nystagmus

Spastic Ataxia 8, Autosomal Recessive, with Hypomyelinating Leukodystrophy

Clinical Characteristics
Ocular Features: 

Reported ocular signs are limited to abnormal eye movements.  In other forms of spastic ataxia, nystagmus is evident in association with optic atrophy but no fundus examinations are reported in the 3 families with SPAX8.  Hypometric saccades and limited upgaze have also been found in these families.

Systemic Features: 

First signs and symptoms occur sometime in the first 5 years of life and often in the first year.   In 6 of 7 reported patients the presenting sign was nystagmus but one individual with reported onset of disease at age 5 years presented with ataxia.  Cerebellar signs, both truncal and limb, are usually present and the majority of individuals have evidence of dystonia.  Likewise, pyramidal signs are nearly always present.  Cerebellar dysarthria and titubation are often present with dystonic posturing and torticollis. 

Brain MRIs usually reveal cerebellar atrophy and widespread hypomyelination.  Two individuals in a single family had severe global psychomotor delays as well.  No sensory deficits were reported.  This disorder is progressive and patients in adulthood may require the use of a wheelchair.

Genetics

Homozygous mutations in the NKX6-2 (NKX6-2) gene (10q26.3) are responsible for this disorder.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported for the general condition.

References
Article Title: 

Mutations in NKX6-2 Cause Progressive Spastic Ataxia and Hypomyelination

Chelban V, Patel N, Vandrovcova J, Zanetti MN, Lynch DS, Ryten M, Botia JA, Bello O, Tribollet E, Efthymiou S, Davagnanam I; SYNAPSE Study Group, Bashiri FA, Wood NW, Rothman JE, Alkuraya FS, Houlden H. Mutations in NKX6-2 Cause Progressive Spastic Ataxia and Hypomyelination. Am J Hum Genet. 2017 Jun 1;100(6):969-977.

PubMed ID: 
28575651

Neurodevelopmental Disorder with Progressive Microcephaly, Spasticity, and Brain Anomalies

Clinical Characteristics
Ocular Features: 

 Examined patients have optic atrophy with nystagmus and roving eye movements.

Systemic Features: 

There are extensive and, in most cases, progressive CNS abnormalities resulting in severe neurodevelopmental deficits.  Infants at birth have progressive truncal hypotonia and limb spasticity.  Motor deficits result in little spontaneous movement, resulting in poor sucking, and respiratory difficulties.  Language does not develop and there is profound mental retardation. Progressive microcephaly is a characteristic finding.  There are often extrapyramidal signs such as rigidity and dystonic posturing.

Dysmorphic features include a short nose, high-arched palate, low-set and posteriorly rotated ears, micrognathia, postaxial polydactyly, hirsutism, pectus carinatum, contractures of large joints, and hyperextensibility of small joints.

Brain imaging shows a progressive leukoencephalopathy, cerebral and cerebellar atrophy, and delayed myelination.  The corpus callosum is often thin and the ventricles appear enlarged.  The lifespan is generally short with death occurring in infancy or early childhood.

Genetics

This autosomal recessive disorder results from homozygous mutations in the PLAA gene (9p21). 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

PLAA Mutations Cause a Lethal Infantile Epileptic Encephalopathy by Disrupting Ubiquitin-Mediated Endolysosomal Degradation of Synaptic Proteins

Hall EA, Nahorski MS, Murray LM, Shaheen R, Perkins E, Dissanayake KN, Kristaryanto Y, Jones RA, Vogt J, Rivagorda M, Handley MT, Mali GR, Quidwai T, Soares DC, Keighren MA, McKie L, Mort RL, Gammoh N, Garcia-Munoz A, Davey T, Vermeren M, Walsh D, Budd P, Aligianis IA, Faqeih E, Quigley AJ, Jackson IJ, Kulathu Y, Jackson M, Ribchester RR, von Kriegsheim A, Alkuraya FS, Woods CG, Maher ER, Mill P. PLAA Mutations Cause a Lethal Infantile Epileptic Encephalopathy by Disrupting Ubiquitin-Mediated Endolysosomal Degradation of Synaptic Proteins. Am J Hum Genet. 2017 May 4;100(5):706-724.

