Coarse features, shortness of stature, malocclusion, gingival hypertrophy, progressive developmental impairment, pain and limitation of joint motion, dysostosis multiplex cytoplasmic inclusions in fibroblasts (Figure 83.1), deficient intracellular activity of many hydrolases, and elevated activity of these enzymes in serum because of defective post-translational modification of acid hydrolases, a consequence of the fundamental defect in N-acetylglucosaminyl-(GlcNAc) 1-phosphotransferase.