corneal opacities

Galloway-Mowat Syndrome

Clinical Characteristics
Ocular Features: 

Microphthalmia, hypertelorism, epicanthal folds and ptosis are prominent ocular features.  Other manifestations include corneal opacities, cataracts, and optic atrophy.  Nystagmus of a roving nature is seen in all individuals and is usually present at birth.  There is evidence of visual impairment in more than 90% of individuals.  Features of an anterior chamber dysgenesis such as a hypoplastic iris are sometimes present.

The ocular features of this syndrome have not been fully described.

Systemic Features: 

Infants are born with low birth weight due to intrauterine growth retardation and there is often a history of oligohydramnios.  Newborns are often floppy and hypotonic although spasticity may develop later.  A small midface and microcephaly (80%) with a sloping forehead and a flat occiput are frequently evident.  The ears are large, floppy, and low-set while the hard palate is highly arched and the degree of micrognathia can be severe.  The fists are often clenched and the digits can appear narrow and arachnodactylous.  Hiatal hernias may be present.

Many patients develop features of the nephrotic syndrome in the first year of life with proteinuria and hypoalbuminemia due to glomerular kidney disease and renal system malformations.  Renal biopsies show focal segmental glomerulosclerosis in the majority of glomeruli.

Evidence of abnormal neuronal migration with brain deformities such as cystic changes, porencephaly, encephalomalacia, and spinal canal anomalies have been reported.  MRI imaging shows diffuse cortical and cerebellar atrophy atrophic optic nerves, and thinning of the corpus callosum.  The normal striated layers of the lateral geniculate nuclei are obliterated.  The cerebellum shows severe cellular disorganization with profound depletion of granule cells and excessive Bergmann gliosis.  The vermis is shortened. 

Multifocal seizures are sometimes (40%) seen in infancy and early childhood and the EEG generally shows slowed and disorganized backgound and sometimes a high-voltage hypsarrhythmia.  The degree of psychomotor delay and intellectual disability is often severe.   Most patients are unable to sit independently (90%), ambulate (90%), or make purposeful hand movements (77%).  The majority (87%) of children have extrapyramidal movements and a combination of axial dystonia and limb chorea.  Mean age of death is about 11 years (2.7 to 28 years in one series) and most die from renal failure.

Genetics

Gallaway-Mowat syndrome is likely a spectrum of disease.  Homozygous mutations in the WDR73 gene (15q25) are responsible for one form of this syndrome.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no treatment for GAMOS.

References
Article Title: 

Recessive nephrocerebellar syndrome on the Galloway-Mowat syndrome spectrum is caused by homozygous protein-truncating mutations of WDR73

Jinks RN, Puffenberger EG, Baple E, Harding B, Crino P, Fogo AB, Wenger O, Xin B, Koehler AE, McGlincy MH, Provencher MM, Smith JD, Tran L, Al Turki S, Chioza BA, Cross H, Harlalka GV, Hurles ME, Maroofian R, Heaps AD, Morton MC, Stempak L, Hildebrandt F, Sadowski CE, Zaritsky J, Campellone K, Morton DH, Wang H, Crosby A, Strauss KA. Recessive nephrocerebellar syndrome on the Galloway-Mowat syndrome spectrum is caused by homozygous protein-truncating mutations of WDR73. Brain. 2015 Aug;138(Pt 8):2173-90.  PubMed PMID: 26070982.

PubMed ID: 
26070982

Loss-of-Function Mutations in WDR73 Are Responsible for Microcephaly and Steroid-Resistant Nephrotic Syndrome: Galloway-Mowat Syndrome

Colin E, Huynh Cong E, Mollet G, Guichet A, Gribouval O, Arrondel C, Boyer O, Daniel L, Gubler MC, Ekinci Z, Tsimaratos M, Chabrol B, Boddaert N, Verloes A, Chevrollier A, Gueguen N, Desquiret-Dumas V, Ferre M, Procaccio V, Richard L, Funalot B, Moncla A, Bonneau D, Antignac C. Loss-of-Function Mutations in WDR73 Are Responsible for Microcephaly and Steroid-Resistant Nephrotic Syndrome: Galloway-Mowat Syndrome. Am J Hum Genet. 2014 Dec 4;95(6):637-48..

