- Written informed consent/assent of the patient or written informed consent of the parent(s) or the legal guardian(s), depending on the age of the patient, is required prior to any protocol-related procedures being performed; this includes information regarding hematopoietic stem cell transplantation (HSCT) in order to assure that the guardian(s) is fully informed regarding the risks and benefits of this alternative treatment for patients eligible for the trial and who have severe manifestations of MPS I with neurodegeneration.