Mucopolysaccharidosis type IVA (MPS IVA, also called Morquio syndrome, type A) is a metabolic condition that primarily affects the skeleton. The severity, age of onset, and associated symptoms vary significantly from person to person and range from a severe and rapidly progressive, early-onset form to a slowly progressive, later-onset form. The more severe form is usually diagnosed between ages 1 and 3, while the milder form may not become evident until late childhood or adolescence. Symptoms include various skeletal abnormalities such as short stature, knock knees, pectus carinatum, and malformations of the spine, hips and wrists. There may be involvement of other organ systems such as respiratory problems, valvular heart disease, hearing impairment, corneal clouding, dental abnormalities, hepatomegaly, and spinal cord compression. MPS IVA is caused by changes in the GALNS gene and is inherited in an autosomal recessive manner.