Mucopolysaccharidosis Type VI
Are there earlier onset, later onset, or variant forms of Mucopolysaccharidosis Type VI?
There is a severe, rapidly progressing form of Mucopolysaccharidosis Type VI (MPS VI), as well as a milder form of the condition. However, an intermediate stage has also been described by scientists so in reality, the forms of MPS VI cannot be separated into groups, but fall along a spectrum.
Urine testing for glycosaminoglycan (GAG) levels, which is what builds up to harmful levels in MPS VI, will generally show that the higher the level, the more severe the symptoms. However, there is currently no definite way to determine how severe someone's symptoms will be by measuring their urine GAG levels. There is also a test that looks at the ARSB gene, which is the gene that is not working properly in MPS VI, to see what kinds of changes or mutations are causing it to not work. Similar to the urine GAG levels, certain gene changes might suggest severe or milder symptoms, but no definite links have been made.