cataract

Neu-Laxova Syndrome 1

Clinical Characteristics
Ocular Features: 

The globes are prominent, an appearance that is exaggerated sometimes by absence of the eyelids or ectropion.  The lashes may be absent in other patients.  Cloudy corneas and cataracts have been described.

Systemic Features: 

This is a lethal dysplasia-malformation syndrome in which some infants are stillborn while others do not live beyond a few days.  The placenta is often small and the umbilical cord is short.  Decreased fetal movements and polyhydramnios are often noted.  Microcephaly can be striking at birth but there is overall intrauterine growth retardation.  The skin is ichthyotic and dysplastic containing excess fatty tissue beneath the epidermis.  Digits are often small and may be fused (syndactyly).  There is generalized edema with ‘puffiness’ of the hands and feet.  The lungs are frequently underdeveloped and cardiac defects such as septal openings, patent ductus arteriosus and transposition of great vessels are common.  Males often have cryptorchidism while females have a bifid uterus and renal dysgenesis has been reported.

The face is dysmorphic with prominent globes (in spite of microphthalmia), the ears are large and malformed, the forehead is sloping, the nose is flattened and the jaw is small.  Some infants have a cleft lip and palate while the mouth is round and gaping.  The neck is usually short.

Severe brain malformations such as lissencephaly, cerebellar hypoplasia, and dysgenesis/agenesis of the corpus callosum are frequently present.

Genetics

This is an autosomal recessive disorder secondary to mutations in the PHGDH gene (1p12).

This condition has some clinical overlap with Neu-Laxova syndrome 2 (616038) but the latter is less severe and is caused by a different mutation.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available.

References
Article Title: 

Neu-laxova syndrome is a heterogeneous metabolic disorder caused by defects in enzymes of the L-serine biosynthesis pathway

Acuna-Hidalgo R, Schanze D, Kariminejad A, Nordgren A, Kariminejad MH, Conner P, Grigelioniene G, Nilsson D, Nordenskjold M, Wedell A, Freyer C, Wredenberg A, Wieczorek D, Gillessen-Kaesbach G, Kayserili H, Elcioglu N, Ghaderi-Sohi S, Goodarzi P, Setayesh H, van de Vorst M, Steehouwer M, Pfundt R, Krabichler B, Curry C, MacKenzie MG, Boycott KM, Gilissen C, Janecke AR, Hoischen A, Zenker M. Neu-laxova syndrome is a heterogeneous metabolic disorder caused by defects in enzymes of the L-serine biosynthesis pathway. Am J Hum Genet. 2014 Sep 4;95(3):285-93.

PubMed ID: 
25152457

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: 

Persistent Hyperplastic Primary Vitreous

Clinical Characteristics
Ocular Features: 

Persistence and hyperplasia of the embryonic vitreous in most individuals results in significant ocular morbidity.  It results from a transcription factor deficiency in retinal ganglion cells which in turn negatively impacts development of the retinal vasculature.  As a consequence, the fetal hyaloid vasculature fails to regress and its persistence leads to a retrolental mass.

PHPV usually occurs unilaterally and affected eyes are generally blind from birth. Leukocoria secondary to the presence of a retrolental fibrovascular stalk is easily visible.  Nystagmus is frequently present and some patients have microphthalmos. The anterior segment may also be involved as evidenced by the presence of peripheral anterior synechiae, corneal opacities, cataracts, and glaucoma.  Contracture of the retrolental tissue In the posterior chamber results in the ciliary processes being pulled centrally and can lead to hemorrhage and retinal detachment. 

The clinical manifestations can make it difficult to distinguish from Norrie disease.

Systemic Features: 

No consistent systemic signs have been reported in PHPV individuals.

Genetics

The majority of PHPV cases occur sporadically, but families with transmission patterns compatible with both autosomal recessive and autosomal dominant patterns have been reported.

A six-generation family has been reported in which affected members had homozygous mutations in ATOH7 (10q21.3).  Based on mouse studies, this gene is expressed in the developing optic cup at the time that coincides with retinal ganglion cell formation.  Mice with absence of functioning Atoh7 lack retinal ganglion cells and optic nerves and develop PHPV.

A single family with presumed bilateral PHPV in 3 generations in a pattern consistent with autosomal dominant inheritance has been reported (611308).  However, no genotyping was reported and only the proband and his father had ophthalmologic examinations.

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

No medical or surgical treatment is effective.  The majority of individuals have no light perception.

