FREM2

Fraser Syndrome 2

Clinical Characteristics
Ocular Features: 

Cryptophthalmos, both unilateral and bilateral, is the ocular hallmark.  The lid margins may be fused.

Systemic Features: 

Multiple systemic malformations are usually present.  A small mouth, nasal dysplasia with hypoplastic alae nasi, and syndactyly may be seen.  Urogenital malformations such as renal dysgenesis or dysplasia, ambiguous genitalia, streak ovaries may be present.  Pulmonary hypoplasia and imperforate anus have been reported.

Genetics

Homozygous mutations in the FREM2 gene (13q13.3) have been identified in Fraser syndrome 2.  

See Fraser syndrome 1 (219000) for additional features that may be present in Fraser syndrome.

Fraser syndrome 3 (617667) results from homozygous mutations in GRIP1.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Cryptophthalmos

Clinical Characteristics
Ocular Features: 

It may be that ankyloblepharon occurs in the absence of other abnormalities but in most cases the globes are small and malformed as well.  The combination of upper and lower lid fusion associated with microophthalmia effectively precludes visualization of the globes in many cases, hence the term cryptophthalmos. Lid colobomas may be present in patients with incomplete fusion of the lid margins.  There are often adhesions between the lids and cornea while the anterior chamber may have features of Peters anomaly.  Posterior chamber abnormalities such as optic nerve hypoplasia and retinal dysplasia with other tissues such as bone may also be present.  Rarely patients may respond to bright lights.  The condition may be unilateral or bilateral. The lacrimal drainage system may be malformed or absent while the eyebrows are often missing as well.  In severe cases, the forehead skin appears to be continuous with that of the cheeks.

Cryptophthalmos is also feature of other malformation syndromes most notably that described by Fraser (219000).

Systemic Features: 

The type of cryptophthalmos described here is sometimes called simple or isolated since no systemic malformations are associated.  It should be noted, however, that other ocular abnormalities are almost always associated and the clinical features of the hidden eye are anything but isolated or simple.

Genetics

A small number of families with a vertical pattern of inheritance suggest that at least some cases are inherited in an autosomal dominant pattern but no locus has been identified.  This pattern distinguishes such cases from those with the Fraser cryptophthalmos syndrome (219000) which has an autosomal recessive pattern of inheritance.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Attempts have been made to surgically create a lid fissure but the lack of conjunctival cul de sacs and fusion of the lids to the cornea in many cases can lead to irreparable complications.

References
Article Title: 

Isolated and syndromic cryptophthalmos

Thomas IT, Frias JL, Felix V, Sanchez de Leon L, Hernandez RA, Jones MC. Isolated and syndromic cryptophthalmos. Am J Med Genet. 1986 Sep;25(1):85-98. Review.

PubMed ID: 
3099574
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