocular Features: 

Microphthalmia seems to be a common feature.  The globes have anterior-posterior dimensions of 5-8 mm.  No internal ocular structures can be visualized and individuals are likely blind.  The corneal diameters in two patients were measured at 3-4 mm.  The optic nerves have been described as ‘slender’ on brain imaging.

Systemic Features: 

Head circumference ranges from the 10th to the 25th percentile at birth  Psychomotor development has been described as normal during the first 6 to 8 months but is followed by rapid deterioration in performance with spasticity, vomiting and continuous crying.  An MRI on one 3 day old patient was reported as normal while at 15 months of age there was atrophy of the vermis and corpus callosum and at 8 years of age the atrophy of these structures was even more extensive.  Similar atrophy patterns were seen in the two other patients and eventually all cerebral while matter is lost and there is atrophy of the brainstem as well. 

Genetics

Three children from 3 consanguineous Pakistani families have been reported but no locus or mutation has been identified.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is known.

References
Article Title: 

Spinocerebellar Ataxia 38

Clinical Characteristics
Ocular Features: 

Gaze-evoked nystagmus is present with the onset of ataxia.  Some patients report diplopia.  Saccadic movements are described as slow.  Visual acuities and the appearance of the retina and optic nerve have not been reported.

Systemic Features: 

Truncal and gait ataxia are generally evident by age 40 years and progressively worsen.  Mobility requires assistance usually by age 50.  Mild sensory complaints are present in the majority of individuals.  Dysarthria is often a feature.

MRI reveals cerebellar atrophy with no evidence of brainstem involvement.

Genetics

Heterozygous mutations in the ELOVL5 gene (6p12.1) are responsible for this autosomal dominant disorder.  The gene is a member of family that encodes elongases that synthesize long chain fatty acids in the endoplasmic reticulum.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

None known.

References
Article Title: 

ELOVL5 mutations cause spinocerebellar ataxia 38

Di Gregorio E, Borroni B, Giorgio E, Lacerenza D, Ferrero M, Lo Buono N, Ragusa N, Mancini C, Gaussen M, Calcia A, Mitro N, Hoxha E, Mura I, Coviello DA, Moon YA, Tesson C, Vaula G, Couarch P, Orsi L, Duregon E, Papotti MG, Deleuze JF, Imbert J, Costanzi C, Padovani A, Giunti P, Maillet-Vioud M, Durr A, Brice A, Tempia F, Funaro A, Boccone L, Caruso D, Stevanin G, Brusco A. ELOVL5 mutations cause spinocerebellar ataxia 38. Am J Hum Genet. 2014 Aug 7;95(2):209-17.

PubMed ID: 
25065913

Spinocerebellar Ataxia, Infantile-Onset

Clinical Characteristics
Ocular Features: 

Ocular problems begin by about age 7 years when various degrees of ophthalmoplegia appear.  By the second decade damage to the optic nerves is evident (optic atrophy) leading to severe vision loss.

Systemic Features: 

This mitochondrial DNA depletion syndrome allows normal development in the first year of life.  By 10-18 months of age, muscle weakness and coordination become evident.  Deep tendon reflexes are diminished or absent.  The muscle deficits are relentlessly progressive and by teenage years most individuals are wheelchair-bound.  Generalized seizures are common.  Facial and limb dyskinesia of an athetoid nature is evident to a variable degree.  A sensory polyneuropathy develops in many patients.  Cerebellar atrophy is evident on neuroimaging.

Neurosensory hearing loss may become evident late in the first decade of life.  The amount of hearing loss is progressive, leading eventually to profound deafness.  Some patients experience a complete loss of vestibular caloric responses. 

Most individuals live to adulthood but a severe form of this disease in which liver damage and encephalopathy occur limits the lifespan to about 5 years.

Genetics

This infantile-onset form of spinocerebellar atrophy results from homozygous or compound heterozygous mutations in the C10ORF2 gene (10q24) which encodes the so-called Twinkle and Twinky mitochondrial proteins. Since the Twinkle protein is involved in the production and maintenance of mitochondrial DNA, its malfunction leads to reduced quantities of mtDNA in the liver and CNS but not in skeletal muscle.

Mutations in the C10ORF2 gene affecting the Twinkle protein may be responsible for an autosomal dominant progressive ophthalmoplegia (609286) in which ptosis and cataracts are often found but the more extensive muscle and sensory deficits are often missing.  This is one of the better examples of seemingly unique, allelic phenotypes resulting from different mutations in the same gene.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment has been reported but physical therapy, assistive hearing devices, and low vision aids might be helpful in selected patients.