References
Article Title: 

Mowat-Wilson Syndrome

Clinical Characteristics
Ocular Features: 

Most reports of Mowat-Wilson disorders provide only incomplete ocular findings and the full phenotype remains to be described.  Most of the reported findings are part of the facial phenotype, such as downward slanting palpebral fissures, and ‘wedge-shaped’ eyebrows with the medial portion visibly wider than the temporal region.  Hypertelorism, strabismus and telecanthus have also been noted.  However, optic nerve atrophyor aplasia, RPE atrophy, microphthalmia, ptosis, and cataracts are sometimes present while strabismus is more common.  Iris and other uveal colobomas may be present and at least one patient has been reported with retinal aplasia.  There may be considerable asymmetry in the features among the two eyes.

Systemic Features: 

This is a highly complex dysmorphic developmental disorder with unusual progression of facial features.  Birth weight and length are usually normal but later there is general somatic and mental growth delay with microcephaly (pre- and post natal), short stature, intellectual disability, and epilepsy (70%).  Hypotonia has been noted at birth.  A significant proportion (~50%) of patients have Hirschsprung disease with megacolon.  Congenital heart defects are common, many involving septal openings.  Hypospadias is often present with or without other genitourinary anomalies.  Teeth are often crowded and crooked.  The earlobes may be flattened and may have a central depression.

The facial features are present in early childhood but as they mature the upper half of the nasal profile becomes convex, while the nasal tip becomes longer and overhangs the philtrum.  The eyes appear more deeply set.  The chin lengthens and prognathism becomes apparent.  IQ levels cannot be determined but many individuals exhibit behavioral or emotional disturbances.

Genetics

Heterozygous mutations in ZEB2 (2q22.3) are responsible for most cases (81%) of this disorder.  A large number of molecular mutations, many of the nonsense type, have been reported. About 2-4% of patients have cytogenetic alterations involving the 2q22 region.

Another disorder with microcephaly, intellectual disability and Hirschsprung disease is Goldberg-Shprintzen syndrome (609460) with mutations in the KIAA1279 gene.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Treatment may be directed at specific defects but there is no treatment for the general disorder. Individuals can live to adulthood. Treatment is largely symptomatic.  Physical and speech treatment can be helpful if initiated early.

References
Article Title: 

Clinical spectrum of eye malformations in four patients with Mowat-Wilson syndrome

Bourchany A, Giurgea I, Thevenon J, Goldenberg A, Morin G, Bremond-Gignac D, Paillot C, Lafontaine PO, Thouvenin D, Massy J, Duncombe A, Thauvin-Robinet C, Masurel-Paulet A, Chehadeh SE, Huet F, Bron A, Creuzot-Garcher C, Lyonnet S, Faivre L. Clinical spectrum of eye malformations in four patients with Mowat-Wilson syndrome. Am J Med Genet A. 2015 Apr 21. [Epub ahead of print]

PubMed ID: 
25899569

The behavioral phenotype of Mowat-Wilson syndrome

Evans E, Einfeld S, Mowat D, Taffe J, Tonge B, Wilson M. The behavioral phenotype of Mowat-Wilson syndrome. Am J Med Genet A. 2012 Feb;158A(2):358-66. doi: 10.1002/ajmg.a.34405.

PubMed ID: 
22246645

Mowat-Wilson syndrome: facial phenotype changing with age: study of 19 Italian patients and review of the literature

Garavelli L, Zollino M, Mainardi PC, Gurrieri F, Rivieri F, Soli F, Verri R, Albertini E, Favaron E, Zignani M, Orteschi D, Bianchi P, Faravelli F, Forzano F, Seri M, Wischmeijer A, Turchetti D, Pompilii E, Gnoli M, Cocchi G, Mazzanti L, Bergamaschi R, De Brasi D, Sperandeo MP, Mari F, Uliana V, Mostardini R, Cecconi M, Grasso M, Sassi S, Sebastio G, Renieri A, Silengo M, Bernasconi S, Wakamatsu N, Neri G. Mowat-Wilson syndrome: facial phenotype changing with age: study of 19 Italian patients and review of the literature. Am J Med Genet A. 2009 Mar;149A(3):417-26. Review.