PubMed ID: 
28413018

Phospholipase A2-activating protein is associated with a novel form of leukoencephalopathy

Falik Zaccai TC, Savitzki D, Zivony-Elboum Y, Vilboux T, Fitts EC, Shoval Y, Kalfon L, Samra N, Keren Z, Gross B, Chasnyk N, Straussberg R, Mullikin JC, Teer JK, Geiger D, Kornitzer D, Bitterman-Deutsch O, Samson AO, Wakamiya M, Peterson JW, Kirtley ML, Pinchuk IV, Baze WB, Gahl WA, Kleta R, Anikster Y, Chopra AK. Phospholipase A2-activating protein is associated with a novel form of leukoencephalopathy. Brain. 2017 Feb;140(Pt 2):370-386.

PubMed ID: 
28007986

Pontocerebellar Hypoplasia 7

Clinical Characteristics
Ocular Features: 

The ocular phenotype has not been fully evaluated.  Optic atrophy, nystagmus, and strabismus have been reported in addition to dysmorphic periocular features such as epicanthal folds, upslanting lid fissures, and a flattened nasal bridge.  Infants frequently do not fix and follow.

Systemic Features: 

Infants may be small at birth and subsequent psychomotor development is delayed.  The ears are large and the palate is highly arched.  Hypotonia is present from birth but spasticity with hyperreflexia may also be seen.  Brain imaging may show a thin corpus callosum as well as olivopontocerebellar hypoplasia.  The ventricles are frequently enlarged.  Patients are frequently irritable with few spontaneous movements.

Genitalia can be ambiguous and are frequently assigned to the female gender because of microphallus, fused scrotum, absent testes, and absence of the uterus.  Many such infants are found to have XY karyotypes.  Infants considered male at birth may subsequently show regression of penile corporeal tissue and may have genitalia that more closely resemble the female gender.  Pelvic imaging and laparoscopy, however, may reveal a uterus, Fallopian tubes and a blind-ending vagina with no gonadal tissue even in individuals with XY karyotypes. 

Genetics

Homozygous or compound heterozygous mutations in the TOE1 gene (1p34.1) are responsible for this condition.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Biallelic mutations in the 3' exonuclease TOE1 cause pontocerebellar hypoplasia and uncover a role in snRNA processing

Lardelli RM, Schaffer AE, Eggens VR, Zaki MS, Grainger S, Sathe S, Van Nostrand EL, Schlachetzki Z, Rosti B, Akizu N, Scott E, Silhavy JL, Heckman LD, Rosti RO, Dikoglu E, Gregor A, Guemez-Gamboa A, Musaev D, Mande R, Widjaja A, Shaw TL, Markmiller S, Marin-Valencia I, Davies JH, de Meirleir L, Kayserili H, Altunoglu U, Freckmann ML, Warwick L, Chitayat D, Blaser S, Caglayan AO, Bilguvar K, Per H, Fagerberg C, Christesen HT, Kibaek M, Aldinger KA, Manchester D, Matsumoto N, Muramatsu K, Saitsu H, Shiina M, Ogata K, Foulds N, Dobyns WB, Chi NC, Traver D, Spaccini L, Bova SM, Gabriel SB, Gunel M, Valente EM, Nassogne MC, Bennett EJ, Yeo GW, Baas F, Lykke-Andersen J, Gleeson JG. Biallelic mutations in the 3' exonuclease TOE1 cause pontocerebellar hypoplasia and uncover a role in snRNA processing. Nat Genet. 2017 Mar;49(3):457-464.

PubMed ID: 
28092684

Cataracts, Congenital, With Short Stature and Minor Skeletal Anomalies

Clinical Characteristics
Ocular Features: 

Early-onset cataracts are the main ocular feature of this syndrome.  A nonconsanguineous Korean family with 4 affected individuals has been reported.  Cataracts were diagnosed at various ages, including one adult, one juvenile, and one infant.  All had horizontal nystagmus and reduced vision even after surgical removal of the lenses.  

