An abnormal collagen α chain containing cysteine in autosomal dominant osteogenesis imperfecta

Abstract

The brittle, osteoporotic bones that characterise osteogenesis imperfecta often mask more generalised changes in connective tissue. These may develop in the skin, which is often soft and hyperextensible, and the eyes, where the scleras are often blue owing to their reduced thickness. Umbilical and inguinal hernias, joint hypermobility, floppy mitral valves, blood vessel fragility, and poor dentition have also been noted. The disease is clinically variable; Sillence et al have classified four major subgroups based on mode of inheritance and disease severity, but each of these groups appears to be heterogeneous. The clinical variability and the diversity of the changes in connective tissue suggest a group of generalised molecular defects. Recently biochemical investigation of the disease has shown a number of abnormalities of collagen, the major structural protein of connective tissues. The recognition of these abnormalities is important for the clinical understanding of the disease and in assessing its potential for prenatal diagnosis. We report one form of osteogenesis imperfecta designated type I by Sillence that is characterised by an abnormal collagen α chain containing cysteine.