Extension Study of HGT-HIT-045 Evaluating Long-Term Safety and Clinical Outcomes of Idursulfase-IT in Conjunction With Elaprase in Pediatric Participants With Hunter Syndrome and Cognitive Impairment

Inclusion Criteria:

- Participant must have completed all study requirements and end of study assessments
for study HGT-HIT-045 prior to enrolling in Study HGT-HIT-046 and must have no safety
or medical issues that contraindicate participation.

- The participant's parent(s) or legally authorized guardian(s) must have voluntarily
signed an Institutional Review Board (IRB)/Independent Ethics Committee(IEC)-approved
informed consent form after all relevant aspects of the study have been explained and
discussed. Consent of the participant's parent(s) or legally authorized guardian(s)
and the participant's assent, as relevant, must be obtained.

- The participant has received and tolerated a minimum of 12 months of treatment with
weekly IV infusions of Elaprase and has received 80% of the total planned infusions
within the last 6 months.

Exclusion Criteria:

- The participant is enrolled in another clinical study that involves clinical
investigations or use of any investigational product (drug or device) other than the
PORT-A-CATH IDDD within 30 days prior to study enrollment or at any time during the
study.

- The participant is unable to comply with the protocol (eg, is unable to return for
safety evaluations, or is otherwise unlikely to complete the study) as determined by
the investigator.

- The participant has experienced an adverse reaction to study drug in Study HGT-HIT-045
that contraindicates further treatment with intrathecal idursulfase-IT.

- The participant has a known hypersensitivity to any of the components of
idursulfase-IT.

- The participant has any known or suspected hypersensitivity to anesthesia or is
thought to be at an unacceptably high risk for anesthesia due to airway compromise or
other conditions.

- The participant has a condition that is contraindicated as described in the
SOPH-A-PORT Mini S IDDD Instructions for Use, including:

1. The participant has had, or may have, an allergic reaction to the materials of
construction of the SOPH-A-PORT Mini S device

2. The participant's body size is too small to support the size of the SOPH-A-PORT
Mini S Access Port, as judged by the investigator

3. The participant's drug therapy requires substances known to be incompatible with
the materials of construction

4. The participant has a known or suspected local or general infection

5. The participant is at risk of abnormal bleeding due to a medical condition or
therapy

6. The participant has one or more spinal abnormalities that could complicate safe
implantation or fixation

7. The participant has a functioning CSF shunt device

8. The participant has shown an intolerance to an implanted device

- The participant has an opening CSF pressure upon lumbar puncture that exceeds 30.0
centimeter (cm) water (H2O).