Morquio syndrome is an extremely rare genetic condition. It is only found when both parents are carriers when the child gets two copies of the gene that causes it, and fewer than one in every 200,000 children is born with the disease. It is a disorder of the processing of mucopolysaccharides, a type of carbohydrate used in the development of body tissue. In the two types of Morquio syndrome, the body doesn’t have enough of one of two enzymes that break down a particular type of mucopolysaccharide called keratan sulfate, the functions of which include cushioning the joints from shock. When it’s not properly broken down, however, the excess can cause significant damage to organs and tissues.
This damage takes a variety of forms. Initial signs typically appear between the ages of 12 months and three years, though prenatal testing can determine if a child will be born with the condition. The condition results in several obvious musculoskeletal indicators, such as a curvature of the spine called kyphoscoliosis, knock-knees, an abnormally large head, coarse facial features with wide gaps in the teeth, a large head, a short trunk, and ribs that flare out at the bottom of the rib cage like a bell. A typical Morquio patient, particularly in cases of type A, will generally be found to have some other, less obvious symptoms, including a heart murmur, an enlarged liver, poor nerve function, or clouding on the corneas of the eyes. If a child shows these symptoms and has not been tested prenatally, the most common test is examining the urine for mucopolysaccharides that were not broken down.
Though cognitive function is not impaired by Morquio, heart failure is a risk, and patients often have respiratory problems as they get older. In addition, underdeveloped and damaged bone structure could cause serious complications, including paralysis. The paralysis risk and related issues can be dealt with surgically. People with Morquio syndrome need to be particularly careful about diet and lifestyle factors associated with heart disease. There is no cure for the condition, though enzyme replacement therapy is being investigated. Symptoms such as respiratory issues and vision problems generally respond to specific treatments.