Mucopolysaccharidosis Type II
What is mucopolysaccharidosis type II (MPS II) disease?
Mucopolysaccharidosis type II, also known as Hunter syndrome and MPS II, is a progressive (disease that gets worse with time) genetic syndrome in the category of lysosomal storage diseases that primarily affects boys. Rarely, girls have also been diagnosed with this disease.
Individuals with MPS II are not able to break down a sugar molecule called glycosaminoglycan (GAG) in their cells to smaller molecules because they are missing an enzyme called Iduronate 2-sulfatase or I2S. This causes the GAG molecules build up in a compartment of the cell called the lysosome, and it to stop working, causing the symptoms and features of MPS II.
As the disease progresses, other organs and tissues are effected by the build up of GAG molecules. The brain and heart are two major organs affected in MPS II, as well as problems with breathing due to blocked or restricted airways.
There are two major types of MPS II, the early progressing type and the slowly progressive type. One of the major differences between these two types of MPS II is how the brain is affected by the disease. In the early progressing type, individuals may experience regression or loss of milestones and cognitive development between 6 to 8 years of age, and pass away by 20 years of age. In the slowly progressing type, cognitive abilities may be in the normal range and individuals may live into adulthood.
The best person to figure out if someone may have MPS II is a geneticist (doctor with special training in genetics), or other doctor with special training and experience in lysosomal storage disorders and MPS. You can ask your primary doctor for a referral or recommendation. The American College of Medical Genetics and Genomics (ACMG) also has a "Find a Genetics Clinic" search function that can help you find a genetics specialist near you. ACMG Find a Genetic Service