Group of connective-tissue diseases in which the bones are very fragile. Several forms probably reflect different degrees of expression of the same disorder. Persons with osteogenesis imperfecta type I are normal at birth, but fractures occur easily; in van der Hoeve syndrome the sclerae are bluish, bone deformities in the skull cause deafness, double-jointedness occurs, and skin is abnormally thin. Babies with osteogenesis imperfecta type II, if not stillborn, are born with fractures, and fractures continue to occur, causing severe crippling; survival to adulthood is rare