microphthalmia

Coloboma, Isolated

Clinical Characteristics
Ocular Features: 

Colobomas of the uveal tract are often found in association with other ocular anomalies including those with systemic disease. They are usually located in the inferonasal quadrant as a result of defective closure of the embryonic fissure in the optic cup.  Most involve the nearly complete iris and resemble a keyhole but they may also be partial resulting in an oval pupil.  They are sometimes unilateral in which case the involved iris may be more heavily pigmented than the contralateral one.  They may involve only the iris (simple coloboma) but often are more extensive with involvement of the ciliary body, retina, lens, choroid, and even the optic nerve.  They are frequently associated with microphthalmia (or microphthalmia with cyst [5.6%]) and microcornea (79%). 

Systemic Features: 

None by definition.

Genetics

Isolated colobomas are clinically and genetically heterogeneous resulting from mutations in SHH (7q36.3), PAX6 (11p13), and ABCB6 (2q35) among others.  Large pedigrees with typical autosomal dominant transmission patterns have been reported.

Homozygous mutations in SALL2 (14q11.1-q12.1) have also been reported in patients with isolated colobomas.  Studies of sall2-deficient mice show defects in closure of the anterior optic fissure while posterior closure proceeds normally.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Simple iris colobomas usually do not require treatment.  The visual prognosis depends upon the structures involved.  Those with microcornea usually have a lower acuity and, of course, eyes with the most extensive involvement of the uveal tract and/or the optic nerve may have the least vision. Low vision aids can be helpful in selected individuals.

References
Article Title: 

Mutation of SALL2 causes recessive ocular coloboma in humans and mice

Kelberman D, Islam L, Lakowski J, Bacchelli C, Chanudet E, Lescai F, Patel A, Stupka E, Buck A, Wolf S, Beales PL, Jacques TS, Bitner-Glindzicz M, Liasis A, Lehmann OJ, Kohlhase J, Nischal KK, Sowden JC. Mutation of SALL2 causes recessive ocular coloboma in humans and mice. Hum Mol Genet. 2014 Jan 12. [Epub ahead of print].

PubMed ID: 
24412933

ABCB6 Mutations Cause Ocular Coloboma

Wang L, He F, Bu J, Liu X, Du W, Dong J, Cooney JD, Dubey SK, Shi Y, Gong B, Li J, McBride PF, Jia Y, Lu F, Soltis KA, Lin Y, Namburi P, Liang C, Sundaresan P, Paw BH, Li DY, Phillips JD, Yang Z. ABCB6 Mutations Cause Ocular Coloboma. Am J Hum Genet. 2012 Jan 13;90(1):40-8.

PubMed ID: 
22226084

Branchiooculofacial Syndrome

Clinical Characteristics
Ocular Features: 

Microphthalmos, or anophthalmia, and an imperforate nasolacrimal duct are the primary ocular features in this syndrome.  The nasolacrimal ducts may open onto the skin adjacent to the lacrimal sac.  Uveal tract and optic nerve colobomas are present in nearly half of patients. Strabismus is sometimes seen.  Cataracts are present in about 25% of patients as well.  The lid fissures are often slanted upwards.

Systemic Features: 

A cleft lip and/or palate are common features.  There may be preauricular pits, lip pits, a highly arched palate, and hypodontia.  Some individuals have subcutaneous cysts in the scalp.  Postauricular cervical branchial and supraauricular defects are often present as well.  It is not unusual to see some skin discoloration behind the ears.  The nasal bridge is broad, the top of the nose is flattened, and the philtrum is often short.  The ears are often enlarged or malformed and in 70% of patients there is some hearing loss which is usually conductive in origin but neurosensory deafness has also been documented.  Premature graying of hair is common.  Kidney malformations and dysfunction have been documented.  Mental function is usually normal.  Preaxial polydactyly is an uncommon feature.

Genetics

This is an autosomal dominant disorder resulting from mutations in the TFAP2A gene (6p34.3).  Both deletions and insertions have been identified.  However, 50-60% of patients have de novo mutations.  As in many autosomal dominant disorders there is considerable clinical heterogeneity and few patients have all of the signs.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Treatment requires a multidisciplinary approach with oculoplastic, ophthalmic, and ENT surgeons.  Physical, speech, hearing, and learning specialists can be helpful.

References
Article Title: 

Further delineation of the branchio-oculo-facial syndrome

Lin AE, Gorlin RJ, Lurie IW, Brunner HG, van der Burgt I, Naumchik IV, Rumyantseva NV, Stengel-Rutkowski S, Rosenbaum K, Meinecke P, et al. Further delineation of the branchio-oculo-facial syndrome. Am J Med Genet. 1995 Mar 13;56(1):42-59. Review.

PubMed ID: 
7747785

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: 

Microphthalmia, Syndromic 3

Clinical Characteristics
Ocular Features: 

Microphthalmia or clinical anophthalmia is the major ocular malformation in this disorder but optic nerve hypoplasia or even aplasia may also be present.  Colobomas and congenital cataracts may be seen.

