cataracts

Familial Exudative Vitreoretinopathy, EVR1

Clinical Characteristics
Ocular Features: 

The basis for many of the ocular complications likely begins with incomplete development of the retinal vasculature.  Resulting retinal ischemia leads to neovascularization, vitreous hemorrhage and traction, and retinal folds, with some 20% going on to develop rhegmatogenous or traction detachments.  There is, however, considerable clinical variability, even within families, with some infants blind from birth whereas some (41%) adults have only areas of remaining avascularity or evidence of macular dragging.  In fact, some affected individuals are asymptomatic and diagnosed only as part of extensive family studies.  Intraretinal lipid is often seen.  Considerable asymmetry in the two eyes is common.  Secondary cataracts often occur and phthisis bulbi results in some patients.  The clinical picture is sometimes confused with retinopathy of prematurity.

Systemic Features: 

No systemic features have been associated with EVR1 disease.

Genetics

Familial exudative vitreoretinopathy is the name given to a clinically and genetically heterogeneous group of disorders caused by mutations in several genes.  Both autosomal dominant (EVR1 described here) plus EVR4 (601813) and X-linked inheritance (EVR2; 305390) have been reported with the former much more common.  Similarities in the clinical presentation of Congenital Nonattachment of the Retina may cause diagnotic confusion. 

Mutations in the frizzled-4 gene FZD4 (11q14-q21) have been associated with the EVR1 form of this disease inherited in an autosomal dominant pattern.  Retinopathy of prematurity can be called a phenocopy of FEVR.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Retinal, vitreal, and cataract surgery are indicated in appropriate cases.

References
Article Title: 

Peroxisome Biogenesis Disorder 1B (neonatal adrenoleukodystrophy)

Clinical Characteristics
Ocular Features: 

This peroxisomal disorder presents in the first year of life with both systemic and ocular features.  Night blindness is the major ocular feature and at least some have optic atrophy similar to the adult form.  Central acuity is reduced secondary to macular degeneration.  A pigmentary retinopathy is frequently present and often follows the appearance of whitish retinal flecks in the midperipheray.  Nystagmus and cataracts are common features.  Reduction or absence of ERG responses can be used in young children to document the retinopathy.  Blindness and deafness commonly occur in childhood.

Systemic Features: 

This disorder is classified as a leukodystrophy, or disease of white matter of the brain, associated with the breakdown of phytanic acid.  Ataxia and features of motor neuron disease are evident early.  Hepatomegaly and jaundice may also be early diagnostic features as bile acid metabolism is defective.  Infant hypotonia is often seen.  Nonspecific facial dysmorphism has been reported.  The ears are low-set and epicanthal folds are present.  The teeth are abnormally large and often have yellowish discoloration.  Postural unsteadiness is evident when patients begin walking.  Diagnosis can be suspected from elevated serum phytanic and pipecolic acid (in 20% of patients) or by demonstration of decreased phytanic acid oxidation in cultured fibroblasts.  Other biochemical abnormalities such as hypocholesterolemia, and elevated very long chain fatty acids and trihydroxycholestanoic acid are usually present.  Anosmia, developmental delays, and mental retardation are nearly universal features.  Early mortality in infancy or childhood is common.

Genetics

This is a genetically heterogeneous disorder of peroxisome biogenesis caused by mutations in at least three genes, PEX1 (7q21-q22), PEX2 (8q21.1), and PEX6 (22q11-21).  Each is inherited in an autosomal recessive pattern.  The mechanism of disease is different from the classic or adult Refsum disorder (266500) and some have debated whether the term ‘infantile Refsum disease’ is appropriate.

This disorder shares some clinical features with other peroxisomal disorders such as Zellweger syndrome (214100) and rhizomelic chondrodysplasia punctata (215100).  Zellweger syndrome (214100), neonatal adrenoleukodystrophy and infantile Refsum disease (601539) are now considered to be peroxisomal biogenesis or Zellweger spectrum disorders.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment is known.

References
Article Title: 

Rothmund-Thomson Syndrome

Clinical Characteristics
Ocular Features: 

Patients have been reported with juvenile and infantile cataracts.  Reported prevalence varies possibly because the diagnostic criteria have not been established and more than one disorder may be represented by the title.  Rothmund (an ophthalmologist) originally reported two families of 5 children in which lens opacities were found, but Thomson, who was a dermatologist, in a later report did not mention cataracts.  The lens opacities are usually nuclear or posterior cortical in location and may be evident in 50% of patients.  Iris stromal changes such as hypoplasia have also been reported.  Eyelashes and/or eyebrows may be sparse.  This is likely the same disorder as the previously described ‘mesodermal dysgenesis of the iris and skeletal dysplasia’ and formerly listed as 270240 in OMIM.

