What is Chung-Jansen Syndrome?
Chung-Jansen syndrome is a rare disorder- also called PHIP-related disorder. The syndrome is caused by a heterozygous mutation along the PHIP gene. Individuals with this disorder typically have developmental delay, behavioral problems, and are at risk for obesity. At present, the syndrome has been diagnosed in about 300 people worldwide. This number, however, is growing rapidly.
Young children often have feeding difficulties and delayed developmental milestones like rolling, crawling, standing straight and walking. Delayed motor development is partly related to the low muscle tone (hypotonia). Many children and adults with the disorder complain of fatigue and may need to use aids such as a wheelchair. Speech and fine motor skills are often delayed as well.
When children get older (especially through puberty), behavioral problems often manifest themselves. Children can be diagnosed with a developmental and / or behavioral disorder. There may also be issues with irrational fears (anxiety) and problems in the processing of stimuli (sensory integration issues).
Many children become overweight as they get older. This can be related to medication use, but can also be caused by the gene abnormality. How the variation in the PHIP gene causes neurodevelopmental problems and obesity is currently not known.
Just as in any gene disorder, the features and severity of problems can differ greatly between individuals with Chung-Jansen syndrome.