Mucopolysaccharidosis (MPS) is an inherited metabolic disease in which the body either does not produce enough enzymes required to break down sugars into simpler molecules, or the body produces enzymes that do not work properly. Over time, molecules called glycosaminoglycans (sugar carbohydrates in each of our cells that help build bone, cartilage, tendons, corneas, skin, and connective tissue) collect in the cells, blood, and connective tissues, resulting in permanent, progressive cellular damage. The cellular damage affects the appearance, physical abilities, organ and system functioning, as well as cognitive development.  

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Several different clinical types of mucopolysaccharidosis have been identified.

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MPS I, Hurler, Hurler-Scheie, and Scheie

MPS I is a condition that affects many different organs and tissues. Individuals with severe cases experience a rapid disease progression and a decline in intellectual function. Developmental delay is typically present by age 1, and those severely affected lose basic functional skills and shortened lifespan, sometimes only living into late childhood.

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MPS II, Hunter syndrome

MPS II is a condition that occurs almost exclusively in males. It affects many different organs and tissues. Individuals with a severe form experience a rapid disease progression and a decline in intellectual function, and begin to lose basic functional skills between the ages of 6 and 8 with a life expectancy of 10 to 20 years.

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MPS III, Sanfilippo syndrome

MPS III is a condition that affects the brain and spinal cord, often causing delayed speech, behavior and sleep problems in children. Individuals experience progressive intellectual disability and the loss of previously acquired skills, and in later stages may develop seizures and movement disorders.

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MPS IV, Morquio syndrome

MPS IV is a condition that affects the skeleton, including short stature, knock knees, and abnormalities of the ribs, chest, spine, hips, and wrists. In addition, the cornea typically becomes cloudy, which may cause vision loss or recurrent ear infections may cause hearing loss. The life expectancy of those with severe cases is only until late childhood or adolescence.

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MPS VI, Maroteaux-Lamy syndrome

MPS VI is a condition that causes many tissues and organs to enlarge and become inflamed or scarred.  Skeletal abnormalities are also common. Without treatment, the life expectancy of those with severe symptoms is only until late childhood or adolescence.

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MPS VII, Sly syndrome

MPS VII is a condition that affects most tissues and organs, and can cause various skeletal abnormalities. Severe cases are characterized by hydrops fetalis, a condition in which excess fluid builds up in the body before birth. Most babies are stillborn or die soon after birth, while those who survive may live into adolescence or adulthood. Heart disease and airway obstruction is the major cause of death.

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