PubMed ID: 
25466283

Familial Exudative Vitreoretinopathy, EVR5

Clinical Characteristics
Ocular Features: 

The clinical picture is highly heterogeneous.  Abnormal peripheral vascularization of the retina is generally evident and most individuals have retinal exudates.  The amount of exudation is dependent to some extent upon age.  Fluorescein angiography may demonstrate incomplete vascularization of the peripheral retina.  The ocular phenotype can resemble retinal dysplasia.  Occasional infants can have severe retinal disease and may be considered blind but many individuals have minimal disease and retain good vision into adulthood.  Unfortunately, traction retinal detachments may develop at any time and are responsible for blindness in some patients. 

Cataracts are sometimes present. Ectopic pupils, lack of well-defined pupillary collarettes, remnants of the fetal vascular stalk, and shallowing of the anterior chamber have been noted in several patients.  Microphthalmia and corneal opacities may also be present.  Horizontal nystagmus can be seen in severely affected babies before one month of age.

Systemic Features: 

No systemic features have been reported.

Genetics

This disorder can be inherited in an autosomal dominant pattern as the result of heterozygous mutations in the TSPAN12 gene (7q31.31).  However, individuals with more severe disease may have homozygous mutations in this gene. 

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

This disorder can be inherited in an autosomal dominant pattern as the result of heterozygous mutations in the TSPAN12 gene (7q31.31).  However, individuals with more severe disease may have homozygous or compound heterozygous mutations in this gene. 

References
Article Title: 

Retinal Nonattachment, Congenital

Clinical Characteristics
Ocular Features: 

The common denominator in this condition is, of course, congenital nonattachment of the retina.  Many eyes are small as well.  Some patients in addition have a vascularized hyperplastic vitreous and often present with blindness and a congenital leukocoria.  Many at some stage have lens opacification, as well as glaucoma and anterior chamber anomalies including anterior synechiae and some degree of corneal opacification.  These signs are often progressive beginning in childhood.  Pendular nystagmus and esotropia are common.  MRI studies reveal optic nerves and the chiasm that are either absent or abnormally small.

Systemic Features: 

This condition is nonsyndromic and has no systemic abnormalities.

Genetics

Congenital retinal nonattachment consists of a group of sometimes familial conditions for which no responsible gene has been identified.  In a genomic study of 21 consanguineous NCRNA Pakistani families 3 had mutations in ATOH7 and 10 had mutations in familial exudative vitreoretinopathy genes.  Genotyping did not reveal associated mutations in the remaining 38% of these families. It is likely that multiple entities are represented but until the molecular etiologies are identified, no more specific classification is possible.

Studies in mice document that the Atoh7 gene is important to retinal ganglion cell neurogenesis.  In humans, both autosomal recessive PHPV and congenital nonattachment of the retina are associated with microsatellite linkage and haplotype matching to a region at 10q21 adjacent to the ATOH7 gene but so far no causative mutation has been found in this region.  However, studies in large consanguineous kindreds in which a deleted DNA segment adjacent to ATOH7 segregated with the NCRNA phenotype suggest that a transcription regulator may be at fault in the timing and level of ATOH7 expression.

The disorder known as persistent hyperplastic primary vitreous is generally not considered hereditary since it usually occurs unilaterally and sporadically.  It is sometimes found in association with a number of syndromal conditions as well.  However, it has also been reported in familial patterns consistent with both autosomal recessive and autosomal dominant patterns.  DNA mapping of individuals with bilateral disease found in a consanguineous Pakistani kindred with presumed autosomal recessive disease suggests that a locus at 10q11-q21 may be responsible.

Evidence for autosomal dominant inheritance of persistent hyperplastic primary vitreous comes from rare families with an apparent vertical transmission of the condition.

Congenital nonattachment of the retina is also seen in the osteoporosis-pseudoglioma syndrome (250770).  However, this is a syndromal disorder with neurologic and joint disease in addition to porotic, thin, fragile bones (sometimes called the ocular form of osteogenesis imperfecta) resulting from mutations in LRP5 on chromosome 11.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

With rare exceptions, the retina cannot be reattached successfully and phthisis with blindness is the usual outcome.

References
Article Title: 

Cataracts, CRYAA Mutations

Clinical Characteristics
Ocular Features: 

This seems to be a clinically heterogeneous group of lens opacities all due to mutations in the crystallin gene CRYAA.  Some patients also have colobomas and may have microcornea and corneal opacities.  The lens opacities are usually bilateral but there is considerable asymmetry in their morphology.  Opacities may be nuclear, polar, cortical, sutural, embryonal, and anterior subcapsular in location.  The cataracts are often present at birth.

