A group of 300 people took part in a charity hiking event held on May 6 at Chaoyang Park in Beijing to celebrate Wishbone Day, an international awareness event to highlight osteogenesis imperfecta－a brittle bone disease known as "China doll syndrome".

The participants included 10 sufferers of the genetic condition, supporting members of the public, staff members from the China-Dolls Center for Rare Disorders, the organizers behind the event, as well as volunteers from its partner organizations.

The Beijing center, founded by patients with rare disorders in 2008, is a nonprofit organization that provides care and relief services to OI sufferers and people with other rare diseases.

The center estimates that there are 100,000 people in China affected by OI, one of the lesser-known congenital disorders, which is characterized by fragile bones that are prone to breaking.

Osteogenesis imperfecta is the result of a mutation error of a gene that is responsible for the body's production of collagen, a fibrous protein found in bones and other tissues.

"Collagen in the bones is like what reinforced concrete is to buildings. Without enough concrete, buildings can easily collapse," explains OI expert Wang Yanzhou, director of the pediatric orthopedics department of Shandong Provincial Hospital.

According to Wang, sufferers of the disorder are not only afflicted by the constant threat of multiple bone fractures, but they can also develop other medical issues, such as muscle weakness, hearing loss, fatigue, joint laxity, curved bones, curvature of the spine, blue sclera, brittle teeth and a shortened stature.