Osteogenesis imperfecta (OI and sometimes known as brittle bone disease, or "Lobstein syndrome") is a genetic bone disorder. People with OI are born with defective connective tissue, or without the ability to make it, usually because of a deficiency of Type-I collagen. This deficiency arises from an amino acid substitution of glycine to bulkier amino acids in the collagen triple helix structure. The larger amino acid side-chains create steric hindrance that creates a bulge in the collagen complex, which in turn influences both the molecular nanomechanics as well as the interaction between molecules, which are both compromised. As a result, the body may respond by hydrolyzing the improper collagen structure.