Systemic Features: 

Systemic disease is absent.

Genetics

A variety of mutations in the CRYAA (21q22.3) have been reported in a several ethnic groups.  Most pedigrees are consistent with autosomal dominant inheritance but autosomal recessive inheritance has been suggested in other families.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

Lens extraction may be necessary.

References
Article Title: 

Microphthalmia, Syndromic 7

Clinical Characteristics
Ocular Features: 

Microphthalmia and rarely clinical anophthalmia are the ocular hallmarks of this disorder.  Corneal leukomas and some degree of sclerocornea are usually present as well.  Orbital cysts have been observed.  Other less consistent findings include iridocorneal adhesions, glaucoma, microcornea, cataracts, aniridia, persistence of the anterior hyaloid artery and other vitreous opacities, and patchy hypopigmentation of the RPE.

Systemic Features: 

The skin on the nose, cheeks and neck has linear red rashes and scar-like lesions.  Biopsy of these has revealed smooth muscle hemartomata rather than simple dermal aplasia.  There may be some healing of the skin defects.  The corpus callosum is sometimes absent.  Diaphragmatic hernias are often present.  Cardiac abnormalities include hypertrophic cardiomyopathy, arrhythmias, and septal defects.   Preauricular pits and hearing loss have been found in some patients.  Patients may be short in stature and some have nail dysplasia.  GU and GI anomalies may be present.

Genetics

This is an X-linked dominant disorder with lethality in the hemizygous male.  Many patients (79%) have interstitial deletions of the Xp22.2 region of the X chromosome.  Sequence analysis of this region has revealed heterozygous point mutations in the HCCS gene (Xp22.2) in numerous other patients.  In several additional cases deleterious mutations have been found in the X-linked COX7B gene.  However, familial occurrence is uncommon.  X chromosome inactivation may be skewed with the abnormal X being inactive in virtually all cases. Several 46 XX males with this syndrome have been described.

Goltz syndrome (305600), also called focal dermal hypoplasia, may have similar skin and ocular findings but the limb anomalies are not found in the disorder described here.  Goltz syndrome (305600) is the result of mutations in PORCN at another locus on the X chromosome and is thus unrelated.

Other X-linked dominant disorders with lethality in hemizygous males and abnormalities in skin and the eye are Incontinentia pigmenti (308300) and Aicardi syndrome (304050).  The skin lesions and ocular anomalies are dissimilar to those in MLS and they often have far more severe CNS abnormalities.   Further, the mutation causing Aicardi is in the NEMO (IKBKG) gene at another location on the X chromosome.

Pedigree: 
X-linked dominant, mother affected
Treatment
Treatment Options: 

Treatment is organ-specific with repair of septal defects and diaphragmatic hernias.  Progressive orbital prosthetics should be considered in patients with blind, microphthalmic and clinically anophthalmic eyes.

References
Article Title: 

Microphthalmia with linear skin defects syndrome in a mosaic female infant with monosomy for the Xp22 region: molecular analysis of the Xp22 breakpoint and the X-inactivation pattern

Ogata T, Wakui K, Muroya K, Ohashi H, Matsuo N, Brown DM, Ishii T, Fukushima Y. Microphthalmia with linear skin defects syndrome in a mosaic female infant with monosomy for the Xp22 region: molecular analysis of the Xp22 breakpoint and the X-inactivation pattern. Hum Genet. 1998 Jul;103(1):51-6. Review.

PubMed ID: 
9737776

Oculoauricular Syndrome

Clinical Characteristics
Ocular Features: 

This rare malformation syndrome affects primarily the eyes and ears.  The globes are small and usually have colobomas of both anterior and posterior segments.  The corneas likewise are small and often have opacities.  The anterior segment is dysplastic with anterior and/or posterior synechiae.  Glaucoma may be present.  The lenses may be small and often become cataractous.  There is a progressive rod-cone dystrophy associated with a pigmentary retinopathy.  Chorioretinal lacunae have been seen in the equatorial region.  The retinal degeneration is progressive, beginning with rod dysfunction but followed by deterioration of all receptors.  The onset in early childhood results in poor vision and nystagmus. 

Systemic Features: 

The external ears are abnormal.  The earlobes may have colobomas or may be aplastic.  The intertragic notch is often underdeveloped.  Audiograms and vestibular function tests, however, show normal function and MRI of the middle and inner ears likewise reveals no anatomic abnormalities.       

