Collagen maturation defects in Ehlers-Danlos keratopathy.

Ehlers-Danlos syndrome is one of many inherited abnormalities of connective tissue, specifically collagen. A 16-year-old caucasian female with Type VI Ehlers-Danlos syndrome had five unusual corneal findings, four of which have not been reported in association with Ehlers-Danlos syndrome: micro-cornea (previously reported), cornea plana, keratoconus posticus, stromal haze at the level of Bowman's layer and a peripheral ring opacity suggestive of anterior embryotoxon. Type VI Ehlers-Danlos syndrome is associated with deficient activity of lysyl hydroxylase which ultimately is responsible for cross-linking collagen chains, the source of its tensile strength. Genetic regulation of procollagen formation is believed to be mediated by mRNA. Aggregation and maturation in the extracellular matrix is probably influenced and mediated by its evolving biochemical environment, particularly by complex carbohydrate moieties. An understanding of collagen maturation, and the pathophysiologic and biophysical consequences of abnormalities at this level of biochemical organization, permits more specific understanding of ocular dysmorphology and collagen diseases.