Chung-Jansen Syndrome

Ongoing Study

Patients, parents and caregivers can register.

Dr. Chung has held an online presentation about her ongoing study into the PHIP-gene abnormalities.
She calls on patients or their parents/caregivers to register for her study and emphasizes the importance of participation.

For detailed information about this study please visit the Research page

Chung-Jansen Syndrome

What is it?

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. 

Just as in any gene disorder, the features and severity of problems can differ greatly between individuals with Chung-Jansen syndrome.

Psychological Development and Behavioral Disorders

Behavioral problems are a striking and profound characteristic of the Chung-Jansen syndrome that children and adults have to deal with. This concerns rebellious and sometimes even (verbally) aggressive behavior that may be related to a developmental or behavioral disorder and / or learning delay.

The following developmental and / or behavioral
disorders may occur:

ASD (Autism)

Anxiety Disorder


Sensory Processing Disorder


DCD / Dyspraxia

Learning Difficulty and Intellectual Disability

Children with the syndrome are more hindered in learning gross and fine motor skills than other children of the same age.
Children sometimes seem lazy and stubborn, but frustration about not being able to perform a certain task often lies behind this behavior.
There often is a gap between verbal and performal skills. Individuals with the syndrome are verbally well developed. Because of this gap, the capabilities of children and adults are often overestimated which can increase fatigue and behavioral problems.


People with Chung-Jansen syndrome often have recognizable facial features, also called dysmorphic features.

The most common facial features are:

  • Eyebrows (almost) fused together (synophris);
  • Full eyebrows;
  • Crease at the eyes (epicanthal folds);
  • Upturned nose;
  • Large ears and fleshy ear lobes;
  • Fusion of the skin between the second and third toe (cutaneous syndactyly);
  • A curved little finger (clinodactyly);
  • Tapered fingers;
  • Light brown spots on the skin (cafe au lait spot).

Physical Problems

Although physical problems do not predominate in this syndrome, there are certainly impactful limitations.

The following physical limitations may occur:

Eye Disorder

Low Muscle Tone

Gastrointestinal Problems

Skeletal Problems


Abnormality and Problems with the Kidneys


The syndrome is caused by a defect in the the PHIP gene encoding the pleckstrin homology domain-interacting protein. The PHIP gene is located on chromosome 6. Individuals normally have two chromosomes 6 with two copies of the PHIP gene. Individuals with Chung-Jansen syndrome have a defect in one of the two copies.