This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.
|Medical Terms||Other Names||
|80%-99% of people have these symptoms|
Mental retardation, progressive
Progressive mental retardation[ more ]
|Intellectual disability, severe||
Early and severe mental retardation
Mental retardation, severe
Severe mental retardation[ more ]
|30%-79% of people have these symptoms|
|Abnormality of extrapyramidal motor function||0002071|
|Aplasia/Hypoplasia of the cerebellum||
Absent/underdeveloped cerebellum[ more ]
Psychiatric disturbances[ more ]
Increased size of skull
Large head circumference[ more ]
Low or weak muscle tone
Tumor of the nervous system
|5%-29% of people have these symptoms|
|Percent of people who have these symptoms is not available through HPO|
|Abnormal pyramidal sign||0007256|
Degeneration of cerebellum
Loss of developmental milestones
Mental deterioration in childhood[ more ]
|Global brain atrophy||
Generalized brain degeneration
Hearing defect[ more ]
Onset in first year of life
Onset in infancy[ more ]
|Morphological abnormality of the pyramidal tract||0002062|
Involuntary, rapid, rhythmic eye movements
|Severe demyelination of the white matter||0007258|
Squint eyes[ more ]
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.
If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.
If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.
You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.
Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.
Conditions with similar signs and symptoms from Orphanet
Urinary organic acid screening does not allow differentiation between L-2-hydroxygluratic acid and D-2-hydroxyglurac acid. Therefore, this differentiation has to be performed subsequently by a specialized laboratory.
Visit the Orphanet disease page for more information.
Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.
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.