People with MPS diseases lack an enzyme in their lysosomes, which usually breaks down complex molecules, known as GAGs (glycosaminoglycans), into smaller parts to be recycled (lysosomes are small pockets within cells, which recycle molecules that the cell no longer needs). Without this enzyme, these GAGs accumulate in the cells of patients with MPS, which eventually build up and lead to organ damage and the related symptoms of MPS. The MPS diseases are a type of ‘lysosomal storage disease’. There are seven clinical types of MPS disease; one example is MPS II, which is also known as Hunter syndrome. All MPS diseases are genetic disorders, meaning they can be inherited from parents—parents are often ‘carriers’ of the disease, meaning they possess the MPS gene but do not show symptoms. MPS II is slightly different because it mainly affects boys (although a very small number of MPS II girls have been reported worldwide) and the mother is almost always the carrier—as a result, male relatives on the mother’s side of the family may also have MPS II.

• MPS I, II and VII have generally similar disease profiles that can include a wide range of symptoms, affecting many parts of the body, e.g., airways, ears, hernia, facial features, skeleton and joints, eyes, liver, heart, and, in some patients, the brain is affected.
• MPS III is different because the brain is the main body organ that is affected.
• MPS IV and VI are different because they don’t often affect the brain.
• Only a handful of MPS IX cases have been documented; therefore, it is not possible to know the full disease profile. 
  
  Take Arian, for example, who has MPS type 2 (also known as MPS II or Hunter syndrome). By the time Arian was three years old, he had constant ear infections and finger stiffness. Having repeat ear infections could be considered normal for a child this age from mixing with other children in school. For the joint stiffness, he was referred to a physiotherapist. A check-up later revealed a heart murmur, and in the following referral, a heart valve problem was revealed. However, it wasn’t until referral to another doctor who noticed differences with his bones and skeleton that they began to suspect that MPS II was causing all his symptoms. You can read more of Arian’s story here. Arian had several MPS II symptoms, but looking at the symptoms individually, it was hard to know that MPS II was causing them. The key sign that it was MPS II was the fact that they were happening at the same time. Together we can help raise awareness of the symptoms of MPS diseases to help people like Arian’s family and doctors #ChaseTheSigns of MPS II.