http://naglazyme.com/hcp/about-mps-vi-2/diagnosing-mps-vi/

To the non-trained eyes sometimes these can go unnoticed for a long time. The reason why is that because the disease is progressive, patients are born normally looking and as they get older they start developing these features, which is illustrated here with this patient who wouldn’t be seen as looking dysmorphic or coarse at birth but by 10 years later she looks completely different. This is because that substrate is accumulating in the bones and in the connective tissue and it’s causing that change in appearance, that coarseness. Some other LSDs never develop that coarseness, they can look normal even if they grow up.