Introduction

• Definition:
  • USP7-related disorder, also known as Hao-Fountain Syndrome (HFOUS), results from pathogenic variants or deletions in the USP7 gene.
  • The USP7 gene is located on chromosome 16p13.2 and encodes ubiquitin-specific protease 7, a key enzyme regulating protein ubiquitination and recycling.
• Clinical Presentation:
  • Affects both boys and girls, with variability in severity.
  • Common features include:
    • Neurodevelopmental difficulties: Developmental delay, intellectual disability (ID), and behavioral issues.
    • Speech and language delays.
    • Seizures.
    • Hypotonia (low muscle tone).
    • MRI abnormalities.