Endocrine Abstracts

Osteogenesis imperfecta (OI) is a heterogeneous genetic disorder with a prevalence of 1/15 000 to 1/20 000 individuals. In more than 90% of patients with type I–IV OI, the disorder is due to a dominant mutation in one of the two genes that encode the α chains of collagen type I, Col1A1 and Col1A2. Collagen type I is present in many tissues, and in addition to multiple fractures patients with OI can have dentinogenesis imperfecta, blue sclera, hyper mobile ligaments and skin, hearing loss and increased risk of bruising. Classically, OI is divided into four subtypes, Sillence class I–IV, with the addition of three more rare forms. Type I is the most common and is generally mild and non-deforming. Type II is the most severe and is lethal already in the perinatal period, usually due to respiratory insufficiency from multiple thoracic fractures. Type III is severely deforming and patients often have fractures at birth. Type IV has a clinical range between type I and III and thus is moderately deforming. Recently described types V–VII are rare and lead to a moderate to severe phenotype. The majority of patients with OI have a low BMD.

To date there is no cure for OI. Many patients are treated with bisphosphonates, which there is support for in clinical trials, most of these are in children with OI. It is not known if treatment with other osteoporosis drugs would be a better alternative or a perhaps a complement to bisphosponates in the patient with OI. A therapeutic vision is to use either stem cell therrapy or silencing of the mutated genes through RNA interference (RNAi).

In this presentation the litterature concerning effects of antiosteoporotic drugs in adult patients with OI will be revived.