pigmentary retinopathy

Usher Syndrome Type IV

Clinical Characteristics
Ocular Features: 

Nyctalopia is a complaint in adults in by midlife but most individuals deny visual symptoms prior to the 5th decade.  Perimetry reveals a ring-shaped scotoma extending from the paracentral area to the midperiphery (5 to 30 degrees).  Full-field ERGs show decreased photoreceptor responses by the 5th decade or late with the rods more severely affected than the cones.  Some dyschromatopsia is usually present.  Patients have a significant and progressive loss of visual acuity.  Ring-shaped areas of retinal pigment atrophy may extend from the pericentral area to the temporal arcades with relative sparing of the fovea early but older individuals have foveal degeneration as well.  The Arden EOG ratio is usually lower than normal.

Systemic Features: 

Five individuals in three Yemenite Jewish families have been described with this type of Usher syndrome.  A neurosensory hearing loss is present by midlife but no other systemic signs have been reported. 

Genetics

Homozygosity of a missense mutation in the ARSG gene (17q24.2) is responsible for this condition.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No specific treatment for this condition is available.  However, assistive hearing devices such as cochlear implants and corrective lenses with appropriate tinting can be beneficial.

References
Article Title: 

Heimler Syndrome 1

Clinical Characteristics
Ocular Features: 

Some patients have mottling of the retinal pigment and features of macular dystrophy.

Systemic Features: 

Primary dentition seems to be normal but secondary teeth have generalized enamel hypoplasia.  Severe bilateral sensorineural hearing loss has been diagnosed in the first or second year of life.  The toenails have transverse ridges (Beau lines) and the fingernails exhibit leukonychia.

Due to the small number of reported families, there is some uncertainty regarding the specificity of the clinical features among the Heimler 1 and Heimler 2 syndromes.

Genetics

Biallelic mutations in the PEX1 gene (7q21.2) are responsible for this syndrome.

Heimler Syndrome 2 (616617) seems to be a unique disorder of peroxisome biogenesis resulting from biallelic mutations in the PEX6 gene.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Spectrum of PEX1 and PEX6 variants in Heimler syndrome

Smith CE, Poulter JA, Levin AV, Capasso JE, Price S, Ben-Yosef T, Sharony R, Newman WG, Shore RC, Brookes SJ, Mighell AJ, Inglehearn CF. Spectrum of PEX1 and PEX6 variants in Heimler syndrome. Eur J Hum Genet. 2016 Nov;24(11):1565-1571.

PubMed ID: 
27302843

Heimler Syndrome Is Caused by Hypomorphic Mutations in the Peroxisome-Biogenesis Genes PEX1 and PEX6

Ratbi I, Falkenberg KD, Sommen M, Al-Sheqaih N, Guaoua S, Vandeweyer G, Urquhart JE, Chandler KE, Williams SG, Roberts NA, El Alloussi M, Black GC, Ferdinandusse S, Ramdi H, Heimler A, Fryer A, Lynch SA, Cooper N, Ong KR, Smith CE, Inglehearn CF, Mighell AJ, Elcock C, Poulter JA, Tischkowitz M, Davies SJ, Sefiani A, Mironov AA, Newman WG, Waterham HR, Van Camp G. Heimler Syndrome Is Caused by Hypomorphic Mutations in the Peroxisome-Biogenesis Genes PEX1 and PEX6. Am J Hum Genet. 2015 Oct 1;97(4):535-45.

PubMed ID: 
26387595

Macular dystrophy in Heimler syndrome

Lima LH, Barbazetto IA, Chen R, Yannuzzi LA, Tsang SH, Spaide RF. Macular dystrophy in Heimler syndrome. Ophthalmic Genet. 2011 Jun;32(2):97-100.

PubMed ID: 
21366429

Myopathy, Mitochondrial Anomalies, and Ataxia

Clinical Characteristics
Ocular Features: 

Ocular findings are variable.  One of three individuals with compound heterozygous mutations had a pigmentary retinopathy with pallor of the optic nerve but no visual abnormalities.  Her sister had only optic nerve pallor.  The eyes are described as "small" and "close-set".

No ocular findings were reported for the family with autosomal dominant inheritance.

