Long-term study of symptoms and progression in people with Sanfilippo syndrome type C

You may qualify if

• ≥1 year and ≤ 25 years of age 2. Confirmed diagnosis of MPS IIIC by all of the following:; Deficiency in the Hgsnat enzyme activity; Genetic analysis demonstrating homozygous or compound heterozygous, pathogenic, and/or potentially pathogenic variants in the Hgsnat gene; Signs/symptoms consistent with MPS IIIC, or individuals who have not presented with signs/symptoms of disease but meet inclusion criteria 2a and 2b 3. Electronic informed consent from legal representative(s) or caregivers and when possible, pediatric or adult assent from the participant 4. One of the legal representative(s) or the caregivers is willing to perform at home visits and assessments per instruction 5. Ability to comply with protocol requirements, in the opinion of the Investigator 6. Able to take food or liquid by mouth, able to walk with or without assistance 7. Participants must have health insurance 8. Caregiver willing and able to comply with protocol requirements, including performing at-home visits and assessments 9. Participants must have smart phone or tablet and reliable internet connection 10. Have one of these languages as their first language: English, Spanish, French, German or Portuguese

You can't join if

• Have received prior gene therapy or ERT for the treatment of MPS IIIC ever or any other investigational drug for any reason within 30 days prior to the Screening visit (Visit 1)
• Have concomitant illness or medical condition that, in the opinion of the Investigator, might compromise the participant's ability to comply with protocol requirements or the participant's wellbeing or safety, or the interpretability of the participant's clinical data