The Dwarf Pony

Mucopolysaccharidosis Type I

Mucopolysaccharidosis type I (defect of the enzyme alpha-iduronidase) is characterized by a broad phenotypic spectrum, ranging from the severe infantile form, called Hurler disease (MPS IH), to the adult form, called Scheie disease (MPS IS), that is associated with an almost normal life expectancy. Typical symptoms in patients with Hurler disease are disproportionate short stature, hepatosplenomegaly, corneal clouding and coarse facial features. Motor and mental development are delayed, without treatment the patients die at the age of around ten years. Patients with Scheie disease have an almost normal stature and no mental retardation, they may have, however, dysmorphic facial features, corneal clouding and joint contractures. Patients whith a clinical phenotype between Hurler and Scheie disease are called Hurler-Scheie-phenotype (MPS IHS). For Hurler patients the treatment of choice is bone marrow transplantation, for MPS IS- and MPS HIS-patients enzyme replacement therapy is available.