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.
