rare sex-linked hereditary disorder that varies widely in its severity but is generally characterized by some degree of dwarfism, mental retardation, and deafness. The disease affects only males and makes its first appearance during the first three years of life. Many patients die before age 20. Speech and mental development are delayed, the child has frequent respiratory infections, and as the disease progresses a typical constellation of physical signs becomes evident: protuberant abdomen, claw hands, excessive hair growth, coarsening of the face, and retarded growth. The disorder is caused by a deficiency in the enzyme iduronate sulfatase. This deficiency results in a defective chemical breakdown of the mucopolysaccharides, carbohydrates essential in the development of the connective tissues, and a consequent accumulation of mucopolysaccharides in the body, which in turn causes the disease's characteristic mental and physical defects.