Natural History to Assess Disease in Patients With MPS IIIC (C-RARE) | MPS IIIC | Observational Study | UT Southwestern Children’s Medical Center

Page last updated: July 17, 2026

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Study Summary

This is a REMOTE prospective observational study of participants with Sanfilippo Syndrome Type IIIC (MPS IIIC). Patients’ functional abilities will be captured using video recordings taken by patients’ legal representative or caregiver using a dedicated clinical video application downloaded from the internet onto a smartphone. The video application is called C-RARE.

Electronic observer-reported outcome (ObsRO) questionnaires will be completed by the legal representatives or caregivers via C-RARE. The study will last two years with videos and questionnaires taken every 6 months for a total of 5 time points. Data will then be reviewed and measured for functional change using a scoring scale designed for the use of this study.

Study Title: Natural History to Assess Disease in Patients With MPS IIIC (C-RARE)

Trial Listing: Read this clinical trial’s information on ClinicalTrials.gov, for more details including contact information to reach out to the study sites, full inclusion and exclusion criteria. We encourage you to check the Clinicaltrials.gov link frequently for updates on possible new study sites and changes in enrollment status or criteria.

Study Status: Not yet recruiting

Number of participants: estimated 35 children with MPS IIIC, ages 12 month old to 25 years old

Duration: Patients will be studied for 24 months

The study will be conducted remotely; no in-person visits are required. Approximately 35 participants with MPS IIIC will be enrolled in the study through a study site in the United States of America (USA). Enrollment of the first 25 participants with age ≤10 years will help ensure that the data collected from these younger participants will provide a better understanding of the early phase of the disease that may be relevant for future drug development. The remaining 10 participants will be between 11 to 25 years of age. The cutoff for the study is 25 years old. Participants speaking either Spanish, Portuguese, German, French or English may enroll in the study.

Location:

• The University of Texas Southwestern Medical Center, Dallas, Texas, United States of America

Qualifications to Participate:

• Inclusion Criteria | To be eligible to participate in the study, patients must meet all of the following criteria:
  1. Age ≥1 year and ≤ 25 years of age
  2. Confirmed diagnosis of MPS IIIC by all of the following:
     1. Deficiency in the Hgsnat enzyme activity
     2. Genetic analysis demonstrating homozygous or compound heterozygous, pathogenic, and/or potentially pathogenic variants in the Hgsnat gene
     3. Signs/symptoms consistent with MPS IIIC, or individuals who have not presented with signs/symptoms of disease but meet inclusion criteria 2.1 and 2.2 above.
  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
• Exclusion Criteria | Patients who meet any of the following criteria will not be eligible to participate in the study:
  • 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