The defect in Hurler and Hunter syndromes. II. Deficiency of specific factors involved in mucopolysaccharide degradation.

Cultured fibroblasts, derived from patients with the Hurler and Hunter syndromes, show defective degradation of sulfated mucopolysaccharide. The aberrant metabolism of Hurler cells can be corrected by secretions of fibroblasts of genotype other than Hurler, and similarly, the defect of Hunter cells can be corrected by secretions of fibroblasts of genotype other than Hunter. The active factors in these secretions, which are heat labile and associated with macromolecules, accelerate the degradation of mucopolysaccharide.