Brittle cornea syndrome and its delineation from the kyphoscoliotic type of Ehlers-Danlos syndrome (EDS VI): report on 23 patients and review of the literature

Abstract

The brittle cornea syndrome (BCS) is a generalized connective tissue disorder characterized by corneal rupture following only minor trauma, keratoconus or keratoglobus, blue sclerae, hyperelasticity of the skin without excessive fragility, and hypermobility of the joints. It is inherited as an autosomal recessive trait but the underlying genetic defect remains undetermined. We present 23 patients (11 male) from 13 nuclear families followed at the King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia, aged 3-28 years at last follow-up. A total of 28 events of corneal rupture were noted in 17 patients (eight male), among whom nine had had bilateral ruptures, and eight had had unilateral ruptures (four of the right cornea), while two had experienced re-rupture 2 and 4 years, respectively, after surgery; six patients (aged 3-21 years) had had no ruptures. We describe the natural history of our cases and discuss them together with those others reported in the literature. Because of similarities between the BCS and the kyphoscoliotic type of the Ehlers-Danlos syndrome (EDS VI), both disorders tend to have been confounded. Here, we show that all of our BCS patients tested in this regard had biochemical findings reflective of normal activity of lysyl hydroxylase, characteristically deficient in EDS VI, such as normal urinary total pyridinoline ratios and/or normal electrophoretic migration of collagen chains produced by dermal fibroblasts. The BCS is, therefore, an entity distinct from the kyphoscoliotic type of EDS, which has a much poorer prognosis.