Description

Mucopolysaccharidosis type 1 (MPS 1) is a rare lysosomal storage disease belonging to the group of mucopolysaccharidoses. There are three variants, differing widely in their severity, with Hurler syndrome being the most severe, Scheie syndrome the mildest and Hurler-Scheie syndrome giving an intermediate phenotype. In the severe form (Hurler syndrome or MPS I-H) skeletal deformities and a delay in motor and intellectual development are the leading symptoms. Other manifestations include corneal clouding, organomegaly, heart disease, short stature, hernias, facial dysmorphism and hirsutism. Patients with the adult-onset form (Scheie syndrome or MPS I-S) are of almost normal height and do not show intellectual deficiency. Typical symptoms are stiff joints, corneal opacities, carpal tunnel syndrome and mild skeletal changes. Aortic valve disease can be present. Patients with the intermediate form (Hurler-Scheie syndrome or MPS I-H/S) have normal or almost normal intelligence, but exhibit various degrees of physical impairment. The different phenotypes are caused by allelic mutations in the alpha-L-iduronidase (IDUA) gene (localized to 4p16.3). The mutations result in complete deficiency of the enzyme in Hurler syndrome or partial function in Scheie syndrome, leading to lysosomal accumulation of dermatan sulfate (DS) and heparan sulfate (HS).

External Information

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