corneal rupture

Brittle Cornea Syndrome 2

Clinical Characteristics

Ocular Features

Corneal thinning and extreme fragility are characteristic of BCS2.  Ruptures of the cornea may occur with minimal trauma and repair is often unsatisfactory due to the lack of healthy tissue.  Keratoconus, acute hydrops, keratoglobus, and high myopia are frequently present as well.  Some patients have sclerocornea that obscures the normal limbal landmarks.  The sclera is also thin and the underlying uveal tissue imparts a bluish discoloration to the globe which is especially evident in the area overlying the ciliary body creating what some call a blue halo.

Systemic Features

Skin laxity with easy bruisability, pectus excavatum, scoliosis, congenital hip dislocation, a high arched palate, mitral valve prolapse and recurrent shoulder dislocations are often present.  Hearing impairment with mixed sensorineural/conductive defects is common.

Genetics

This autosomal recessive disorder results from homozygous mutations in PRDM5 (4q27).  Heterozygous carriers may have blue sclerae, small joint hypermobility, and mild thinning of the central cornea. 

BCS2 has many clinical similarities to brittle cornea syndrome 1 (229200) which results from homozygous mutations in ZNF469.

Treatment Options

Treatment for specific defects such as joint dislocations and mitral valve malfunction may be helpful.

References

Burkitt Wright EM, Porter LF, Spencer HL, Clayton-Smith J, Au L, Munier FL, Smithson S, Suri M, Rohrbach M, Manson FD, Black GC. Brittle cornea syndrome: recognition, molecular diagnosis and management. Orphanet J Rare Dis. 2013 May 4;8(1):68. [Epub ahead of print]

PubMed ID: 
23642083

Burkitt Wright EM, Spencer HL, Daly SB, Manson FD, Zeef LA, Urquhart J, Zoppi N, Bonshek R, Tosounidis I, Mohan M, Madden C, Dodds A, Chandler KE, Banka S, Au L, Clayton-Smith J, Khan N, Biesecker LG, Wilson M, Rohrbach M, Colombi M, Giunta C, Black GC. Mutations in PRDM5 in brittle cornea syndrome identify a pathway regulating extracellular matrix development and maintenance. Am J Hum Genet. 2011 Jun 10;88(6):767-77. Erratum in: Am J Hum Genet. 2011 Aug 12;89(2):346.

PubMed ID: 
21664999

Aldahmesh MA, Mohamed JY, Alkuraya FS. A novel mutation in PRDM5 in brittle cornea syndrome. Clin Genet. 2011 Nov 29. doi: 10.1111/j.1399-0004.2011.01808.x. [Epub ahead of print]

PubMed ID: 
22122778