Systemic Features: 

Esophageal atresia and sometimes tracheoesophageal fistula sometimes coexist. The ears can be low-set and malformed and sensorineural hearing loss is often present.  Facial palsy has been reported.  The penis may be small and combined with cryptorchidism while physical growth retardation is common.  Other less common malformations include cleft palate, vertebral anomalies, cardiac anomalies, body asymmetry, and microcephaly.  A few patients have had radiologically evident CNS malformations such as dilated ventricles, hippocampal hypoplasia, abnormal white matter, and holoprosencephaly.  However, intellectual development and function have been normal in other patients.

Genetics

This is an autosomal dominant disorder secondary to heterozygous mutations in the SOX2 gene (3q26.33).  Chromosomal aberrations involving this region of chromosome 3 have also been found.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Depending upon the severity of malformations, life expectancy can be normal but some patients have died in the neonatal period.  Certain defects such as those of the heart, palate and esophagus can be surgically repaired.  Hearing device can be helpful but no treatment is available for the eyeball malformations.

References
Article Title: 

Microphthalmia, Syndromic 2

Clinical Characteristics
Ocular Features: 

Microphthalmia with congenital cataracts are the outstanding ocular features of this syndrome.  Some patients have glaucoma.  Blepharophimosis, ptosis, and ankyloblepharon have also been reported.

Systemic Features: 

Facial dysmorphism, dental anomalies and cardiac defects are consistently present.  The face may appear elongated while the nose can be short with a broad tip and long philtrum.  The primary teeth often persist into the second decade but oligodontia, hyperdontia, and dental radiculomegaly may be seen as well.  Reported cardiac defects include ASD, VSD and floppy valves.  Some patients have cleft palate.  Renal, and intestinal malformations have also been described and some patients exhibit psychomotor delays.

Genetics

This is an X-linked disorder secondary to a mutation in the BCOR gene at Xp11.4.  Because virtually all patients are female, it has been suggested that this is an X-linked dominant mutation with lethality in hemizygous males (mother-daughter transmission has been reported).  This is one of several disorders [others being Incontinentia pigmenti (308300)and focal dermal hypoplasia (305600)] in which skewed X-chromosome inactivation has been demonstrated.

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

Cataracts can be removed and glaucoma requires treatment.

References
Article Title: 

Microphthalmia, Syndromic 8

Clinical Characteristics
Ocular Features: 

Microphthalmia is a consistent feature and short palpebral fissures have been described in one patient.  Microcornea has also been noted.  At least one patient was blind.

Systemic Features: 

The skull is small and mental retardation is usually a feature.  Other variable abnormalities include cardiac defects, prognathism, split-feet, cryptorchidism, and cleft lip and palate.  Few patients have been reported and the full phenotype is unknown.

Genetics

The gene remains unidentified in this rare syndrome but a locus has been identified at 6p21.  In at least one patient with a balanced translocation of t(6;13)(q21;q12) a disruption in the SNX3 gene at 6q21 was identified.  Most cases occur sporadically and have cytogenetic abnormalities.

Treatment
Treatment Options: 

No treatment is known.

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

Microphthalmia with Limb Anomalies

Clinical Characteristics
Ocular Features: 

Patients have either microphthalmia or anophthalmia which may be present unilaterally or bilaterally.  The MRI in several patients has revealed complete absence of the globes, optic nerves, chiasm, and optic tracts.  The eyelashes are often sparse with shortened palpebral fissures and broad lateral eyebrows.

Systemic Features: 

Global developmental delays, failure to thrive, and mild to moderate mental retardation are common.   Syndactyly, polydactyly, and oligodactyly with hypoplasia of the long bones are present to a variable degree.  Synostosis in the digits, ankles, and wrist is often seen.  A split hand (lobster-claw deformity) is variably present.  Other anomalies such as the kidneys (horseshoe kidney), undescended testes, anomalous venous circulation and deformed vertebrae have been reported.  The midface is often flattened.  A high palate, cleft lip, and mild scoliosis may be seen.

Genetics

This is an autosomal recessive disorder resulting from homozygous mutations in the SMOC1 gene (14q24.2) but there is some evidence of genetic heterogeneity as the disorder has been mapped to 10p11.23 in several families.  However, no causative mutations were found in this region.  Consanguinity among parents is common.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no treatment in most cases for the ocular malformations.  Some of the limb anomalies may be surgically correctable.

References
Article Title: 

SMOC1 is essential for ocular and limb development in humans and mice

Okada I, Hamanoue H, Terada K, Tohma T, Megarbane A, Chouery E, Abou-Ghoch J, Jalkh N, Cogulu O, Ozkinay F, Horie K, Takeda J, Furuichi T, Ikegawa S, Nishiyama K, Miyatake S, Nishimura A, Mizuguchi T, Niikawa N, Hirahara F, Kaname T, Yoshiura K, Tsurusaki Y, Doi H, Miyake N, Furukawa T, Matsumoto N, Saitsu H. SMOC1 is essential for ocular and limb development in humans and mice. Am J Hum Genet. 2011 Jan 7;88(1):30-41.

