The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.
| Signs and Symptoms | Approximate number of patients (when available) |
| Abnormality of creatine metabolism | Very frequent (present in 80%-99% of cases) |
| Delayed speech and language development | Very frequent (present in 80%-99% of cases) |
| Intellectual disability | Very frequent (present in 80%-99% of cases) |
| Seizures | Very frequent (present in 80%-99% of cases) |
| Aganglionic megacolon | Frequent (present in 30%-79% of cases) |
| Ataxia | Frequent (present in 30%-79% of cases) |
| Athetosis | Frequent (present in 30%-79% of cases) |
| Autistic behavior | Frequent (present in 30%-79% of cases) |
| Cachexia | Frequent (present in 30%-79% of cases) |
| Chorea | Frequent (present in 30%-79% of cases) |
| Constipation | Frequent (present in 30%-79% of cases) |
| Dystonia | Frequent (present in 30%-79% of cases) |
| Hyperactivity | Frequent (present in 30%-79% of cases) |
| Hypertonia | Frequent (present in 30%-79% of cases) |
| Ileus | Frequent (present in 30%-79% of cases) |
| Malar flattening | Frequent (present in 30%-79% of cases) |
| Muscular hypotonia | Frequent (present in 30%-79% of cases) |
| Open mouth | Frequent (present in 30%-79% of cases) |
| Self-mutilation | Frequent (present in 30%-79% of cases) |
| Joint hyperflexibility | Occasional (present in 5%-29% of cases) |
| Mask-like facies | Occasional (present in 5%-29% of cases) |
| Microcephaly | Occasional (present in 5%-29% of cases) |
| Ptosis | Occasional (present in 5%-29% of cases) |
| Redundant skin | Occasional (present in 5%-29% of cases) |
| Abnormality of metabolism/homeostasis | - |
| Aggressive behavior | - |
| Attention deficit hyperactivity disorder | - |
| Broad forehead | - |
| Delayed myelination | - |
| Exotropia | - |
| Failure to thrive | - |
| Feeding difficulties in infancy | - |
| Gait disturbance | - |
| Hypermetropia | - |
| Hypoplasia of the corpus callosum | - |
| Impaired social interactions | - |
| Infantile onset | - |
| Joint hypermobility | - |
| Long face | - |
| Midface retrusion | - |
| Motor delay | - |
| Myopathic facies | - |
| Narrow face | - |
| Neonatal hypotonia | - |
| Pes cavus | - |
| Poor hand-eye coordination | - |
| Spasticity | - |
| Tall stature | - |
| Underfolded superior helices | - |
| Vomiting | - |
| X-linked recessive inheritance | - |
Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.
The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.
Nonprofit support and advocacy groups bring together patients, families, medical professionals, and researchers. These groups often raise awareness, provide support, and develop patient-centered information. Many are the driving force behind research for better treatments and possible cures. They can direct people to research, resources, and services. Many groups also have experts who serve as medical advisors. Visit their website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.
Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.
These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.
Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.