Systemic Features: 

Macrocephaly and short stature are consistent features.  Brachydactyly of the fingers is usually present.  The feet are described as "flat" and contain accessory navicular bones.

Genetics

A 3 generation Korean family with 4 affected members has been reported.  Three living members and a deceased grandfather had cataracts in an autosomal dominant pattern.  A mutation in the BRD4 gene (19p12.12) mutation segregated with the cataract phenotype.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Surgical removal of the cataractous lenses may be helpful in selected individuals but amblyopia is likely present as postoperative vision may remain below normal.

References
Article Title: 

Spastic Paraplegia, Intellectual Disability, Nystagmus, and Obesity

Clinical Characteristics
Ocular Features: 

Patients have deep-set eyes with nystagmus, reduced vision, and often an esotropia perhaps secondary to hypermetropia.  In one of 3 reported patients the optic discs were described pale.

Systemic Features: 

Prominent foreheads are present at birth along with full cheeks and a prominent forehead.  Children grow rapidly in the first year eventually reaching the 90th percentiles in weight, height, and head circumference although neurologically they are developmentally delayed.  Speech and walking may be delayed as well.  While limbs have increased tone together with hyperreflexia, the trunk exhibits hypotonia.

Brain imaging reveals delayed myelination, dilated lateral ventricles, reduced while matter, and cerebral atrophy.

Genetics

Heterozygous mutations in the KIDINS220 gene (2p25.1) have been identified in 3 unrelated patients.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Heterozygous KIDINS220/ARMS nonsense variants cause spastic paraplegia, intellectual disability, nystagmus, and obesity

Josifova DJ, Monroe GR, Tessadori F, de Graaff E, van der Zwaag B, Mehta SG; DDD Study., Harakalova M, Duran KJ, Savelberg SM, Nijman IJ, Jungbluth H, Hoogenraad CC, Bakkers J, Knoers NV, Firth HV, Beales PL, van Haaften G, van Haelst MM. Heterozygous KIDINS220/ARMS nonsense variants cause spastic paraplegia, intellectual disability, nystagmus, and obesity. Hum Mol Genet. 2016 Jun 1;25(11):2158-2167.

PubMed ID: 
27005418

Spastic Paraplegia 78

Clinical Characteristics
Ocular Features: 

Reduced upgaze with nystagmus and strabismus have been reported.  

Systemic Features: 

This progressive neurodegenerative disorder usually has its onset in young adults but the signs and symptoms are highly variable.  Ambulation and gait difficulties combined with spasticity and lower limb weakness are common signs.  Ataxia and dysarthria are also important signs.  Some individuals have dementia while others have only mild cognitive impairment.  Some individuals have mild signs of Parkinsonism.

Brain imaging may show cerebellar and cortical atrophy with a thin corpus callosum. 

Genetics

This condition results from homozygous or compound heterozygous mutations in the ATP13A2 gene (1p36.13).

The same gene is also mutated in the Kufor-Rakeb syndrome (606693), an early-onset form of Parkinsonism.  

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Loss-of-function mutations in the ATP13A2/PARK9 gene cause complicated hereditary spastic paraplegia (SPG78)

Estrada-Cuzcano A, Martin S, Chamova T, Synofzik M, Timmann D, Holemans T, Andreeva A, Reichbauer J, De Rycke R, Chang DI, van Veen S, Samuel J, Schols L, Poppel T, Mollerup Sorensen D, Asselbergh B, Klein C, Zuchner S, Jordanova A, Vangheluwe P, Tournev I, Schule R. Loss-of-function mutations in the ATP13A2/PARK9 gene cause complicated hereditary spastic paraplegia (SPG78). Brain. 2017 Feb;140(Pt 2):287-305.

PubMed ID: 
28137957

Genetic and phenotypic characterization of complex hereditary spastic paraplegia

Kara E, Tucci A, Manzoni C, Lynch DS, Elpidorou M, Bettencourt C, Chelban V, Manole A, Hamed SA, Haridy NA, Federoff M, Preza E, Hughes D, Pittman A, Jaunmuktane Z, Brandner S, Xiromerisiou G, Wiethoff S, Schottlaender L, Proukakis C, Morris H, Warner T, Bhatia KP, Korlipara LV, Singleton AB, Hardy J, Wood NW, Lewis PA, Houlden H. Genetic and phenotypic characterization of complex hereditary spastic paraplegia. Brain. 2016 Jul;139(Pt 7):1904-18.

