Inclusion Criteria:  Signed inform consent; Verified diagnosis of MPS II (Hunter syndrome); Naïve patients or patients who have received standard ERT whit idursulfase products; No contraindications for lumbar puncture as judged by the Investigator; Willingness and ability to follow study procedures.  Exclusion Criteria:  Clinically pronounced hypersensitivity to ID2S or any other component of the drug product; History of hematopoietic stem cell transplantation (HSCT) or bone marrow transplantation; Implanted or external non-removable metal devices, a cardiac pacemaker, or other objects sensitive to the magnetic field that may pose a danger to both the wearer and the correct operation of magnetic resonance imaging (MRI) equipment; Concomitant diseases and conditions that, in the Investigator's opinion, can put at risk the patient's safety during his/her participation in the study, or which will influence the safety data analysis in case of the disease/condition exacerbation during the study.