Achondroplasia is a growth disorder caused by a specific genetic mutation. As a result, cartilage has difficulty converting to bone, which usually results in dwarfism. Although there is no cure for achondroplasia, treatments are available to help relieve symptoms and health conditions (such as breathing problems) that are often associated with this disorder.

What Is Achondroplasia?

Achondroplasia is one of the most common causes of dwarfism. Characteristics of a person with the disease include:  

• A short stature with proportionately short arms and legs
• A large head
• A prominent forehead
• A flattened bridge of the nose.

  Achondroplasia is a bone growth disorder. Although the word literally means "without cartilage formation," the problem is not the formation of cartilage. The problem occurs when the cartilage has difficulty converting to bone, especially in the long bones of the arms and legs.  

Signs and Symptoms of Achondroplasia

All people with achondroplasia have a short stature. The average height of an adult male with the condition is 131 centimeters (52 inches, or 4 foot 4 inches), and the average height for an adult female is 124 centimeters (49 inches, or 4 foot 1 inch).   Characteristic symptoms include:  

• An average-size trunk.
• Short arms and legs, with particularly short upper arms and thighs.
• An enlarged head (macrocephaly), with a prominent forehead.
• Fingers that are typically short. The ring finger and middle finger may diverge, giving the hand a three-pronged (trident) appearance.

  (Click Symptoms of Achondroplasia for more information.)