Achondroplasia is a form of Dwarfism. It is part of the chondrodystrophies or osteochondrodysplasias family which makes bones in a human's skeleton be too short or grow too slowly. It often affects the femur and humerus. It is caused by a dominant allele. That means only one parent has to have the gene. This gives a child a 50% chance of getting the condition. If both parents have the gene the chances are increased to 75%, but it is very unlikely that the child would live more than a few months. However, the condition can also occur without either parent having the gene. Achondroplasia is caused by a change in the DNA for fibroblast growth factor receptor 3. This change affects the making of cartilage. Now that the part of the DNA that causes the condition is known, there is hope that new treatments may be developed.