References
Article Title: 

Infantile onset spinocerebellar ataxia caused by compound heterozygosity for Twinkle mutations and modeling of Twinkle mutations causing recessive disease

Pierce SB, Gulsuner S, Stapleton GA, Walsh T, Lee MK, Mandell JB, Morales A, Klevit RE, King MC, Rogers RC. Infantile onset spinocerebellar ataxia caused by compound heterozygosity for Twinkle mutations and modeling of Twinkle mutations causing recessive disease. Cold Spring Harb Mol Case Stud. 2016 Jul;2(4):a001107. doi: 10.1101/mcs.a001107.

PubMed ID: 
27551684

Spinocerebellar Ataxia, Autosomal Recessive 7

Clinical Characteristics
Ocular Features: 

Nystagmus and saccadic pursuit eye movements are common signs.  Some patients complain of diplopia.  No other ocular abnormalities are present.

Systemic Features: 

Symptoms have their onset in late childhood and are slowly progressive.  Walking and balancing are difficult.  Dysarthria, postural tremor, and limb ataxia are evident in adults.  Fine motor movements are difficult and there is often a tremor in the hands.  Deep tendon reflexes are abnormally brisk and extensor plantar responses are seen in some individuals.  Vibration sense may be diminished.  These signs are variable as is the rate of progression.  Usually patients remain mobile and productive through the fourth decade of life.  They may become wheelchair-bound by the fifth or sixth decade.  There is no cognitive impairment.

Genetics

This is an autosomal recessive condition secondary to homozygous mutations in TPP1(11p15).

The same gene is mutated in neuronal ceroid lipofuscinosis 2 (CLN2, 204500), a far more serious condition with epilepsy, optic atrophy, retinal degeneration, and a rapidly progressive course leading to early death in many individuals. It has been suggested that mutations resulting in the more severe CLN2 phenotype completely or nearly completely abolish TPP1 enzyme activity whereas those that cause SCAR7 simply result in diminished activity.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment is known for the neurological symptoms but physical therapy and mobility devices could be helpful in maintaining ambulation.  Speech therapy could be useful for dysarthria.

References
Article Title: 

Autosomal Recessive Spinocerebellar Ataxia 7 (SCAR7) is Caused by Variants in TPP1, the Gene Involved in Classic Late-Infantile Neuronal Ceroid Lipofuscinosis 2 Disease (CLN2 Disease)

Sun Y, Almomani R, Breedveld GJ, Santen GW, Aten E, Lefeber DJ, Hoff JI, Brusse E, Verheijen FW, Verdijk RM, Kriek M, Oostra B, Breuning MH, Losekoot M, den Dunnen JT, van de Warrenburg BP, Maat-Kievit AJ. Autosomal Recessive Spinocerebellar Ataxia 7 (SCAR7) is Caused by Variants in TPP1, the Gene Involved in Classic Late-Infantile Neuronal Ceroid Lipofuscinosis 2 Disease (CLN2 Disease). Hum Mutat. 2013 Feb 15. [Epub ahead of print].

PubMed ID: 
23418007

Spastic Paraplegia 46

Clinical Characteristics
Ocular Features: 

Congenital cataracts (not further described) have been reported in several individuals with this type of complicated spastic paraplegia.  Optic atrophy and nystagmus have not been reported.

Systemic Features: 

Stiffness and weakness of the lower limbs begins between 2 and 20 years of age.  This is slowly progressive although most individuals are still mobile with mild to moderate handicaps into the 4th decade.  The gait is spastic with weakness, hyperreflexia, and extensor plantar responses in the lower limbs.  The upper limbs are variably involved and movements are dysmetric.  Dysarthria and bladder dysfunction are often present.  Cerebellar ataxia is common and some patients first present with this as a prominent sign in the first and second decades.  Early cognitive development is normal but mild cognitive decline appears eventually.  Pes cavus and scoliosis may occur.

Brain imaging can show thinning of the corpus callosum, with mild cerebellar and cerebral atrophy.

Genetics

Linkage analysis identified a locus at 9p13.3 and sequencing confirmed homozygous or compound heterozygous mutations in GBA2.  The presence of parental consanguinity in some families supports autosomal recessive inheritance.

This database contains two other types of autosomal spastic paraplegia with ocular signs: spastic paraplegia 15 (270700) with a "flecked retina", and spastic paraplegia 7 (607259) with optic atrophy and nystagmus.  Cataracts have not been reported in these two conditions.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment is known for the neurological deficits but cataract surgery may be beneficial for visually significant cataracts.

