autosomal recessive

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.

This nuclear gene plays a role in mitochondrial fatty acid synthesis.

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

Retinal Dystrophy With Or Without Extraocular Anomalies

Clinical Characteristics
Ocular Features: 

Progressive deterioration of rod and cone function is characteristic of this condition which is clinically manifest as some variation of pigmentary retinopathy.  Early (second decade) pigmentary changes resemble retinitis pigmentosa but in the fourth and fifth decades they resemble a peripheral pattern-like reticular dystrophy.  Central chorioretinal atrophy has been described in some patients.  The ERG responses are abnormal suggesting loss of the photoreceptors.

Systemic Features: 

Extraocular anomalies are highly variable ranging from a mild intellectual disability in some patients, to thyroid goiter and nodules, and primary ovarian insufficiency.  Sensorineural hearing loss was present in one family and one patient had pulmonary fibrosis.

Genetics

Homozygous missense mutations in the RCBTB1 gene (13q14) seem to be responsible for this condition.  Six families have been reported.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Isolated and Syndromic Retinal Dystrophy Caused by Biallelic Mutations in RCBTB1, a Gene Implicated in Ubiquitination

Coppieters F, Ascari G, Dannhausen K, Nikopoulos K, Peelman F, Karlstetter M, Xu M, Brachet C, Meunier I, Tsilimbaris MK, Tsika C, Blazaki SV, Vergult S, Farinelli P, Van Laethem T, Bauwens M, De Bruyne M, Chen R, Langmann T, Sui R, Meire F, Rivolta C, Hamel CP, Leroy BP, De Baere E. Isolated and Syndromic Retinal Dystrophy Caused by Biallelic Mutations in RCBTB1, a Gene Implicated in Ubiquitination. Am J Hum Genet. 2016 Aug 4;99(2):470-80.

PubMed ID: 
27486781

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

Coats Plus Syndrome

Clinical Characteristics
Ocular Features: 

Retinal telangiectasia and exudates (Coats disease) occur in association with intracranial cysts, calcifications and extraneurologic manifestations in this condition.  Coats disease lesions may also occur in Labrune syndrome (614561) and, of course, in isolation.

Whereas simple Coats disease almost exclusively occurs unilaterally and in males, both sexes and both eyes may have Coats retinal lesions in this syndrome.

Systemic Features: 

As a result of intracranial calcifications, leukodystrophy and brain cysts, patients have a variety of neurologic signs including spasticity, ataxia, dystonia, cognitive decline, and seizures.  Vascular ectasias may also occur throughout the body such as the intestines, stomach, and in the liver increasing the risk of GI bleeding and portal hypertension with anemia and thrombocytopenia.  Some individuals have sparse hair, abnormal pigmentation of the skin, and dysplastic nails as well. 

Some extraretinal features are also found in patients with dyskeratosis congenita (127550), and in Labrune syndrome (614561).

Genetics

This autosomal recessive pleotropic disorder results from compound heterozygous mutations in the CTC1 gene (17p13.1).  Several patients with mutations in STN1 have also been reported.

Most cases of simple Coats disease occur sporadically.  No associated locus or mutation has been found.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment for the general condition has been reported.  Specific treatment for the retinal vascular and brain lesions might be of benefit.  Physical therapy and special education should be considered in selected patients.

References
Article Title: 

Mutations in STN1 cause Coats plus syndrome and are associated with genomic and telomere defects. J Exp Med. 2016 Jul 25;213(8):1429-40

Simon AJ, Lev A, Zhang Y, Weiss B, Rylova A, Eyal E, Kol N, Barel O, Cesarkas K, Soudack M, Greenberg-Kushnir N, Rhodes M, Wiest DL, Schiby G, Barshack I, Katz S, Pras E, Poran H, Reznik-Wolf H, Ribakovsky E, Simon C, Hazou W, Sidi Y, Lahad A, Katzir H, Sagie S, Aqeilan HA, Glousker G, Amariglio N, Tzfati Y, Selig S, Rechavi G, Somech R. Mutations in STN1 cause Coats plus syndrome and are associated with genomic and telomere defects. J Exp Med. 2016 Jul 25;213(8):1429-40.

PubMed ID: 
27432940

Mutations in CTC1, encoding conserved telomere maintenance component 1, cause Coats plus

Anderson BH, Kasher PR, Mayer J, Szynkiewicz M, Jenkinson EM, Bhaskar SS, Urquhart JE, Daly SB, Dickerson JE, O'Sullivan J, Leibundgut EO, Muter J, Abdel-Salem GM, Babul-Hirji R, Baxter P, Berger A, Bonafe L, Brunstom-Hernandez JE, Buckard JA, Chitayat D, Chong WK, Cordelli DM, Ferreira P, Fluss J, Forrest EH, Franzoni E, Garone C, Hammans SR, Houge G, Hughes I, Jacquemont S, Jeannet PY, Jefferson RJ, Kumar R, Kutschke G, Lundberg S, Lourenco CM, Mehta R, Naidu S, Nischal KK, Nunes L, Ounap K, Philippart M, Prabhakar P, Risen SR, Schiffmann R, Soh C, Stephenson JB, Stewart H, Stone J, Tolmie JL, van der Knaap MS, Vieira JP, Vilain CN, Wakeling EL, Wermenbol V, Whitney A, Lovell SC, Meyer S, Livingston JH, Baerlocher GM, Black GC, Rice GI, Crow YJ. Mutations in CTC1, encoding conserved telomere maintenance component 1, cause Coats plus. Nat Genet. 2012 Jan 22;44(3):338-42.

