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Brittle Cornea Syndrome, Ehlers Danlos Syndrome Type VIB

key information

source: The University of Arizona Health Sciences

summary/abstract:

Clinical Characteristics:

Ocular Features:
This seems to be a subtype of the Ehlers-Danlos syndrome in which the ocular features are prominent. The cornea is thin and can perforate following relatively minor trauma. It is often misshapen as well resulting in keratoglobus and keratoconus. The external appearance can suggest buphthalmos but intraocular pressure is normal. The sclerae are bluish suggesting that the connective tissue defect is more widespread among eye tissues. The lens is not hypermobile, however. This disorder differs from Ehlers-Danlos type VIA (225400) (sometimes called the ocular-scoliotic form) in which there is a defect in lysyl hydroxylase although the ocular phenotype has some similarities.

Systemic Features:
The skin is hyperelastic as in other forms of Ehlers-Danlos and the joints are hypermobile and are susceptible to dislocation. Some but not all cases reported from the Middle East have red hair and it has been suggested this may be part of the syndrome, at least in that part of the world.

Genetics:
A mutation in the ZNF469 gene (16q24), encoding a defective zinc finger protein, is responsible for at least some cases of autosomal recessive brittle cornea syndrome. This confirms its identity as a unique type of connective tissue disease apart from other forms of Ehlers-Danlos in which ocular disease is present (such as type VIA in which the mutation is in the PLOD1 gene).

Homozygous mutations in PRDM5 (4q27) have been found in several families with brittle cornea syndrome 2 (614170).

Treatment:
Treatment beyond corneal repair is limited.

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