Among the few patients reported, dental anomalies, spina bifida oculta, and mild dyscrania have been noted in individual patients.

Genetics

This rare disorder has been reported in only a few families.  Based on parental consanguinity and homozygosity of mutations in the HMX1 gene (4p16.1) in affected sibs, this is an autosomal recessive disorder.  In one family there was a homozygous 26 bp deletion and in another a homozygous missense mutation.  The parents are heterozygous for the deletion.

HMX1 is a homeobox gene and the deletion abolishes its function by establishing a stop codon at position 112.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for the extraocular malformations.  Glaucoma treatment and cataract surgery should be considered although permanent visual rehabilitation is unlikely given the progressive nature of the rod-cone dystrophy.

References
Article Title: 

Neuraminidase Deficiency

Clinical Characteristics
Ocular Features: 

A cherry red spot is may be seen in late childhood or early adolescence.  It occurs in nearly 100% of patients with type I while only 75% of type II patients have this feature possibly because their early death from the more severe systemic disease prevents full ascertainment.  Visual acuity is reduced, sometimes severely.  Some but not all individuals have corneal and lens opacities.  A subtle corneal haze has also been seen.  Nystagmus has been reported. 

Systemic Features: 

This is a neurodegenerative disorder with progressive deterioration of muscle and central nervous system functions.  Myoclonus, mental deterioration, hepatosplenomegaly, muscle weakness and atrophy are common.  The defect in neuraminidase activity leads to abnormal amounts of sialyl-oligosaccharides in the urine.  Spinal deformities such as kyphosis are common.  Deep tendon reflexes are exaggerated.  Ataxia and hearing loss may be present.  Coarse facies, a barrel chest, and short stature are characteristic.  Hepatic cells contain numerous vacuoles and numerous inclusions.

Sialidosis types I and II are both caused by mutations in the neuroaminidase gene.  Type I is associated with milder disease than type II which has an earlier age of onset and may present in infancy or even begin in utero.  Early death within two years of age is common in the congenital or infantile forms.  There is, however, significant variability in age of onset and the course of disease among types. 

Genetics

The sialidoses are autosomal recessive lysosomal storage disorders resulting from mutations in the NEU1 gene (6p21.3) which lead to an intracellular accumulation of glycoproteins containing sialic acid residues.  Both types I and II are caused by mutations in the same gene. 

Treatment
Treatment Options: 

Treatment is focused on symptom management. 

References
Article Title: 

Tyrosinemia, Type II

Clinical Characteristics
Ocular Features: 

Keratitis is the outstanding ocular manifestation but not all patients have corneal involvement.  Symptoms include photophobia, pain, tearing, and redness which may occur as early as one year of age.  Corneal neovascularization, ulceration and scarring may lead to decreased visual acuity.  Linear and star-like corneal opacities in the epithelium resembling dendrites (pseudodendritic keratitis) have been described together with thickening of the conjunctiva.  The corneal lesions do not stain.  The conjunctival epithelium, fibrocytes, and blood vessel endothelial cells contain an accumulation of large inclusion bodies and tyrosine crystal-like structures. 

Systemic Features: 

Hydroxyphenylpyruvic acid is elevated in the urine and serum tyrosine levels are increased as the result of a defect in tyrosine aminotransferase.  Some patients have severe mental and somatic retardation.  The palms and soles can have painful punctate keratosis which may extend to the digits.  Developmental milestones such as walking are often delayed.  The keratotic lesions may be up to 2 cm in size. 

Genetics

Tyrosinemia type II is an autosomal recessive disorder caused by mutations in the tyrosine aminotransferase (TAT) gene at 16q22.1-q22.3. 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

The hyperkeratosis and corneal opacities may improve with a diet low in phenylalanine and tyrosine but can recur after liberalization of the diet.  Benefits, if any, on CNS symptoms are unknown. 

References
Article Title: 

Mutation update, eleven novel mutations and description of five independent subjects with a novel founder mutation

Pena-Quintana L, Scherer G, Curbelo-Estevez ML, Jimenez-Acosta F, Hartmann B, Roche F, Meavilla-Olivas S, Perez-Cerda C, Garcia Segarra N, Giguere Y, Huppke P, Mitchell GA, Monch E, Trump D, Vianey-Saban C, Trimble ER, Vitoria-Minana I, Reyes-Suarez D, Ramirez-Lorenzo T, Tugores A. TYROSINEMIA TYPE II: Mutation update, eleven novel mutations and description of five independent subjects with a novel founder mutation. Clin Genet. 2017 Mar 3. doi: 10.1111/cge.13003. [Epub ahead of print].

