What is Hunter syndrome?
Hunter syndrome, also known as mucopolysaccharidosis type II (MPS II), is a condition caused by the body not having enough of a specific enzyme called I2S which breaks down large sugars in the body. There are two forms of Hunter syndrome, which range from mild to severe and typically only affect boys. Boys with the severe form of Hunter syndrome begin to show symptoms of the condition between ages two and four. Symptoms of the condition start with enlargement of the tongue, lips, and vocal cords, and then progress to affect the skin and joints, brain, liver, spleen, heart and other organs.
How common is Hunter syndrome?
About 1 in 35,000 males babies is born with Hunter syndrome in the United States each year.
What can be done for Hunter syndrome?
People with Hunter syndrome can be given can be given a form of treatment that replaces the missing I2S enzyme - this is called enzyme replacement therapy (ERT). Some people with Hunter syndrome are also candidates for stem cell transplants, which can treat other symptoms of the condition. While ERT and stem cell transplant aren’t a complete cure for Hunter syndrome, it can make many of the symptoms less severe, helping people with this condition gain a longer, better quality of life.
How is Hunter syndrome inherited?
Hunter syndrome is caused by changes in the IDS gene. The IDS gene is located on the X chromosome, so Hunter syndrome is called an X-linked inherited condition. Males have one copy of the X chromosome while females have two. For males, a change in the IDS gene on their only X chromosome can cause Hunter syndrome. For females, an alteration in the IDS gene on one X chromosome but a functioning copy on the other X chromosome usually does not result in signs or symptoms of Hunter syndrome. Instead, this female is considered to be a carrier, because she can pass on the X-chromosome with the altered IDS gene to her children. If a baby girl is identified as a carrier for Hunter syndrome through Eli screening, genetic counseling and additional testing in the parents is recommended.