Systemic Features: 

This is a clinically heterogeneous disorder.  Skin atrophy with pigmentary changes, telangiectasia, short stature, premature aging, and skeletal abnormalities are characteristic.  There is an increased risk of malignancy, particularly osteosarcomas and skin cancer.  Saddle nose, sparse hair, hypogonadism, dysplastic nails, and teeth anomalies have also been described.

The skin is usually normal at birth but an erythematous rash typically appears in the first six months of life accompanied by swelling and blistering.  Eventually areas of hypo- and hyperpigmentation appear in a reticulated pattern with spots of punctate atrophy and telangiectasia.  Hyperkeratosis of the soles of the feet is common.  The skeletal abnormalities of dysplasia, radial ray defects, and missing bones are often evident at birth while osteopenia and delayed bone maturation are evident later.

Genetics

This is an autosomal recessive disorder in which most patients have mutations in the RECQL4 gene (8q24.3).

Mutations in the same gene cause Baller-Gerold syndrome (218600) suggesting that the two disorders are allelic but the phenotypes are considerably different.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no treatment for the primary disorder but patients must be monitored for malignancies.  Visually significant cataracts should be removed.  It has been recommended that patients avoid excessive sun exposure to reduce the risk of skin cancers.

References
Article Title: 

Galactose Epimerase Deficiency

Clinical Characteristics
Ocular Features: 

At least some patients have childhood cataracts which may be unilateral.  Direct assay of GALE activity in lenses shows a significant decrease in at least some patients.

Systemic Features: 

This rare disorder of galactose metabolism has an especially wide range of expression.  Some patients seem to have little or no clinical disease whereas others are severely affected.   Early cases were found to have epimerase deficiency only in circulating red blood cells while other cells seemed to have normal levels of the enzyme.  Some of these patients have virtually no symptoms.  Later, cases were found that resembled classic galactosemia (230400) in presentation and even responded to galactose restriction diets. Current thought favors the hypothesis that the same gene defect is responsible for the entire continuum of clinical disease.  Red blood cells have elevated levels of galactose-1-phosphate.

 

Genetics

This is an autosomal recessive disorder resulting from mutations in the GALE gene (1p36-p35.

Another disorder of galactose metabolism causing early onset cataracts is galactokinase deficiency (230200) caused by mutations in GALK1.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

A galactose-restricted diet is beneficial.  Since these patients are unable to utilize the endogenous pathway of synthesis for UDP-galactose they are dependent on exogenous galactose and therefore some galactose is required in the diet.

References
Article Title: 

Galactosemia

Clinical Characteristics
Ocular Features: 

Neonatal cataracts are found among at least 30% of infants with this disorder.  However, early (before 17 days of age) dietary restrictions can prevent their formation or even lead to regression.  They result from the osmotic imbalance caused by the presence of accumulated galactitol.  Neonates may suffer vitreous hemorrhages from the coagulopathy but this is rare.

Systemic Features: 

In spite of early and adequate treatment, however, many adults have residual problems.  Cataracts have been found in 21%, decreased bone density in 24%, tremor in 46%, ataxia in 15%, and dysarthria in 24%.  Few patients of either sex have children and all females have premature ovarian insufficiency.  Depression and anxiety are present in 39-67%.  It has been estimated that there is a twofold increase in the odds of depression with each 10 year increment of age.

Genetics

This is an autosomal recessive disorder resulting from mutations in the GALT gene (9p13) encoding galactose-1-phosphate uridylyltransferase.

For other disorders of galactose metabolism see galactose epimerase deficiency (230350) and galactokinase deficiency (230200).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Treatment with a lactose- and galactose-free diet within the first 3-17 days can prevent the formation of cataracts.  Few need surgical removal.  Liver function improves and a reduction in icterus can be seen.  It can also prevent fatal E. coli sepsis.  However, long term effects have been disappointing as many patients still develop mental and motor dysfunction as well as speech difficulties (dyspraxia).  The long term outcome seems to depend upon the level of GALT enzyme activity which varies considerably.

Special education and speech therapy may be beneficial.  Depression in older patients should be offered where indicated.

