We speculate that this is because PYD originates from both bone and cartilage, but DPD is from only bone,52, 53 and would suggest that chondrocyte abnormalities leading to abnormal endochondral growth and increased cartilage turnover, more so than abnormal bone modeling/remodeling, play a significant role in the development of short stature in children with MPS I. The gene discussed is DPYD; the disease is Scheie syndrome.