References
Article Title: 

Mutations in GBA2 cause autosomal-recessive cerebellar ataxia with spasticity

Hammer MB, Eleuch-Fayache G, Schottlaender LV, Nehdi H, Gibbs JR, Arepalli SK, Chong SB, Hernandez DG, Sailer A, Liu G, Mistry PK, Cai H, Shrader G, Sassi C, Bouhlal Y, Houlden H, Hentati F, Amouri R, Singleton AB. Mutations in GBA2 cause autosomal-recessive cerebellar ataxia with spasticity. Am J Hum Genet. 2013 Feb 7;92(2):245-51. PubMed PMID: 23332917.

PubMed ID: 
23332917

Loss of function of glucocerebrosidase GBA2 is responsible for motor neuron defects in hereditary spastic paraplegia

Martin E, Sch?ole R, Smets K, Rastetter A, Boukhris A, Loureiro JL, Gonzalez MA, Mundwiller E, Deconinck T, Wessner M, Jornea L, Oteyza AC, Durr A, Martin JJ, Schols L, Mhiri C, Lamari F, Z?ochner S, De Jonghe P, Kabashi E, Brice A, Stevanin G. Loss of function of glucocerebrosidase GBA2 is responsible for motor neuron defects in hereditary spastic paraplegia. Am J Hum Genet. 2013 Feb 7;92(2):238-44. PubMed PMID: 23332916.

PubMed ID: 
23332916

A new locus (SPG46) maps to 9p21.2-q21.12 in a Tunisian family with a complicated autosomal recessive hereditary spastic paraplegia with mental impairment and thin corpus callosum

Boukhris A, Feki I, Elleuch N, Miladi MI, Boland-Aug?(c) A, Truchetto J, Mundwiller E, Jezequel N, Zelenika D, Mhiri C, Brice A, Stevanin G. A new locus (SPG46) maps to 9p21.2-q21.12 in a Tunisian family with a complicated autosomal recessive hereditary spastic paraplegia with mental impairment and thin corpus callosum. Neurogenetics. 2010 Oct;11(4):441-8.

PubMed ID: 
20593214

Congenital Disorder of Glycosylation, Type Ia

Clinical Characteristics
Ocular Features: 

Strabismus, roving eye movements (and nystagmus), and visual inattention are found in nearly all patients. Esotropia with defective abduction seems to be the most common oculomotor finding and may be present at birth.  Cataracts, ocular colobomas, oculomotor apraxia, disc pallor, and glaucoma have also been reported.  Vision is always subnormal. Reports of ocular disease before modern genotyping are not specific to the subtypes of CDG I now recognized.

This is a congenital, progressive disorder of photoreceptor degeneration with a later onset of progressive pigmentary retinopathy.  It is described in some cases as a typical retinitis pigmentosa.  The ERG is abnormal in all patients even if the pigmentary pattern is atypical for RP.  Rod responses are usually absent while the cone b-wave implicit time is delayed.  The degree of photoreceptor damage is variable, however.  Extended retinal function among younger patients suggest that the ‘on-pathway’ evolving synapses in the outer plexiform layer among photoreceptors, bipolar cells, and horizontal cells is severely dysfunctional.

Systemic Features: 

This is a multisystem disorder, often diagnosed in the neonatal period by the presence of severe encephalopathy with hypotonia, hyporeflexia, and poor feeding.  Failure to thrive, marked psychomotor retardation, delayed development, growth retardation, and ataxia become evident later in those who survive.  Cerebellar and brainstem atrophy with a peripheral neuropathy can be demonstrated during late childhood.  Some older patients have a milder disease, often with muscle atrophy and skeletal deformities such as kyphoscoliosis and a fusiform appearance of the digits.  Maldistribution of subcutaneous tissue is often seen resulting in some dysmorphism, especially of the face.  Hypogonadism and enlargement of the labia majora are commonly present.  Some patients have evidence of hepatic and cardiac dysfunction which together with severe infections are responsible for a 20% mortality rate in the first year of life.

Genetics

This is one of a group of genetically (and clinically) heterogeneous autosomal recessive conditions caused by gene mutations that result in enzymatic defects in the synthesis and processing of oligosaccharides onto glycoproteins. This type (Ia) is the most common.   The mutation lies in the PMM2 gene (16p13.2).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Most children require tube feeding with nutritional supplements.  The risk of systemic infections is high.  Those patients who survive into the second decade and beyond may require orthopedic procedures and are confined to wheelchairs.  Physical, occupational, and speech therapy along with parental support are important.

References
Article Title: 

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