Systemic Features: 

Ataxia, short stature, and gait difficulties from an early age are consistent findings.  Some patients are never able to walk.  Motor development is generally delayed.  Truncal and limb ataxia is a feature.  Some degree of intellectual disability is generally present and speech is often delayed.  

The face is long with a myopathic appearance.  Both micrognathia and a prominent jaw may be seen.  The palate is highly arched.  Patients are described as hypotonic and there is generalized muscle weakness both proximal and distal.  Distal sensory impairment has been described in the family with presumed dominant inheritance and there may be psychiatric symptoms of anxiety, depression, and schizophrenia.  Dysmetria with dysdiadochokinesis is often present and a fine intention tremor has been observed.

Mitochondria in fibroblasts exhibit abnormal dynamics and occur in a fragmented network.  Muscle biopsies reveal changes consistent with myopathy.  Serum creatine kinase may be elevated.

Genetics

Compound heterozygous mutations in the MSTO1 gene (1q22) have been found in two families with 3 affected individuals suggesting autosomal recessive inheritance.  In a third family, heterozygous mutations in the same gene were found in a mother and 3 of her adult children, consistent with autosomal dominant transmission.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Neurodevelopmental Disorder, Mitochondrial, with Abnormal Movements and Lactic Acidosis

Clinical Characteristics
Ocular Features: 

Optic atrophy is sometimes present.  Nystagmus, and strabismus are seen in some patients.  A pigmentary retinopathy was found in one individual.

Systemic Features: 

This is a clinically heterogeneous disorder with extensive neurological deficits.  Patients have feeding and swallowing difficulties from the neonatal period.  There is intrauterine growth retardation and postnatally patients usually exhibit psychomotor delays and intellectual disabilities.  Some develop seizures and few achieve normal developmental milestones.  Axial hypotonia is present from early infancy and most patients have muscle weakness and atrophy.  However, there may be spastic quadriplegia which is often associated with dysmetria, tremor, and athetosis.  Ataxia eventually develops in most patients. 

Brain imaging shows cerebral and cerebellar atrophy, enlarged ventricles, white matter defects, and delayed myelination. 

Incomplete metabolic studies suggest there may be abnormalities in mitochondrial oxidative phosphorylation activity in at least some tissues.  Most patients have an elevated serum lactate.

Death in childhood is common.

Genetics

Homozygous and compound heterozygous mutations in the WARS2 gene have been found in several families with this condition.  The considerable variation in the phenotype may at least partially be explained by the fact that an additional variant in the W13G gene is sometimes present which impairs normal localization of the WARS2 gene product within mitochondria.

The transmission pattern in several families is consistent with autosomal recessive inheritance.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported for the general condition.

References
Article Title: 

Biallelic variants in WARS2 encoding mitochondrial tryptophanyl-tRNA synthase in six individuals with mitochondrial encephalopathy

Wortmann SB, Timal S, Venselaar H, Wintjes LT, Kopajtich R, Feichtinger RG, Onnekink C, Muhlmeister M, Brandt U, Smeitink JA, Veltman JA, Sperl W, Lefeber D, Pruijn G, Stojanovic V, Freisinger P, V Spronsen F, Derks TG, Veenstra-Knol HE, Mayr JA, Rotig A, Tarnopolsky M, Prokisch H, Rodenburg RJ. Biallelic variants in WARS2 encoding mitochondrial tryptophanyl-tRNA synthase in six individuals with mitochondrial encephalopathy. Hum Mutat. 2017 Dec;38(12):1786-1795.

PubMed ID: 
28905505

Retinitis Pigmentosa 80

Clinical Characteristics
Ocular Features: 

Night blindness is an early symptom which may be noted in early childhood.  Vision loss can be documented in early childhood and progressively worsens to hand motions or light perception by the 3rd to 5th generation.  The fundus appearance has been described as normal in 1-year old patients but retinal pigmentary changes and arteriolar changes are evident in some children by the age of 2 years.  Typical bone spicule pigmentary changes have been described in some older patients.  Staring at lights (photophilia) has been noted in children under 1 year of age while eye-rubbing (oculodigital sign) may be seen soon thereafter.  Nystagmus is often present.

