All MPSs have a remarkably wide phenotypic spectrum (MPS I as example)

This is an example of MPS1. This is a patient with a severe Hurler phenotype.  Again these slight facial dysmorphisms can be seen.  These are twin sisters, with an in-between phenotype which is called Hurler-Scheie. Lastly is a boy with a relatively attenuated Scheie phenotype. Another issue is that when a child grows older, these disorders get worse  because the accumulation of the glycosaminoglycans that cannot be degraded goes on if left untreated. Children with these disorders get sicker later in life.