PubMed ID: 
21194678

A locus for ophthalmo-acromelic syndrome mapped to 10p11.23

Hamanoue H, Megarbane A, Tohma T, Nishimura A, Mizuguchi T, Saitsu H, Sakai H, Miura S, Toda T, Miyake N, Niikawa N, Yoshiura K, Hirahara F, Matsumoto N. A locus for ophthalmo-acromelic syndrome mapped to 10p11.23. Am J Med Genet A. 2009 Mar;149A(3):336-42.

PubMed ID: 
19208380

Aphakia, Congenital Primary

Clinical Characteristics
Ocular Features: 

There is complete absence of the lens and with it aplasia of the anterior segment including complete absence of the iris, ciliary body, and trabecular meshwork.  In an autopsied case, the cornea was thinned and lacked endothelium, Bowman layer, and Descemet membrane while the retina was dysplastic.  In the single family reported, 2 sibs had sclerocornea and one had megalocornea.  Normal pressure was reported in several eyes but a single eye in one patient at the age of 3 years developed buphthalmos with elevated pressure.

Systemic Features: 

No systemic abnormalities have been reported.

Genetics

Homozygosity of a nonsense mutation in the FOXE3 transcription factor gene (1p32) seems to be responsible for this autosomal recessive disorder.  The same gene has been implicated in rare cases of Peters anomaly (604229) and in anterior segment mesenchymal dysgenesis (107250).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is known to restore vision.

References
Article Title: 

Microphthalmia, Syndromic 9

Clinical Characteristics
Ocular Features: 

Both microphthalmia and clinical anophthalmia have been described in this syndrome.  However, autopsy has shown true anophthalmia in a few cases who were stillborn or died in the neonatal period.  At least one eye can be cystic. The optic nerves are often hypoplastic and may be absent.  High, upward-arching eyebrows may be seen.

Systemic Features: 

An early manifestation of this disorder is neonatal pulmonary distress.  The lungs are usually hypoplastic or malformed. Cardiac malformations such as patent ductus arteriosus, septal and valvular defects, tetralogy of Fallot, and single ventricles are often present.  Diaphragmatic hernias or defects are common but hiatal hernias and frank eventration of abdominal contents have also been reported.  Renal anomalies and intrauterine growth retardation have been noted.         

Some infants have micrognathia, low-set ears, a broad nasal bridge, brachycephaly, and midline clefts of the palate.  Cerebral malformations are seldom present.

Genetics

Homozygous mutations in the STRA6 gene (15q24.1) have been found in a few cases which suggests autosomal recessive inheritance.  Parental consanguinity has been reported in some families.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Treatment is directed at the repair of the organ defects in selected cases that have survival potential.   Survival rates are poor but those less severely affected may live for a decade.

References
Article Title: 

The PDAC syndrome (pulmonary hypoplasia/agenesis, diaphragmatic hernia/eventration, anophthalmia/microphthalmia, and cardiac defect) (Spear syndrome, Matthew-Wood syndrome): report of eight cases including a living child and further evidence for autosomal

Chitayat D, Sroka H, Keating S, Colby RS, Ryan G, Toi A, Blaser S, Viero S, Devisme L, Boute-B?(c)n?(c)jean O, Manouvrier-Hanu S, Mortier G, Loeys B, Rauch A, Bitoun P. The PDAC syndrome (pulmonary hypoplasia/agenesis, diaphragmatic hernia/eventration, anophthalmia/microphthalmia, and cardiac defect) (Spear syndrome, Matthew-Wood syndrome): report of eight cases including a living child and further evidence for autosomal recessive inheritance. Am J Med Genet A. 2007 Jun 15;143A(12):1268-81.

PubMed ID: 
17506106

Mutations in STRA6 cause a broad spectrum of malformations including anophthalmia, congenital heart defects, diaphragmatic hernia, alveolar capillary dysplasia, lung hypoplasia, and mental retardation

Pasutto F, Sticht H, Hammersen G, Gillessen-Kaesbach G, Fitzpatrick DR, N?ornberg G, Brasch F, Schirmer-Zimmermann H, Tolmie JL, Chitayat D, Houge G, Fern?degndez-Mart??nez L, Keating S, Mortier G, Hennekam RC, von der Wense A, Slavotinek A, Meinecke P, Bitoun P, Becker C, N?ornberg P, Reis A, Rauch A. Mutations in STRA6 cause a broad spectrum of malformations including anophthalmia, congenital heart defects, diaphragmatic hernia, alveolar capillary dysplasia, lung hypoplasia, and mental retardation. Am J Hum Genet. 2007 Mar;80(3):550-60.

PubMed ID: 
17273977

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