Hurler disease (MPS IH) is a progressive disorder. Development and growth are usually normal in the first year, but with ensuing regression it is the most severe mucopolysaccharidosis. The disease is characterised by severe mental retardation, coarse facies, corneal clouding, stiff joints including claw hands, dwarfism, dorso-lumbar gibbus usually in the second or third year, cardiovascular manifestations such as cardiac murmurs and angina pectoris, hepatosplenomegaly, often papilloedema due to communicating hydrocephalus, inguinal and umbilical hernias, glaucoma, rhinorrhea and deafness. Radiologically, after about 18 months the lateral view of the spine shows characteristic beaking of the lower dorsal and upper lumbar vertebrae. The skull may show evidence of hydrocephalus and an enlarged J-shaped sella turcica. Death occurs usually by the end of the first decade. At the milder end of the MPS I clinical spectrum, Scheie disease (MPS IS) is characterised by stiff joints, especially of the hands, aortic incompetence, corneal clouding and normal or high intelligence. Between the two extremes of Hurler’s and Scheie’s diseases there is a continuum of intermediate phenotypes, including the Hurler/Scheie compound type (MPS IH/S) in which patients suffer the severe somatic problems of Hurler’s disease but have normal intelligence.
Enzyme Tests: Deficiency of a-iduronidase is the primary defect in mucopolysaccharidosis (MPS) type I (Hurler and Scheie diseases and intermediate phenotypes).