Hunter's disease or Mucopolysaccharidosis II (MPS II) is an extremely rare inherited disease that only occurs in males. A person who has MPS II is deficient in the Iduronate 2-Sulfatase protein, which is essential in breaking down dermatan sulphate and heparin sulphate. When the amount of dermatan sulphate is high, the severity of physical symptoms are higher, and when the amount of heparin sulphate is high, the severity of brain symptoms are higher. Sadly, MPS II is a non-curable disease that is almost always fatal.
The mutation occurs in the iduronate sulfatase protein coding gene, located in the long arm of the x-chromosome. This gene produces the protein iduronate 2-sulfatase.
Hunter's Syndrome was named after Charles Hunter, who discovered the disease in 1917. Hunter diagnosed two brothers in Manitoba, Canada. He recognized the large skull and oar-shaped ribs. His disease is extremely rare. Only about 1:136,000 male births have the disease in the US, and 1:100,000-150,000 male births world wide. This statistic only includes males because females are not effected by this disease.
A 2-4 year old person with MPS II may experience many different symptoms. These symptoms include lard rounded cheeks, a broad nose, an enlarged head, or an enlarged tongue. The vocal cords may also swell, causing a deep and hoarse voice. This disease may also narrow the airway, potentially causing upper respiratory problems and/or sleep apnea.
Picture 1: The following are pictures of the large rounded cheeks some patients experience.
Picture 2: This is a picture of the enlarged head symptom.
Changes in facial features are usually the first diagnosis. Blood, urine, and tissue samples can be used to test for the deficient enzyme. This test can also show excessive amounts of complex sugar involved with the disease. Hunter's Syndrome cannot be cured, but treatments can be used to increase the patients standard of living. Doctors can help open the airway, relieving respiratory conditions. Also, surgery can be done to replace damaged heart valves if the patient is showing major cardiovascular problems.
The prognosis for somebody diagnosed with MPS II will be either severe or mild. A person with severe MPS II will lose intellectual function, and contract diseases faster. At around age 6-8, they will lose basic functioning skills. Sadly, the life expectancy for somebody with severe MPS II is 10-20. The mild MPS II is a lot less powerful. Yes, their life span will be shortened, but they will not lose intellectual function, and will live into their adult hood.
The genetic pattern of inheritance is X-linked, and recessive. The disease is only present in males.
Picture 3: This is a visual of the chances an offspring has of being diagnosed with this disease. A woman who carries the disorder as a 1/4 chance of having an unaffected male, 1/4 chance of having an affected male, a 1/4 chance of having a carrier female, and a 1/4 chance of having an unaffected female.
There has been much current research on enzyme and gene therapies that can slow the progress of the disease, and lessen its severity. Enzyme therapy is when man-made or genetically engineered enzymes are used to replace defective enzymes and ease the disease symptoms. Enzyme therapy is given through an IV line. Although many doctors believe it will increase the patient’s standard of life, it does have some negatives. It has caused serious allergic reactions, and other minor symptoms. Gene therapy is another new treatment, but needs more work until it could be used on real patients. It replaces the chromosome that creates the missing enzyme, and could potentially be the cure.
Title Picture: Harper, Isabel. “Isabel Harper.” Pinterest, www.pinterest.com. Accessed 5 Feb. 2017.
Information: “IDS Iduronate 2-sulfatase.” National Center for Biotechnology Information, 25 Jan. 2017, www.ncbi.nlm.nih.gov. Accessed 5 Feb. 2017.
Picture 1 and 2 plus information: “Mucopolysaccharidosis Type 2.” Genetics Home Reference, U.S. National Library of Medicine, 31 Jan. 2017, ghr.nlm.nih.gov. Accessed 5 Feb. 2017.
Picture 3 plus information: Staff, Mayo Clinic. “Hunter Syndrome.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 2017, www.mayoclinic.org. Accessed 5 Feb. 2017.