PubMed ID: 
27217339

Dystonia, Childhood Onset, With Optic Atrophy

Clinical Characteristics
Ocular Features: 

Optic atrophy is often observed during the first decade of life and has been noted as early as 15 months.  It may be congenital.  Nystagmus has been seen in some patients.

Systemic Features: 

Signs of motor dysfunction are seen in the first decade of life, and as early as 15 months of age.  Motor development may be mildly delayed.  Features are variable and include facial dystonia, myoclonus, dyskinesia, dysarthria, dysphagia, limb spasticity, and chorea-like movements all of which may progress.  Some patients lose independent ambulation but cognition is not affected.

Brain imaging reveals hyperintense T2-weighted signals in the basal ganglia.

Genetics

The transmission pattern in 5 reported families is consistent with autosomal recessive inheritance.  Biallelic mutations in the MECR gene (1p35) have been found in 7 affected individuals.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

MECR Mutations Cause Childhood-Onset Dystonia and Optic Atrophy, a Mitochondrial Fatty Acid Synthesis Disorder

Heimer G, Keratar JM, Riley LG, Balasubramaniam S, Eyal E, Pietikainen LP, Hiltunen JK, Marek-Yagel D, Hamada J, Gregory A, Rogers C, Hogarth P, Nance MA, Shalva N, Veber A, Tzadok M, Nissenkorn A, Tonduti D, Renaldo F; University of Washington Center for Mendelian Genomics., Kraoua I, Panteghini C, Valletta L, Garavaglia B, Cowley MJ, Gayevskiy V, Roscioli T, Silberstein JM, Hoffmann C, Raas-Rothschild A, Tiranti V, Anikster Y, Christodoulou J, Kastaniotis AJ, Ben-Zeev B, Hayflick SJ. MECR Mutations Cause Childhood-Onset Dystonia and Optic Atrophy, a Mitochondrial Fatty Acid Synthesis Disorder. Am J Hum Genet. 2016 Dec 1;99(6):1229-1244.

PubMed ID: 
27817865

Cataracts 34

Clinical Characteristics
Ocular Features: 

Two families with mutations in the FOXE3 associated with cataracts have been reported.  The lens opacities may be present at birth or found soon thereafter.  In 1 family with 5 affected sibs membranous cataracts were present along with corneal opacities, microcornea and nystagmus.  In another family, 7 sibs had posterior subcapsular cataracts but no other ocular findings.

Systemic Features: 

No systemic abnormalities were associated with the ocular findings.

Genetics

Homozygous mutations in the FOXE3 (1p33) gene segregated with the eye findings in the two families.  FOXE3 is a transcription gene and its mutations are responsible for a variety of ocular abnormalities.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Surgical cataract removal may be indicated.  Amblyopia is a risk and requires rehabilitation.

References
Article Title: 

FOXE3 contributes to Peters anomaly through transcriptional regulation of an autophagy-associated protein termed DNAJB1

Khan SY, Vasanth S, Kabir F, Gottsch JD, Khan AO, Chaerkady R, Lee MC, Leitch CC, Ma Z, Laux J, Villasmil R, Khan SN, Riazuddin S, Akram J, Cole RN, Talbot CC, Pourmand N, Zaghloul NA, Hejtmancik JF, Riazuddin SA. FOXE3 contributes to Peters anomaly through transcriptional regulation of an autophagy-associated protein termed DNAJB1. Nat Commun. 2016 Apr 6;7:10953. doi: 10.1038/ncomms10953. PubMed PMID: 27218149; PubMed Central PMCID: PMC4820811.