References
Article Title: 

The adult galactosemic phenotype

Waisbren SE, Potter NL, Gordon CM, Green RC, Greenstein P, Gubbels CS, Rubio-Gozalbo E, Schomer D, Welt C, Anastasoaie V, D'Anna K, Gentile J, Guo CY, Hecht L, Jackson R, Jansma BM, Li Y, Lip V, Miller DT, Murray M, Power L, Quinn N, Rohr F, Shen Y, Skinder-Meredith A, Timmers I, Tunick R, Wessel A, Wu BL, Levy H, Elsas L, Berry GT. The adult galactosemic phenotype. J Inherit Metab Dis. 2011 Jul 21. [Epub ahead of print]

PubMed ID: 
21779791

Dermochondrocorneal Dystrophy

Clinical Characteristics
Ocular Features: 

A corneal dystrophy is part of this syndrome.  Patients develop confluent, drop-like subepithelial whitish-brown infiltrates of the central cornea with some anterior stromal involvement together with stellate anterior cortical cataracts.  The intervening stroma appears hazy.  The epithelial surface remains intact but may be irregular over the superficial stromal infiltrates. The corneal opacities follow the skin and hand deformities and may be accompanied by a vascularized pannus.  Diagnosis can usually be made in the first decade of life.  Visual acuity in young adults may be reduced to the 20/80 - 20/100 range.

Systemic Features: 

Xanthomatous nodules are primarily located on the pinnae, hands, elbows, and nose.  Most of the nodules are small and primarily of cosmetic significance.  They have also been reported in oral mucosa and gingival tissue.  Hyperplasia of the oral mucosa is common.  Deformities of the hands and feet are also seen.

Genetics

Both autosomal dominant and autosomal recessive modes of inheritance have been proposed but insufficient numbers of families have been reported to be conclusive.

Treatment
Treatment Options: 

Corneal grafts could be visually beneficial but the vascularized pannus increases the risk of rejection.  CO2 laser treatment can reduce the cutaneous chondromes.  Gingival lesions and hyperplasia of the oral mucosa may require surgical treatment.

References
Article Title: 

Chondrodysplasia Punctata 2

Clinical Characteristics
Ocular Features: 

Early onset cataracts, often sectorial, are the major ocular feature of this syndrome.  Micropthalmia and microcornea have been observed.  There may be local vitreoretinal abnormalities leading to localized detachments and retinoschisis.

Systemic Features: 

The cartilage disease in this disorder leads to short stature that is often asymmetrical.  There is considerable variation in skeletal manifestations as the spine as well as the limbs can be involved.  The skin at birth may be scaly and erythrodermic.  Later the skin pigmentation may assume a whorled pattern and hyperkeratosis appears, often in a segmental pattern consistent with X-chromosomal mosaicism.  The skin may also be ichthyotic.  The nasal bridge is often flat with frontal bossing.  Flexion contractures are sometimes seen.  Cicatricial alopecia and coarse hair are often noted in adults.

Genetics

A number of skeletal disorders are classified as chondrodysplasia punctata, and there is considerable clinical and genetic heterogeneity (see also rhizomelic chondrodysplasia punctata [215100] in this database for an autosomal recessive form) which has yet to be worked out.  The disorder described here is an X-linked dominant disorder with lethality in males.  It results from a mutation in the EBP gene (Xp11.23-p11.22) causing difficulty in converting lanosterol to cholesterol.  The diagnosis can be confirmed by finding increased plasma accumulation of precursors of sterols 8(9)-cholestenol and 8-dehydrocholesterol. Rare severely affected males with hypotonia, seizures, cerebellar atrophy, agenesis of the corpus callosum, and developmental delays have been reported. 

The X-linked recessive (CDPX1;302950), autosomal dominant tibia-metacarpal (118651), and humero-metacarpal types are not associated with cataracts.

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

Cataract extraction may improve vision.  Sun protection is advised.

References
Article Title: 

Incontinentia Pigmenti

Clinical Characteristics
Ocular Features: 

This is primarily a disorder of skin, teeth, hair, and the central nervous system but 35% of patients have important ocular features.  The iris is variably atrophic and has pigmentary anomalies often with posterior synechiae.  Nystagmus, strabismus, and limited vision are often present.  The majority (up to 90%) of individuals have significant retinal disease.  The retinal vascular pattern is anomalous with tortuosity in some areas and absence of vessels in others.  Preretinal fibrosis and retinal detachments may suggest the presence of a retinoblastoma.  Cataracts are common in patients who have a retinal detachment and some patients have microphthalmia. The retinal pigment epithelium is often abnormal with various-sized patches of sharply demarcated depigmentation.  Cases with uveitis, papillitis and chorioretinitis have been observed and it has been suggested that the observed retinal and choroidal changes result from prior inflammatory disease, perhaps even occurring in utero. There is a great deal of asymmetry in the clinical findings in the two eyes.

Systemic Features: 

Skin changes consisting of erythematous eruptions in a linear pattern are often present at birth and this may be followed by a verrucous stage.  The acute, early findings of inflammatory disease eventually subside, ultimately resulting in pigmentary changes that appear in a 'marbled pattern' in young adults.  Hypodontia and anodontia may be present.  Alopecia and CNS abnormalities are found in nearly half of patients.  Skeletal and structural deformities are common in patients with severe neurological deficits.  The only sign of this disorder in adult women may be a whorled pattern of scarring alopecia.