ERG responses are greatly diminished or nonrecordable.  Rods are more severely affected than cones.  OCT shows loss of inner and outer segments of photoreceptors.

Systemic Features: 

Systemic signs seem variable but full evaluations have not been done in all patients.  Mild developmental delay has been reported in some individuals and significant childhood onset hearing loss has been documented in at least one person.  Radiography of the hands revealed cone-shaped phalangeal epiphyses in 5 probands and one proband had short fingers in one study.

Genetics

Homozygous or compound heterozygous mutations in the IFT140 gene (16p13.3) segregates with the phenotype as expected for an autosomal recessive disorder.

The same gene is mutated in Short-Rib Thoracic Dysplasia 9 (266920) in which similar digital and retinal changes are seen.  However, renal, hepatic, and additional skeletal disease are also present.  These may be the same conditions pending further elucidation of the phenotypes.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported for the general disorder.  However, low vision aids should be offered to young people, especially during school years.

References
Article Title: 

Retinal Dystrophy with or without Macular Staphyloma

Clinical Characteristics
Ocular Features: 

Few patients have had complete eye studies and physical findings are seemingly limited to the eye.  Patients complain of progressively decreasing vision as early as the first decade of life.  Abnormal retinal findings may be present by the second decade and maybe earlier.  The RPE can appear mottled and the retinal vessels are attenuated.  Retinal pigment clumping occurs later.  Night blindness and visual field constriction occur.  Cone and flicker ERGs may be nonrecordable while rod and flash ERGs are reduced consistent with a rod-cone dystrophy.  The retinal lamination has been described as abnormal on OCT in some individuals.

Macular staphylomas have been described in three unrelated offspring of consanguineous parents.

Vision loss is severe with legal blindness by midlife and one patient lost light perception by 40 years of age.  

Systemic Features: 

No consistent systemic abnormalities have been reported.

Genetics

Homozygous or compound heterozygous mutations in the C21orf2 gene (21q22.3) are the cause of this autosomal recessive syndrome.

Homozygous or heterozygous mutations in the same gene are responsible for axial spondylometaphyseal dysplasia (602271).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Retinitis Pigmentosa With or Without Skeletal Anomalies

Clinical Characteristics
Ocular Features: 

Downward slanting lid fissures may be detectable at birth as part of the general craniofacial dysmorphism.  Some degree of night blindness causes symptoms by the second decade of life and constricted visual fields with pigmented retinopathy and vessel narrowing can be detected.  The ERG shows reduced or absent responses.  The retinal phenotype is progressive.   

Systemic Features: 

Most but not all patients have skeletal anomalies.  Nonspecific craniofacial dysmorphology features are frequently present including frontal bossing, macrocephaly, low-set ears, large columella, hypoplastic nares, and malar hypoplasia.  A short neck, brachydactyly, and overall shortness of stature are often present.  Some individuals have nail dysplasia.  The proximal femoral metaphyses sometimes show chondrodysplasia.

There is often some degree of intellectual disability and there may be delays in speech, feeding, and walking.

Genetics

This disorder results from homozygous or compound heterozygous mutations in the CWC27 gene (5q12.3).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No general treatment has been reported.  Low vision aids and night vision devices may be helpful, especially for educational activities.

References
Article Title: 

Mutations in the Spliceosome Component CWC27 Cause Retinal Degeneration with or without Additional Developmental Anomalies

Xu M, Xie YA, Abouzeid H, Gordon CT, Fiorentino A, Sun Z, Lehman A, Osman IS, Dharmat R, Riveiro-Alvarez R, Bapst-Wicht L, Babino D, Arno G, Busetto V, Zhao L, Li H, Lopez-Martinez MA, Azevedo LF, Hubert L, Pontikos N, Eblimit A, Lorda-Sanchez I, Kheir V, Plagnol V, Oufadem M, Soens ZT, Yang L, Bole-Feysot C, Pfundt R, Allaman-Pillet N, Nitschke P, Cheetham ME, Lyonnet S, Agrawal SA, Li H, Pinton G, Michaelides M, Besmond C, Li Y, Yuan Z, von Lintig J, Webster AR, Le Hir H, Stoilov P; UK Inherited Retinal Dystrophy Consortium., Amiel J, Hardcastle AJ, Ayuso C, Sui R, Chen R, Allikmets R, Schorderet DF. Mutations in the Spliceosome Component CWC27 Cause Retinal Degeneration with or without Additional Developmental Anomalies. Am J Hum Genet. 2017 Apr 6;100(4):592-604.

