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.

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Osteogenesis is the process of laying down new bone material by osteoblasts. It occurs in two different ways: Either by Intramembranous Osteogenesis (see intramembranous ossification), which is the direct laying down of bone into the primitive connective tissue (mesenchyme), or by Endochondral Osteogenesis (see endochondral ossification) which involves a cartilage precursor.

The exact mechanisms by which bone delvelopment is triggered remains unclear, but it is thought to involve Growth Factors and Cytokines in some way.

Osteogenesis is bone development.

Osteogenesis Imperfecta is a juvenile bone disease.