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Disease Profile

Bilateral frontal polymicrogyria

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable



Congenital and Genetic Diseases; Nervous System Diseases


Bilateral frontal polymicrogyria is one of the rarest subtypes of polymicrogyria. It is a symmetric and bilateral form (in both brain hemispheres) that only involves the frontal lobes without including the area located behind the Sylvius fissure or the area located behind the Rolando sulcus. Some researchers classify the condition into two different forms: bilateral frontal polymicrogyria and the bilateral frontoparietal. Signs and symptoms included delayed motor and language milestones; spastic (stiffness) hemiparesis (weakness in one side of the body) or quadriparesis (weakness in all four limbs of the body); and mild to moderate intellectual disability. Seizures may also be present. The frontoparietal form is caused by changes (mutations) in the GPR56 gene but the cause for the frontal form of polymicrogyira is still not known. Treatment is based on the signs and symptoms present in each person.[1][2][3]


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
Learn More:
80%-99% of people have these symptoms
Delayed speech and language development
Deficiency of speech development
Delayed language development
Delayed speech
Delayed speech acquisition
Delayed speech development
Impaired speech and language development
Impaired speech development
Language delay
Language delayed
Language development deficit
Late-onset speech development
Poor language development
Speech and language delay
Speech and language difficulties
Speech delay

[ more ]

Global developmental delay
30%-79% of people have these symptoms
Intellectual disability, mild
Mental retardation, borderline-mild
Mild and nonprogressive mental retardation
Mild mental retardation

[ more ]

Spastic tetraparesis
5%-29% of people have these symptoms
EEG abnormality
Functional motor deficit
Weakness of one side of body
Hyperactive deep tendon reflexes


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.

Organizations Supporting this Disease

    Learn more

    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.

    Where to Start

    • Genetics Home Reference (GHR) contains information on Bilateral frontal polymicrogyria. This website is maintained by the National Library of Medicine.

      In-Depth Information

      • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
      • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
      • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
      • PubMed is a searchable database of medical literature and lists journal articles that discuss Bilateral frontal polymicrogyria. Click on the link to view a sample search on this topic.


        1. Chang B, Walsh CA, Alpse K & Bodel A. Polymicrogyria Overview. Gene Review. August, 2007; https://www.ncbi.nlm.nih.gov/books/NBK1329/. Accessed 10/2/2015.
        2. Leventer R.J & cols. Clinical and imaging heterogeneity of polynicrogyria: a study of 328 patients. Brain. May, 2010; 133(5):1415-1427. https://brain.oxfordjournals.org/content/brain/early/2010/04/19/brain.awq078.full.pdf. Accessed 10/2/2015.
        3. Jansen A. & Andermann E. Genetics of the polymicrogyria syndromes. J Med Genet. 2005; 42:369–378. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1736054/pdf/v042p00369.pdf. Accessed 10/2/2015.