Mucopolysaccharidosis Type VI
Is there variable expression or incomplete penetrance in Mucopolysaccharidosis Type VI?
Different people with mucopolysaccharidosis type VI (MPS VI) will have different symptoms and different severities of disease. 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.