PubMed ID: 
22267198

Retinitis Pigmentosa 76

Clinical Characteristics
Ocular Features: 

Onset of night blindness occurs early in the second decade of life.  Vision is in the range of 20/40 to 20/100 in the first decades worsens slowly but there is a wide range.  Some older individuals may have hand motion vision in at least one eye but some retain 20/40.  All patients have peripheral field restrictions and some have pallor of the optic disc.  Retinal vessels are attenuated.  Fundus pigmentation is usually abnormal with some combination of bone spicule and diffuse salt and pepper pigmentation.  The macula is usually involved with a flat fovea, cystoid macular edema, and chorioretinal atrophy.

Retinal thinning is seen on OCT.  The ERG can be flat but in some individuals the rod responses are primarily reduced.

Systemic Features: 

No systemic abnormalities have been associated.

Genetics

Homozygous or compound heterozygous mutations in the POMGNT1 gene (1p34) are responsible for this disorder.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treeatment is available.

References
Article Title: 

Mutations in POMGNT1 cause non-syndromic retinitis pigmentosa

Xu M, Yamada T, Sun Z, Eblimit A, Lopez I, Wang F, Manya H, Xu S, Zhao L, Li Y, Kimchi A, Sharon D, Sui R, Endo T, Koenekoop RK, Chen R. Mutations in POMGNT1 cause non-syndromic retinitis pigmentosa. Hum Mol Genet. 2016 Apr 15;25(8):1479-88.

PubMed ID: 
26908613

Cataracts, Congenital, Intellectual Disability, Abnormal Striatum, and ADHD

Clinical Characteristics
Ocular Features: 

Cataracts (not further described) were described as congenital although the diagnosis was usually made early in the first decade of life.  One patient was diagnosed at the age of 8 years with glaucoma and a cloudy cornea of the left eye.  Another patient had cataract surgery.  Visual acuities have not been reported.

Systemic Features: 

Four members of a consanguineous Saudi family have been reported with growth and mental retardation, microcephaly, dystonia, and spasticity.  IQs in the range of 77-89 were reported.  Linguistic delay is common.  Dysarthria and decreased cognitive function are present.  MRIs revealed thinning of the lentiform nucleus and swelling of the caudate heads.  

Genetics

Homozygous mutations in the KCNA4 (11p14.1) (176266) gene are responsible for this disorder.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for the general condition.  Cataract surgery may be considered.

References
Article Title: 

KCNA4 deficiency leads to a syndrome of abnormal striatum, congenital cataract and intellectual disability

Kaya N, Alsagob M, D'Adamo MC, Al-Bakheet A, Hasan S, Muccioli M, Almutairi FB, Almass R, Aldosary M, Monies D, Mustafa OM, Alyounes B, Kenana R, Al-Zahrani J, Naim E, Binhumaid FS, Qari A, Almutairi F, Meyer B, Plageman TF, Pessia M, Colak D, Al-Owain M. KCNA4 deficiency leads to a syndrome of abnormal striatum, congenital cataract and intellectual disability. J Med Genet. 2016 Aug 31. pii: jmedgenet-2015-103637. doi: 10.1136/jmedgenet-2015-103637. [Epub ahead of print].

PubMed ID: 
27582084

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: 

Mitochondrial DNA Depletion Syndrome 1

Clinical Characteristics
Ocular Features: 

Progressive external ophthalmoplegia has an adult onset, usually in the late second or early third decade of life.  Ptosis is commonly present as well.

Systemic Features: 

This condition has been called a mitochondrial neurogastrointestinal encephalopathy (MNGIE).  Gastrointestinal problems are among the most disabling with poor absorption of foodstuffs leading to weight loss, marked cachexia, and chronic malnutrition.  Added to this are gastroparesis, constipation, vomiting, and intermittent diarrhea with abdominal pain.  Many individuals develop diverticulosis and diverticulitis that may lead to intestinal perforations.  The combined intestinal dysfunctions can lead to signs of intestinal pseudoobstruction.

Many patients have a progressive sensorineural hearing loss.  Leukoencephalopathy, sensorimotor peripheral neuropathy, and sometimes mild proximal limb weakness may be present.

Genetics

Homozygous and compound heterozygous mutations in the TYMP gene (22q13.33) are responsible for this autosomal recessive disorder.  This nuclear gene is active in the maintainence of mitochondrial DNA.  When the gene is dysfunctional, the mitochondria can be depleted to a variable extent and they may contain multiple deletions and point mutations.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no effective treatment for the overall condition.  Nutritionists can provide important advice on diet to maintain good nutrition.  Regular monitoring by gastroenterologists is important.  Perforations of the bowels require prompt surgical repair.  

References
Article Title: 

Mitochondrial neurogastrointestinal encephalomyopathy: an autosomal recessive disorder due to thymidine phosphorylase mutations

Nishino I, Spinazzola A, Papadimitriou A, Hammans S, Steiner I, Hahn CD, Connolly AM, Verloes A, Guimaraes J, Maillard I, Hamano H, Donati MA, Semrad CE, Russell JA, Andreu AL, Hadjigeorgiou GM, Vu TH, Tadesse S, Nygaard TG, Nonaka I, Hirano I, Bonilla E, Rowland LP, DiMauro S, Hirano M. Mitochondrial neurogastrointestinal encephalomyopathy: an autosomal recessive disorder due to thymidine phosphorylase mutations. Ann Neurol. 2000 Jun;47(6):792-800.

PubMed ID: 
10852545

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