Not all people with Hunter syndrome are affected by the disease in exactly the same way; the type and severity of symptoms, age that symptoms appear, and the rate of symptom progression all vary widely.
Hunter syndrome was traditionally categorized into two distinct types, severe and attenuated (now often labeled neuropathic and non-neuropathic), based on the degree of cognitive impairment involved. The severe type was defined by the presence of neurological symptoms alongside physical symptoms, all of which generally become apparent between 2 and 4 years of age. For the attenuated type, minimal cognitive impairment is involved and symptoms may only present in late childhood or early adolescence. However, due to the highly variable nature of Hunter syndrome and variety of presentation between these two types, Hunter syndrome can now be better understood as a spectrum of severity.