A Study of Patients With Sanfilippo Syndrome Type A (MPS IIIA)

Inclusion Criteria:

1a. Documented deficiency in HNS enzyme activity of less than or equal to 10% of the lower
limit of the normal range as measured in fibroblasts or leukocytes (based on normal range
for diagnosis of MPS IIIA by a laboratory that is acceptable to Shire HGT).

AND

1b. Normal enzyme activity level of at least one other sulfatase (to rule out multiple
sulfatase deficiency) as measured in fibroblasts or leukocytes (based on normal range by a
laboratory that is acceptable to Shire HGT).

2.Patient is greater than or equal to 1 year of age and developmental age greater than or
equal to 1 year.

3. Patient is medically stable to accommodate the protocol requirements, including travel
and assessments, without placing an undue burden on the patient/patient's family.

4. Voluntarily signed an IRB/IEC-approved informed consent (assent if applicable) form.
The patient's, patient's parents or legally authorized representative(s) consent and
patient's assent as appropriate, must be obtained.

Exclusion Criteria:

1. Patient has significant non-MPS IIIA-related CNS impairment or behavioral
disturbances, which would confound the scientific integrity or interpretation of
study assessments, as determined by the investigator.

2. Patients who, for MPS IIIA behavioral-related reasons,in the opinion of the
investigator, would preclude performance of study neurocognitive and developmental
testing procedures.

3. Patients who are pregnant, breast feeding, or female patients of childbearing
potential, who will not or cannot comply with the use of an acceptable method of
birth control such as condoms, barrier method, oral contraception, etc.

4. Patient is blind and/or deaf.

5. Patient 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.

6. Patient or patient family history of neuroleptic malignant syndrome, malignant
hyperthermia, or other anesthesia-related concerns.

7. The Investigator may choose to exclude patients who have had complications resulting
from prior lumbar punctures.

8. Patient history of poorly controlled seizure disorder.

9. Patient history of an intracranial pressure (ICP) or opening CSF pressure upon lumbar
puncture that exceeds 30 cm water that has not been definitively treated.

10. Patient is currently receiving psychotropic or other medications which in the
investigator's opinion, would be likely to substantially confound test results.

11. Patient cannot sustain absence from aspirin, non-steroidals, or medications that
affect blood clotting within 1 week prior to a relevant study related procedure (eg,
lumbar puncture if applicable), or has ingested such medications within 1 week before
any procedures in which any change in clotting activity would be deleterious.

12. Patient has received treatment with any investigational drug or device intended as a
treatment for MPS IIIA within the 30 days prior to, or during the study, or is
currently enrolled in another study that involves an investigational drug or device
(enrollment through Safety follow-up contact).

13. Patient has received a hematopoietic stem cell or bone marrow transplant.

14. Patient's assent is unattainable, or the patient's parent(s), or patient's legally
authorized representative(s) is/are unable to understand the nature, scope, and
possible consequences of the study, or do/does not agree to comply with the protocol
defined schedule of assessments.

15. The patient has any item (braces, tattoos, etc.) which would exclude the patient from
being able to undergo MRI according to local Institutional Policy, or the patient has
any other situation that would exclude the patient from undergoing any other
procedure required in this study.