synechiae

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: 

Norrie Disease

Clinical Characteristics
Ocular Features: 

Norrie disease often presents at birth or soon thereafter with leukocoria.  There may be no response to light even at this early stage.  Microphthalmos, iris atrophy, and synechiae are often noted as well.  The posterior chamber contains a whitish-yellow mass associated with retinal folds and sometimes retinal detachment (pseudoglioma).  The vitreous may appear membranous and fibrovascular, often with traction on the retina.  Cataracts frequently develop early.  These signs may be unilateral or bilateral.  Corneal abnormalities such as opacities or sclerocornea may be present.  The mass in the posterior pole has to be distinguished from a retinoblastoma but the appearance may also resemble familial exudative vitreoretinopathy, Coats disease, persistent hyperplastic vitreous retinopathy, or retinopathy of prematurity.

Histology shows hemorrhagic necrosis of an undifferentiated glial mass.  The primary defect seems to lie in the neuroretina with absence of the ganglion cells and dysplasia of the remaining layers.  Many eyes become phthisical.

Systemic Features: 

Many individuals have growth and developmental delays with cognitive impairment and/or behavioral disorders (50%).  Frank psychoses have been reported in some patients.  Approximately 10% of patients have a chronic seizure disorder. Sensorineural deafness of some degree develops by the second decade in up to 100% of individuals.

Peripheral vascular disease (varicose veins, venous stasis ulcers, and erectile dysfunction) is present in nearly all men over the age of 50 years, perhaps the result of small vessel angiopathy.  Its age of onset is similar to that of the hearing deficit and the time course of progression is similar.

Genetics

This is an X-linked disorder as a result of mutations in the NDP gene (Xp11.4) encoding norrin.  Many mutations causing Norrie disease are novel or at least rare as might be expected for a disorder that leads to a marked reduction in reproductive fitness in males.  Carrier females usually do not have any evidence of disease.

Mutations in NDP also are responsible for a sex-linked form of familial exudative vitreoretinopathy, EVR2 (305390).  They have also been found in some cases of persistent hyperplastic primary vitreous and even in Coates' disease.  The latter conditions are usually present unilaterally, however, and some consider bilaterality to be a characteristic of NDP-related retinopathies.

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

No effective treatment is available.

References
Article Title: 

Mutations in the Norrie disease gene

Schuback DE, Chen ZY, Craig IW, Breakefield XO, Sims KB. Mutations in the Norrie disease gene. Hum Mutat. 1995;5(4):285-92.

PubMed ID: 
7627181

Axenfeld-Rieger Anomaly, Plus

Clinical Characteristics
Ocular Features: 

This rare disorder has ocular features of Rieger anomaly with significant systemic features but different than those found in the Axenfeld-Rieger syndrome.  The iris is hypoplastic and the pupil may be distorted secondary to anterior synechiae.  Schwalbe line is prominent.  There are no reports of glaucoma but this may be biased by the small number of patients reported.  Hypertelorism, prominent eyes and strabismus have been described.  Several patients have had absence of the extraocular muscles.

Systemic Features: 

Hypotonia, lax joints, midface hypoplasia, prominent forehead, and short stature have been described.  Some, but not all patients have a degree of psychomotor retardation.  Mild hearing impairment has been reported.

Genetics

This is likely an autosomal dominant disorder in which mutations of the PITX2 and FOXC1 genes common in Axenfeld-Rieger syndrome have been ruled out.  No locus has been identified.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No treatment is available.

References
Article Title: 

Nanophthalmos with Retinopathy

Clinical Characteristics
Ocular Features: 

This is a rare syndrome consisting of a pigmentary degeneration of the retina in association with nanophthalmos.  The globe is small with a thickened choroid and sclera and the macula becomes atrophic later in life. Some patients have cystic macular changes early without fluorescein leakage.  The anterior chamber is shallow, the angle is narrow, and the cornea may be small leading to angle closure glaucoma in most patients.  Extensive anterior and posterior synechiae can be seen.  The retina has a postequatorial bone spicule pattern of pigmentation with narrowing of arterial vessels.  Hyperopia is usually present and nightblindness may be noted in the first decade of life.  The ERG early shows loss of rod function and progression of the retinal disease subsequently leads to extinction of all rod and cone responses by midlife.  The EOG may be subnormal and visual fields are severely constricted.  Pallor and crowding of the optic nerve are common.  The vitreous may contain prominent fibrils and fine white granules.  Visual acuity is often 20/200 or worse.

Systemic Features: 

No systemic abnormalities have been reported.

Genetics

This is likely an autosomal recessive disorder based on frequent parental consanguinity and sibships with multiple affected individuals of both sexes.  However, the first reported family in 1958 with 13 affected individuals in 4 generations suggested autosomal dominant inheritance. No molecular defect has been identified.

This may be the same disorder as microphthalmia with retinitis pigmentosa (611040) in which so far no molecular mutation has been identified. 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Narrow angles with shallow anterior chamber depth should be treated with prophylactic iridotomies.

References
Article Title: 
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