Hunter syndrome is a rare genetic disease that almost always occurs in males. This incurable disease is also called mucopolysaccharidosis II (MPS II). This disorder is caused by the deficiency of the lysosomal enzyme iduronate-2-sulfatase (I2S). This enzyme is needed to successfully break down glycosaminoglycans, as part of the body’s normal recycling and renewal process. In a person with Hunter syndrome, enzyme I2S is missing or not working correctly. It is the accumulation of undigested glycosaminoglycans within the body’s tissues that eventually causes permanent, progressive damage affecting appearance, mental development, organ function and physical abilities (MayoClinic). MPSII is a spectrum disorder with mild at one end and severe at the other- 75% are severe.
In the United States, it is estimated that MPS II occurs in about 1:100,000 males born. This is an X-linked recessive disease -mother is a carrier of the defective gene. Depending on the severity of the MPS II, mental development eventually plateaus and begins to regress usually in the preschool years and growth (height) stops by age eight. Individuals with the severe form of MPS II usually die during their teen years.
Signs and symptoms –begin to appear as early as 18 months of age include: *recurrent ear/respiratory infections *enlarged head *coarsened facial features *distended abdomen –enlarged liver and spleen *hernias *irregularly shaped teeth
* Respiratory –restrictive lung disease, blocked airways, and sleep apnea * Cardiovascular –high blood pressure, leaky heart valves * Neurologic – developmental delay, seizures, hydrocephalus * Hearing loss * Vision –peripheral vision loss, night blindness * Difficult swallowing –poor jaw mobility, enlarged tonsils, adenoids and tongue * Musculoskeletal – contractures, stiff and painful joint movement, carpal tunnel syndrome, scoliosis, wide-spread bone