Dwarfism is a disorder characterized by shorter than normal skeletal growth. There are over 700 different forms of skeletal dysplasia caused by genetic changes that affect bone and cartilage growth. More than 300 different conditions can cause dwarfism, and achondroplasia is the most common type of dwarfism. Achondroplasia is a genetic condition that affects about 1 in 15,000 to 1 in 40,000 people. Most children born with achondroplasia have average-sized parents. Other genetic conditions, kidney disease, and problems with metabolism or hormones can also cause dwarfism. In addition, deficiencies in other hormones or poor nutrition can cause dwarfism. Sometimes the cause of dwarfism is unknown. Growth hormone deficiency is a relatively common cause of proportionate dwarfism. It occurs when the pituitary gland fails to produce an adequate supply of growth hormone, which is essential for normal childhood growth.