one of several rare genetic disorders involving a defect in the metabolism of mucopolysaccharides, the class of polysaccharides that bind water to unite cells and to lubricate joints. Onset of the syndrome is in infancy or early childhood, and the disease occurs with equal frequency in both sexes. Affected individuals exhibit severe mental retardation, clouding of the corners of the eyes, deafness, hirsutism (hairiness), enlarged liver and spleen, dwarfism with hunched back, short limbs and clawed hands, a large head with wide-set eyes, heavy brow ridges and deep bridge of nose, and poorly formed teeth. The disorder is identifiable within two years of birth; such children require institutional care and usually do not live beyond adolescence. Death most often results from heart failure, which is attributable to infiltration of heart muscle and coronary vessels with mucopolysaccharides.