MPS I may present with a wide spectrum of symptoms, depending on how much functional enzyme is produced.

In severe forms, symptoms appear during childhood, and early death can occur due to organ damage.

Children with Hurler syndrome (severe MPS I) may appear normal at birth and develop symptoms over the first years of life.

[citation needed] One of the first abnormalities that may be detected is coarsening of the facial features; these symptoms can begin at 3–6 months of age.

Patients may experience debilitating spine and hip deformities, carpal tunnel syndrome, and joint stiffness.

Patients may be normal height in infancy, but stop growing by the age of 2 years.

[2][3] In less severe cases, (Scheie syndrome, or attenuated MPS I), the presentation can vary considerably.

The reduced production of the enzyme in carriers, however, remains sufficient for normal function; the person should not show any symptoms of the disease.