The coarse facial features have been described as "Hurler-like". Two major types have been described: type 1 with onset in the first 6 months of life and rapid psychomotor and general neurologic deterioration, and the later onset, less severe type 2 in which angiokeratomas resembling Fabry disease occur. Infants with type 1 may not survive beyond one year of age. The Hurler-like face is less pronounced and the neurologic deterioration is less rapid in type 2 with survival often into the third decade or later. The intracellular accumulation of glycolipids and glycoproteins leads to cell death accounting for the progression of CNS disease. Abnormal bone growth (dysostosis multiplex) can lead to short stature. Elevated sweat NaCl, hypohidrosis, and poor temperature control can be a feature of both types but this is more pronounced in type 1. The DNA mutation is the same in both types and there may be overlap in some of the clinical features. Furthermore, both types have been reported in the same family.
Low levels of alpha-L-fucosidase can be detected in plasma, urine, and leukocytes. Glycolipids and glycoproteins have also been shown to accumulate in the cells of the skin, liver, spleen, pancreas and kidneys.
