Osteogenesis imperfecta (OI) is a connective tissue disorder characterized by bone fragility and low bone mass. Due to considerable phenotypic variability, a classification of OI subtypes based on clinical features and disease severity has been developed: OI type I, with blue sclerae; perinatal lethal OI type II, also known as congenital OI; OI type III, a progressively deforming form with normal sclerae; and OI type IV, with normal sclerae. Most forms of OI are autosomal dominant with mutations in one of the 2 genes that code for type I collagen alpha chains, COL1A1  and COL1A2. OI8 is caused by homozygous or compound heterozygous mutation in the LEPRE1 gene on chromosome 1p32. [From OMIM]