PubMed ID: 
27218149

Cone-Rod Dystrophy with Hearing Loss

Clinical Characteristics
Ocular Features: 

Patients note reduced vision in brightly-lit environments with onset in early adulthood and progressive central vision loss thereafter.   Nystagmus, photophobia, and dyschromatopsia may be present.  Younger individuals may complain of night blindness.  Visual fields show diffuse progressive suppression with relative sparing of selected areas such as the peripapillary region.  The ERG documents primary cone dystrophy but less involvement of the rods.  EOG testing in 4 patients showed reduced light-dark ratios.  Macular degeneration, attenuated vessels, subtle salt-and-pepper pigmentation, and spicular pigmentary deposits in the mid-periphery may be seen.

Systemic Features: 

The hearing loss is sensorineural in nature and can be progressive from its onset in childhood.

Genetics

This autosomal recessive disorder results from homozygous or compound heterozygous mutations in the CEPL78 (9q21.2) gene.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment for the basic condition has been reported.  Assistive hearing devices and tinted lenses could be helpful.

References
Article Title: 

Mutations in CEP78 Cause Cone-Rod Dystrophy and Hearing Loss Associated with Primary-Cilia Defects

Nikopoulos K, Farinelli P, Giangreco B, Tsika C, Royer-Bertrand B, Mbefo MK, Bedoni N, Kjellstrom U, El Zaoui I, Di Gioia SA, Balzano S, Cisarova K, Messina A, Decembrini S, Plainis S, Blazaki SV, Khan MI, Micheal S, Boldt K, Ueffing M, Moulin AP, Cremers FP, Roepman R, Arsenijevic Y, Tsilimbaris MK, Andreasson S, Rivolta C. Mutations in CEP78 Cause Cone-Rod Dystrophy and Hearing Loss Associated with Primary-Cilia Defects. Am J Hum Genet. 2016 Sep 1;99(3):770-6.

PubMed ID: 
27588451

CEP78 is mutated in a distinct type of Usher syndrome

Fu Q, Xu M, Chen X, Sheng X, Yuan Z, Liu Y, Li H, Sun Z, Li H, Yang L, Wang K, Zhang F, Li Y, Zhao C, Sui R, Chen R. CEP78 is mutated in a distinct type of Usher syndrome. J Med Genet. 2016 Sep 14. pii: jmedgenet-2016-104166. doi: 10.1136/jmedgenet-2016-104166.

PubMed ID: 
27627988

Neurodegeneration with Ataxia, Dystonia, and Gaze Palsy, Childhood-Onset

Clinical Characteristics
Ocular Features: 

Vertical gaze palsy has its onset between 7 and 15 years of age.   Nystagmus and oculomotor apraxia are often present.

Systemic Features: 

Onset of unsteadiness, gait ataxia, and cognitive decline are evident in the first or second decades of life.  Dysdiadokinesis, dysarthria, dysmetria, dystonia, athetotic movements, signs of Parkinsonism with tremor may also be present.  Some patients have a mild hearing loss.  Tissue from muscle biopsies are normal.  Brain imaging reveals cerebellar atrophy in some families and iron deposition in the basal ganglia in others.

Many patients are wheelchair-bound eventually.

Genetics

Homozygous mutations in the SQSTM1 gene (5q35.3) are responsible for this condition. 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported but physical therapy, speech therapy, and special education may be of benefit.

References
Article Title: 

Absence of the Autophagy Adaptor SQSTM1/p62 Causes Childhood-Onset Neurodegeneration with Ataxia, Dystonia, and Gaze Palsy

Haack TB, Ignatius E, Calvo-Garrido J, Iuso A, Isohanni P, Maffezzini C, Lonnqvist T, Suomalainen A, Gorza M, Kremer LS, Graf E, Hartig M, Berutti R, Paucar M, Svenningsson P, Stranneheim H, Brandberg G, Wedell A, Kurian MA, Hayflick SA, Venco P, Tiranti V, Strom TM, Dichgans M, Horvath R, Holinski-Feder E, Freyer C, Meitinger T, Prokisch H, Senderek J, Wredenberg A, Carroll CJ, Klopstock T. Absence of the Autophagy Adaptor SQSTM1/p62 Causes Childhood-Onset Neurodegeneration with Ataxia, Dystonia, and Gaze Palsy. Am J Hum Genet. 2016 Sep 1;99(3):735-43.

PubMed ID: 
27545679

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