PubMed ID: 
28285769

Aniridia 2

Clinical Characteristics
Ocular Features: 

A 17-year-old male with this condition was diagnosed at the age of two years with bilateral iris hypoplasia.  Cataracts were seen at the age of 17 years.  There was no foveal depression.

In a 5 generation Chinese family there were additional signs including optic atrophy, ectopia lentis, pigmentary retinopathy, and 'dysplasia' of the trabecular meshwork in 5 members.

Systemic Features: 

No systemic abnormalities have been reported.  A single extensively studied patient, who had no developmental problems, was normal by renal ultrasound, audiometric studies, and neurologic evaluations.

Genetics

Autosomal dominant aniridia is the result of PAX6 (a transcription regulator gene) dysfunction.  In the majority of cases there are mutations in the PAX6 gene itself as in AN1.  There are reports, however, of familial aniridia in which direct PAX6 mutations have been excluded.  Two additional forms of aniridia in which there are alterations in genes that modulate the expression of PAX6 have been reported.  AN2 described here with mutations in ELP4, a nucleotide variant within an intron of the ELP4 gene (11p13) located distal to the 3-prime end of the PAX6 gene, plus AN3 (617142) with mutations in TRIM44.  Both ELP4 and TRIM44 are regulators of the PAX6 transcription gene.

Aniridia 2 has been reported in one patient with a nucleotide variant within an intron of the ELP4 gene (11p13) located distal to the 3-prime end of the PAX6 gene.  The gene product is a cis-regulatory enhancer.  

Other evidence for aniridia resulting from regulatory modification of PAX6 gene function comes from families in which there are structural alterations such as deletions in chromosome 11, downstream of the PAX6 gene location.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Treatment has not been reported.

References
Article Title: 

A deletion 3' to the PAX6 gene in familial aniridia cases

D'Elia AV, Pellizzari L, Fabbro D, Pianta A, Divizia MT, Rinaldi R, Grammatico B, Grammatico P, Arduino C, Damante G. A deletion 3' to the PAX6 gene in familial aniridia cases. Mol Vis. 2007 Jul 23;13:1245-50.
 

PubMed ID: 
17679951

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

Retinitis Pigmentosa 42

Clinical Characteristics
Ocular Features: 

The fundus phenotype of retinitis pigmentosa appears late.  Night vision difficulties are prominent symptoms but the age of onset is unknown. Reduction in visual acuity is variable and is usually not manifest until 50 years of age but it may remain near normal or in that range for another decade or two.  Concentric constriction (within 10-20 central degrees) in peripheral fields can be a presenting symptom and may not appear until age 65 years of age.  Patches of visual field retention can sometimes be demonstrated in the periphery.  Rod and cone full field ERG amplitudes are substantially reduced

Systemic Features: 

None.

Genetics

Heterozygous mutations in KLHL7 (7p15.3) segregate with the clinical phenotype.

Homozygous mutations in the KLHL7 gene cause cold-induced sweating syndrome 3 (CISS3) (617055).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

None known.

References
Article Title: 

Mutations in a BTB-Kelch protein, KLHL7, cause autosomal-dominant retinitis pigmentosa

Friedman JS, Ray JW, Waseem N, Johnson K, Brooks MJ, Hugosson T, Breuer D, Branham KE, Krauth DS, Bowne SJ, Sullivan LS, Ponjavic V, Granse L, Khanna R, Trager EH, Gieser LM, Hughbanks-Wheaton D, Cojocaru RI, Ghiasvand NM, Chakarova CF, Abrahamson M, Goring HH, Webster AR, Birch DG, Abecasis GR, Fann Y, Bhattacharya SS, Daiger SP, Heckenlively JR, Andreasson S, Swaroop A. Mutations in a BTB-Kelch protein, KLHL7, cause autosomal-dominant retinitis pigmentosa. Am J Hum Genet. 2009 Jun;84(6):792-800.

PubMed ID: 
19520207

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