PubMed ID: 
28255985

Sjogren-Larsson Syndrome

Clinical Characteristics
Ocular Features: 

The retina often has glistening white intraretinal dots which may be concentrated in the macula.  They have been found in 1 to 2 year old infants.  The macula may have ‘punched out’ lesions.  A pigmentary retinopathy is present in about 50% of patients and fluorescein angiography reveals a mottled hyperfluorescence. The cornea often has grayish stromal opacities that become vascularized, most commonly in the lower half.  Most patients have punctate keratitis resulting in marked photophobia.  Visual acuities can range from about 20/40 to finger counting.  The retinal changes may be progressive but EOG and ERG studies do not reveal abnormalities of retinal function.  VEPs though are often abnormal.  Ichthyosis may involve the lids and periorbital areas.

Systemic Features: 

The skin changes are present at birth and consist of an ichthyosiform erythroderma.  Hyperkeratosis is also present at birth and full blown ichthyosis develops during infancy.  The skin changes are most marked about the neck, flexion creases, and lower abdomen.  Scales in these areas are often darker than the surrounding skin.  Mental retardation may be mild to severe and spastic diplegia or quadriplegia is common but there is little evidence of progression.  There does not seem to be any correlation of age with the severity of neurological disease.

Genetics

Mutations in the ALDH3A2 gene (17p11.2) are responsible for this autosomal recessive disorder resulting in a deficiency of fatty aldehyde dehydrogenase. This can lead to long-chain fatty alcohol accumulation as demonstrated in the brain with proton magnetic resonance spectroscopy.

A form of Sjogren-Larsson syndrome with more severe neurologic signs is caused by recessive mutations in ELOVL4 (6p14,1),  Mutations in the same gene have been identified in patients with autosomal dominant Stargardt disease 3 (600110).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for this disorder but moisturizing skin treatments can be beneficial.

References
Article Title: 

Keratosis Follicularis Spinulosa Decalvans, X-Linked

Clinical Characteristics
Ocular Features: 

There is alopecia of the eyelashes and eyebrows.  The skin of the eyelids is thickened often with an associated chronic blepharitis followed by entropion (ectropion sometimes mentioned).  Photophobia and keratitis with 'corneal degeneration' are also features but it is unknown whether these are primary or secondary to trichiasis from the eyelid deformities.  The corneal findings usually precede the scarring alopecia of the scalp.

Systemic Features: 

Onset is in childhood.  Thickening of skin is generalized especially in the neck, ears, and the extremities with marked involvement of the palms and soles, especially in the calcaneal regions.  Scalp hair may be sparse, often in a streak pattern.  The follicles are inflamed and hyperkeratotic resulting in scarring alopecia.  Carriers have been reported to have dry skin with mild follicular hyperkeratosis and more extensive involvement of the soles.

Genetics

This is a rare disorder with genetic and clinical heterogeneity.  The majority of cases seem to be inherited in an X-linked recessive pattern secondary to mutations in the SAT1 gen located at Xp22.1. 

However, multigenerational families with male to male transmission have also been reported suggesting autosomal dominant inheritance (KFSD; 612843).  However, no associated mutations or loci have been reported for this condition.

 

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

Retinoids reduce the inflammatory component and lead to cessation of the scalp alopecia.  A decrease in photophobia has also been reported but the clinical basis for this is unknown.

References
Article Title: 

Gene dosage of the spermidine/spermine N(1)-acetyltransferase ( SSAT) gene with putrescine accumulation in a patient with a Xp21.1p22.12 duplication and keratosis follicularis spinulosa decalvans (KFSD)

Gimelli G, Giglio S, Zuffardi O, Alhonen L, Suppola S, Cusano R, Lo Nigro C, Gatti R, Ravazzolo R, Seri M. Gene dosage of the spermidine/spermine N(1)-acetyltransferase ( SSAT) gene with putrescine accumulation in a patient with a Xp21.1p22.12 duplication and keratosis follicularis spinulosa decalvans (KFSD). Hum Genet. 2002 Sep;111(3):235-41.

PubMed ID: 
12215835

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