An unusually genetic disorder of bone growth that leads to short stature. Persons with achondroplasia have a protruding forehead on a head of a normal size, a well developed trunk and short limbs.
The condition is created by a defect of a dominant gene but usually arises as a new mutation rather than being inherited from a parent. The long bones of the arms and the legs are affected mainly. The cartilage that links each bone to its epiphysis (the growing area at its tip) is changed to bone too early thereby preventing further limb growth.
Achondroplasia is usually obvious at birth or during the infants first year of life and no treatment is available to change the situation. Intelligence and sexual development are not affected and lifespan is close to average.