Neuroinflammation and oxidative stress have been shown to be present in persons with mucopolysaccharidosis type I (MPS I), but their effect on disease severity and disease progression is unknown. The investigator intends to employ brain magnetic resonance spectroscopy (MRS), a non-invasive technique, along with analysis of neuroinflammation and oxidative stress biomarkers in the blood, to measure and determine the level of oxidative stress and neuroinflammation, and their impact on clinical variability in MPS I patients.

Persons with MPS I have a wide range of clinical manifestations including central nervous system (CNS) impairment. The role of neuroinflammation and oxidative stress is one avenue of investigation which may clarify the broad neurological impairment in MPS I. Finding biomarkers that accurately describe the underlying and ongoing brain pathology is a key not only to understanding the disease, but also to understanding the possibility of new therapeutic approaches for MPS I patients.

The investigator will compare patients with Hurler syndrome, and Hurler-Scheie or Scheie syndrome, with healthy controls. There will be 10 participants in each group, resulting in a total of 30 participants. Within the Hurler-Scheie or Scheie syndrome group, the investigator will examine the association of clinical severity with the proposed measures. These findings might help determine whether hematopoietic cell transplantation (HCT), which is the treatment for Hurler syndrome patients, results in decreased oxidative stress and neuroinflammation as compared to Hurler-Scheie or Scheie syndrome patients, who are treated by enzyme replacement therapy (ERT). Additionally, these findings might help determine whether therapies directed at reducing neuroinflammation and oxidative stress in MPS I could enhance neurological outcomes.

Study hypothesis: neuroinflammation and oxidative stress are present in MPS I subjects and are reflective of disease severity.

Inclusion Criteria:

MPS I participants must meet the following:

1. Diagnosis of Hurler syndrome, OR Hurler-Scheie syndrome, OR Scheie syndrome
2. 6 years of age or older at time of screening

Healthy control participants must meet all of the following:

1. Absence of neurological disorder
2. 6 years of age or older at time of screening

Exclusion Criteria:

Persons who have any of the following will not be enrolled in this study:

1. Any surgically implanted pacemaker
2. Any indwelling electronic device, including programmable shunts
3. Orthodontic braces, unless non-metallic
4. Other implanted metal in the body other than titanium
5. An inability or unwillingness to complete an MRI/MRS because of low cognitive function or behavioral dysregulation
6. Pregnancy

20 subjects who have MPS I and are 6 years of age or older will be recruited for this study: 10 with severe MPS I (post-HCT Hurler syndrome); and 10 with attenuated MPS I (Hurler Scheie or Scheie syndrome, and receiving ERT).

In addition, 10 normal healthy controls, 6 years of age or older, will be recruited for this study.

De-identified individual data is input to the NIH-funded Rare Diseases Clinical Research Network's Data Management & Coordinating Center ("DMCC"). Eventually this data will become part of the database of Genotypes and Phenotypes ("dbGaP"), which is part of the National Center for Biotechnology Information, U.S. National Library of Medicine.

De-identified individual data are input to the NIH-funded Rare Diseases Clinical Research Network's Data Management & Coordinating Center ("DMCC") as these data become available following participants' appointments. After the conclusion of this study and analysis of its data, these data will become part of the database of Genotypes and Phenotypes ("dbGaP"), which is part of the National Center for Biotechnology Information, U.S. National Library of Medicine. These data will remain available in this database indefinitely.

Access criteria are determined by the National Center for Biotechnology Information, U.S. National Library of Medicine.