A group of disorders passed through families in which bones break easily, sometimes for no known reason.

Osteogenesis imperfecta is caused by gene changes. These genes affect how the body makes a protein called collagen that is needed for bone strength. There are a number of types of the condition, ranging from mild to severe.

Symptoms depend on type. Symptoms can be mild, with only a few broken bones in a lifetime. Some people have hundreds of broken bones in their lifetime, including in the womb. Some babies die at birth or shortly after birth.

Treatments include bone-strengthening medicines and occupational and physical therapy. Many children have orthopedic surgery to place metal rods into bones to make them stronger.