PubMed ID: 
19215041

Clinical and mutational spectrum of Mowat-Wilson syndrome

Zweier C, Thiel CT, Dufke A, Crow YJ, Meinecke P, Suri M, Ala-Mello S, Beemer F, Bernasconi S, Bianchi P, Bier A, Devriendt K, Dimitrov B, Firth H, Gallagher RC, Garavelli L, Gillessen-Kaesbach G, Hudgins L, K?SS?SSri?SSinen H, Karstens S, Krantz I, Mannhardt A, Medne L, M?ocke J, Kibaek M, Krogh LN, Peippo M, Rittinger O, Schulz S, Schelley SL, Temple IK, Dennis NR, Van der Knaap MS, Wheeler P, Yerushalmi B, Zenker M, Seidel H, Lachmeijer A, Prescott T, Kraus C, Lowry RB, Rauch A. Clinical and mutational spectrum of Mowat-Wilson syndrome. Eur J Med Genet. 2005 Apr-Jun;48(2):97-111

PubMed ID: 
16053902

Microphthalmia, AR

Clinical Characteristics
Ocular Features: 

The most consistent feature associated with mutations in the VSX2 gene is, of course, microphthalmia/anophthalmia.  Other anomalies include dysplasia of the retina, cataracts and/or dislocated lenses, and iris anomalies ranging from hypoplasia to colobomas and absence of the pupils. Colobomas may also involve the posterior uveal tract as well as the optic nerve. The majority of patients are blind.   

Systemic Features: 

No systemic features are associated.

Genetics

This is an autosomal recessive disorder resulting from mutations in the VSX2 (formerly CHX10) gene located at 14q24.3.  The gene is expressed in progenitor cells of the developing neuroretina and in inner nuclear cells of the adult retina.   Most parents are consanguineous.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

None other than rehabilitation.

References
Article Title: 

Hyperferritinemia-Cataract Syndrome

Clinical Characteristics
Ocular Features: 

Lens opacification is the only ocular sign of this disorder.  These may be congenital and nuclear in location but this is variable.  Pulverulent and ‘sunflower’ light-diffracting opacities have also been described and are likely responsible for the glare that many patients experience.  In some patients cataracts may not be diagnosed until adult life.  Ferritin levels in surgically removed lenses are 1,500 times higher than controls and histochemical studies demonstrate that the crystalline lens opacities consist of intracellular L-ferritin.

Systemic Features: 

Serum levels of iron and transferrin saturation are normal but ferritin levels are high.  Most patients are asymptomatic but blood loss may lead to iron deficiency anemia.

Genetics

This is an autosomal dominant disorder resulting from mutations in the FTL gene located at 19q33.33.  Phenotypic variability is common as expressed by serum ferritin levels and the characteristics of the lens opacities.

A patient with homozygosity of the FTL mutation has been reported but the phenotype resembled that of heterozygous patients.

Cataracts may also be present among other disorders of iron metabolism.  For example, mutations in the gene HFE (6p21.3) that is responsible for a form of hemachromotosis (235200), can also be associated with lens opacities consisting of both general nuclear sclerosis and discrete opacities.  Epilepsy may be part of the phenotype as well. 

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No systemic treatment is necessary in most patients but cataracts can be removed if visually significant.

References
Article Title: 

Anterior Segment Mesenchymal Dysgenesis

Clinical Characteristics
Ocular Features: 

The unique status of this entity remains to be established as there are overlapping features with aniridia (106210), and Peters anomaly (604229), posterior embryotoxon, and iridogoniodysgenesis type 1 (601631) and type 2 (137600).  Anterior segment mesenchymal dysgenesis itself is clinically heterogeneous even within families.  Schwalbe line is often anteriorly placed and there may be iris adhesions to the cornea, with or without corneal opacities.  Some patients have microcornea.  All layers of the cornea are dysplastic from the epithelium to the endothelium suggesting abnormal migration or function of neural crest cells.  Lens opacities are highly variable but they can be progressive. Curiously, elevated intraocular pressure is usually not present.  Visual acuity is highly variable with some patients having 20/20 vision and others bare hand motions depending on the degree of opacification of the lens and cornea.

Systemic Features: 

No systemic abnormalities are present.

Genetics

This is an autosomal dominant disorder secondary to mutations in either PITX3 (10q24.32) or FOXE3 (1p32)  which are both transcription factors.  The latter gene is also mutant in congenital primary aphakia (610256) and some cases of Peters anomaly (604229).

See also Anterior Segment Dysgenesis 6 (617315) and Anterior Segment Dysgenesis 8 (617319) for autosomal recessive conditions in which mutations result in malformations of the anterior chamber.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Cataract surgery is indicated in some cases and corneal transplantation has been attempted in a few individuals.

