[Osteogenesis imperfecta, but which one?].

Osteogenesis imperfecta is an heterogeneous group of inherited disorders of type I collagen and of the matrix. Heterogeneity concerns molecular determinism, clinical expression and genetic risk. For the purpose of clinical management, five situations are to be distinguished, according to Sillence classification. Biochemical studies afford a molecular basis for understanding clinical heterogeneity and demonstrate an autosomal dominant transmission in most cases, even the more severe forms.