As many as 30% of patients have neurological features which may be present in the neonatal period.  Seizures of various types occur in 30% of patients.  MRI findings include periventricular and subcortical white matter changes, as well as corpus callosum hypoplasia, cerebral atrophy, and cerebellar hypoplasia.

 

Genetics

The majority of evidence suggests that this is an X-linked dominant disorder with lethality in males although sporadic cases occur.  The mutation occurs as a genomic rearrangement of the IKK-gamma gene, also known as NEMO (IKBKG) located at Xq28.  There is evidence from skin cultures that cells with the mutant X chromosome inactivated are preferentially viable.  It has been proposed that cells with the mutant bearing X chromosome as the active one are gradually replaced by those in which the normal X chromosome is active accounting for the post-natal course of the skin disease.

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

No treatment for the generalized disorder is available although ocular surgery might be beneficial in rare cases with cataracts and detachments.

References
Article Title: 

Cerebrotendinous Xanthomatosis

Clinical Characteristics
Ocular Features: 

Juvenile cataracts are the primary ocular feature of this disorder and are found in virtually all patients.  These often cause the first symptoms and become evident in the first decade and almost always by the third decade of life.  Lens opacification may require extraction at that time and aspirated lens material may contain lipid-containing vacuoles.  However, some cataracts may not be diagnosed until the 5th or 6th decades after the onset of neurological symptoms, usually because the opacities are located in the peripheral cortex and do not cause visual symptoms. 

Optic atrophy occurs in nearly half of affected individuals.  Yellowish flakes resembling cholesterol crystals can sometimes be seen in the vitreous. The fundus may have scattered hard exudates and cholesterol-like deposits along the vascular arcades and arterioles show evidence of atherosclerosis.  RPE window defects are common.

Systemic Features: 

CTX has serious systemic neurologic signs and symptoms resulting from a deficiency of a mitochondrial enzyme, sterol 27-hydroxylase.  The result is reduced bile acid synthesis and increased levels of cholestanol in plasma, tissues, and CSF.  This results in a characteristic phenotype of tendon xanthomas, and neurological dysfunction including mental regression or illness, cerebellar ataxia, peripheral neuropathy, seizures, and pyramidal signs to various degrees.  Neonatal jaundice and diarrhea are common.

Genetics

This autosomal recessive disorder results from a mutation in the CYP27A1 gene (2q33-qter) encoding sterol 27-hydroxylase.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

This is a treatable disorder in which administration of chenodeoxycholic acid (CDCA) is beneficial.  This compound is virtually absent from bile in people with CTX.  Exogenous administration reduces high levels of cholesterol and cholestanol in the CSF, tissues, and plasma with improvement in mental function and signs of peripheral neuropathy and cerebellar dysfunction.  It is frequently given in combination with other HMG-CoA inhibitors such as pravastatin.  Early diagnosis and treatment are important.

References
Article Title: 

Marshall Syndrome

Clinical Characteristics
Ocular Features: 

Myopia is a common feature.  The globes appear prominent with evident hypertelorism, perhaps in part due to shallow orbits.  The vitreous is abnormally fluid.  The beaded vitreous pattern seen in Stickler syndrome type II (604841), with which Marshall syndrome is sometimes confused, is not seen in Marshall syndrome, nor is the same frequency of retinal detachments.  Congenital or juvenile cataracts were present in Marshall’s original family.

Systemic Features: 

The midface is flat with some features of the Pierre-Robin phenotype.  The nasal root is flat and the nares anteverted.  Patients tend to be short in stature and joints are often stiff.  Small iliac wings and a thickened calvarium can be seen radiologically together with other bone deformities.  Abnormal frontal sinuses and intracranial calcifications have also been reported.  Sensorineural hearing loss may be noted during the first year of life with age-related progression.  Osteoarthritis of the knees and lumbosacral spine begins in the 4th and 5th decades.  Features of anhidrotic ectodermal dysplasia such as hypohidrosis and hypotrichosis are present in some patients.  Individuals may have linear areas of hyperpigmentation on the trunk and limbs.

Genetics

The syndromal status of Marshall syndrome as a unique entity remains uncertain inasmuch as there are many overlapping clinical features with Stickler syndrome type II (604841) and both result from mutations in the COL11A1 gene (1p21).  Autosomal dominant inheritance is common to both although autosomal recessive inheritance has been proposed for a few families with presumed Marshall syndrome. Stickler syndrome type II (604841) and Marshall syndrome may be allelic or even the same disorder.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for this disorder beyond cataract removal.  Patients need to be monitored for retinal breaks and detachments.

References
Article Title: 

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