References
Article Title: 

Cataracts, Congenital Zonular Pulverulent 1

Clinical Characteristics
Ocular Features: 

Bilateral lens opacities may be both nuclear and zonular.  The embryonic and fetal nuclei are usually involved and diffuse cortical opacities may also be seen in some patients.  The involved area is therefore larger than the somewhat similar Coppock-like cataract (604307) which is limited to the embryonic nucleus.  The lens opacities may be seen at birth or in early childhood and usually progress. There is considerable clinical variation in the degree and distribution of the usual dust-like opacities which may also be lamellar in distribution with a clear peripheral cortex and minimal nuclear involvement.  Microcornea has also been reported.  In mild cases the lens opacities are primarily clustered along the Y sutures resembling congenital zonular cataracts with sutural opacities (600881).

Three unrelated patients with mutations in GJA8 and total sclerocornea have been reported.  Two of these patients in addition had small abnormal lenses while the third had cataracts and micropthalmia.  Two of the three also develped glaucoma by one year of age.

The nature and morphology of the lens opacities in an adult have been studied by light and scanning electron microscopy.  They are located in the embryonic and fetal nuclei and appear "puffy" with lens fiber irregulaties and entanglement in adjacent areas. 

Systemic Features: 

None.

Genetics

Congenital zonular pulverulent cataracts are inherited in an autosomal dominant pattern resulting from missense mutations in the GJA8 gene (1q21.1) that codes for connexin 50.  These belong to a category of lens opacitites now designated "Cataract 1, Multiple Types" in OMIM (116200). They have been detected in multiple populations and ethnic groups around the world.

Mutations in CZP3 at 13q11-13 coding connexin 46 (601885) result in a similar phenotype (Cataracts, Congenital Zonular Pulverulent 3) suggesting that genetic heterogeneity is present.

This was the first disease locus to be linked on a human autosome, in this case to the Duffy blood group locus on chromosome 1.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Cataract surgery is indicated for visually significant lens opacities which may be required late in the first or early in the second decade of life.

References
Article Title: 

Cataracts, Congenital Sutural with Punctate and Cerulean Opacities

Clinical Characteristics
Ocular Features: 

The anterior and posterior Y sutures have prominent, dense white opacities.  The embryonal and fetal nuclei are clear but the cortex contains gray-bluish, sharply defined and elongated as well as punctate opacities.  These are denser near the posterior pole and the posterior Y suture is also more heavily involved.  The cortical opacities may be arranged in concentric lamellae.  Considerable variation in density of opacities has been noted among patients.

Systemic Features: 

None reported.

Genetics

A large Indian family consisting of 5 generations containing 33 affected individuals has been described.  This is an autosomal dominant disorder in which a mutation has been found in exon 6 of the CRYBB2 gene (22q11.2-q12/22q11.23).  This region contains four crystallin genes as well as the CRYBP1 pseudogene.  It has been suggested that gene conversion between exon 6 of the CRYBB2 gene and CRYBR1 may be responsible for the phenotype.  Three additional families with identical mutations in the same CRYBB2 exon have been reported and, since each family seems to have a unique phenotype, it is likely that more than a simple bp mutation is responsible for the cataracts.  

Some Coppock-like cataracts (604307) also result from mutations in CRYBB2 at the same location but others have  mutations in the CRYGC gene.  Type 2 congenital cerulean cataracts (601547) have also been associated with mutations in the CRYBB2 gene. 

Another autosomal dominant congenital cataract with sutural opacities (600881) has a slightly different phenotype and results from a mutation on chromosome 17.  

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Visually significant cataracts may need to be removed.

References
Article Title: 

Cataracts, Anterior Polar 2

Clinical Characteristics
Ocular Features: 

Lens opacities are located in the central anterior capsule and cortex.  They usually do not interfere significantly with vision.

Systemic Features: 

None.

Genetics

Most cases probably occur sporadically but multigenerational families have been reported in which the transmission pattern is autosomal dominant.  In one family the phenotype was mapped to 17p13 but the gene responsible has not been identified.

Another type (CTAA1) of anterior polar cataract is associated with chromosomal aberrations (115650).

Yet another form of autosomal dominant anterior polar cataract is associated with corneal disease (Cataracts, Anterior Polar with Guttata) (121390).

Other cataracts that map to chromosome 17 are zonular sutural cataract (600881) with a locus at 17q11-q12 and cerulean or ‘blue dot’ cataract (115660) at 17q24.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Lens removal is indicated only if these opacities interfere with vision.

References
Article Title: 

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