Autosomal dominant
Caused by changes in one copy of PHIP, a gene in an epigenetic modifier complex, reducing the amount of working protein. Variants are often de novo, but some are inherited from a parent who may be mildly affected.
Signs and symptoms
Developmental delay and intellectual disability or learning difficulties, with behavioural differences such as attention difficulties (ADHD) or anxiety. Overweight or obesity is common from childhood, as are characteristic facial features, such as large ears, prominent eyebrows and a long philtrum. Low muscle tone and visual problems are common.
What a diagnosis changes
Developmental, educational and behavioural support, with attention to diet, activity and weight from an early age. Because changes can be inherited from mildly affected parents, genetic counselling and parental testing help clarify recurrence risk.
Genes analysed
Also known as
Chung-Jansen syndrome; developmental delay, intellectual disability, obesity, and dysmorphic features; DIDOD
