Rare Rheumatology News

Disease Profile


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



Polymicrogyria is a condition characterized by abnormal development of the brain before birth. Specifically, the surface of the brain develops too many folds which are unusually small. The signs and symptoms associated with the condition vary based on how much of the brain and which areas of the brain are affected; however, affected people may experience recurrent seizures (epilepsy); delayed development; crossed eyes; problems with speech and swallowing; and muscle weakness or paralysis. Bilateral forms (affecting both sides of the brain) tend to cause more severe neurological problems. Polymicrogyria can result from both genetic and environmental causes. It may occur as an isolated finding or as part of a syndrome. Treatment is based on the signs and symptoms present in each person.[1][2]


A wide variety of symptoms may be observed in people with polymicrogyria, depending on the areas of the brain implicated and whether or not it is part of a larger syndrome. Signs and symptoms may include:[3][4]

  • Developmental delay
  • Crossed eyes
  • Epilepsy
  • Paralysis of the face, throat, and tongue
  • Difficulty with speech and swallowing
  • Drooling


The diagnosis of polymicrogyria is made by imaging brain structures using MRI. Typical findings include areas of the cerebral cortex with a complex set of small gyri that appear fused to each other and separated by shallow sulci. These findings may be isolated to one side of the brain (unilateral) or may involve both sides of the brain (bilateral).[3][4]


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

      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.
      • 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 Polymicrogyria. Click on the link to view a sample search on this topic.


        1. Polymicrogyria. Genetics Home Reference. June 2009; https://ghr.nlm.nih.gov/condition/polymicrogyria. Accessed 6/15/2015.
        2. Chang B, Walsh CA, Apse K, Bodell A. Polymicrogyria Overview. GeneReviews. August 6, 2007; https://www.ncbi.nlm.nih.gov/books/NBK1329/. Accessed 6/15/2015.
        3. Golden JA, Bonnemann CG. Developmental Structural Disorders. In: Goetz CG. Textbook of Clinical Neurology. Philadelphia, PA: Saunders; 2007;
        4. polymicrogyria. Genetics Home Reference. June 2009; https://ghr.nlm.nih.gov/condition/polymicrogyria. Accessed 5/25/2016.

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