The commonest form of inherited impaired growth. It is a dominant hereditary disorder of ENDOCHONDRAL OSSIFICATION, (see GENETIC DISORDERS) caused by mutations of fibroblast growth factor receptor 3 genes. The long bones of the arms and legs fail to grow properly, while the trunk and head develop normally. Achondroplasia affects both sexes and, while many infants are stillborn or die soon after birth, those who survive have normal intelligence, a normal expectation of life and good health.