Achondroplasia is a genetic disorder that results in short stature. Achondroplasia is a bone growth disorder in which the body does not turn cartilage into bone, especially in the long bones such as in the arms and legs. Known as one of the oldest birth defects, achondroplasia is the most common cause for short stature and disproportionately short limbs. If one parent has achondroplasia their children have a 50% chance of being born with the disorder and in cases where both parents have it, the chance increases to 75%. It is possible however for parents that don't have achondroplasia to give birth to a baby with this condition due to spontaneous mutations. The average height for someone with achondroplasia is about four feet or less. In most case of achondroplasia normal intelligence is present. When a baby has achondroplasia it usually has poor muscle tone which can lead to delays in learning to sit, stand and walk.
