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.
Key Features of USP7-Related Disorders
Developmental and Behavioral Characteristics
- Physical Development:
- Delay in independent walking due to hypotonia and joint hyper-flexibility.
- Approximately 44% have an abnormal gait.
- Learning:
- Learning difficulties often diagnosed as intellectual disability (ID).
- Educational needs range from special education programs to mainstream schooling with an Educational Health Care Plan (EHCP).
- Behavioral Challenges:
- Autistic traits: Hand flapping, repetitive behaviors, skin picking.
- Other behaviors include:
- Aggressiveness.
- Temper tantrums.
- Impulsivity and compulsivity.
- Speech:
- Speech delays; some individuals are non-verbal.
- Language deficits often correlate with the degree of intellectual disability.
Growth and Physical Features
- Growth:
- Short stature affects about one-third of individuals.
- Potential benefit from growth hormone (GH) therapy.
- Facial Features:
- Minor, variable features such as deep-set eyes and a prominent nasal septum.