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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


Other names (AKA)

Macrogyria; Broad gyri of cerebrum; Large gyri of cerebrum


Congenital and Genetic Diseases


Pachygyria is a developmental condition due to abnormal migration of nerve cells (neurons) in the developing brain and nervous system.[1] With pachygyria, there are few gyri (the ridges between the wrinkles in the brain), and they are usually broad and flat. The condition is also known as "incomplete lissencephaly."[2][3] Pachygyria may occur alone (isolated) or as part of various underlying syndromes. Symptoms vary among affected people and may include moderate to severe developmental delay, seizures, poor muscle tone and control, feeding or swallowing difficulties, and small head size (microcephaly).[1] In most cases it is not inherited, but various inheritance patterns have been reported.[1][4] Treatment is symptomatic and supportive.[1][2]


Signs and symptoms of pachygyria vary among affected people and can depend on the extent of the abnormality. They often include poor muscle tone and motor function; seizures; developmental delays; intellectual disability; failure to grow and thrive; difficulties with feeding or swallowing; swelling in the extremities; and small head size (microcephaly). Most infants appear physically normal, but some conditions associated with pachygyria cause distinctive facial or skull characteristics.[1]

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
Bilateral tonic-clonic seizure
Grand mal seizures
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
Intellectual disability, severe
Early and severe mental retardation
Mental retardation, severe
Severe mental retardation

[ more ]

Muscular hypotonia
Low or weak muscle tone
Reduced tendon reflexes
Urinary incontinence
Loss of bladder control
30%-79% of people have these symptoms
Inward turning cross eyed
Wide-set eyes
Widely spaced eyes

[ more ]

Premature birth
Premature delivery of affected infants
Preterm delivery

[ more ]

Corners of eye widely separated
Percent of people who have these symptoms is not available through HPO
Abnormality of the skeletal system
Skeletal abnormalities
Skeletal anomalies

[ more ]

Arachnoid cyst
Fluid-filled sac located in membrane surrounding brain or spinal cord
Atypical absence seizure
Autosomal recessive inheritance
Intellectual disability
Mental deficiency
Mental retardation
Mental retardation, nonspecific

[ more ]

Intellectual disability, moderate
IQ between 34 and 49
Fewer and broader ridges in brain
Profound static encephalopathy


Pachygyria, also called "incomplete lissencephaly," may be caused by various non-genetic (environmental) and genetic factors that play a role in impairing the development of the outer region of the brain (the cerebral cortex).[5] The cerebral cortex is responsible for conscious movement and thought, and should have deep convolutions (gyri) and grooves (sulci), which are formed by "infolding" of the cerebral cortex. During normal embryonic growth, immature cells that later develop into specialized nerve cells (neurons) normally migrate to the brain's surface, making several layers of cells. When this process is impaired, the cells don't migrate to their locations, resulting in too few cell layers and absence (agyria) or incomplete development (pachygyria) of gyri.[5]

Environmental factors that contribute to the condition may include intrauterine infection during pregnancy (such as a virus), and insufficient flow of oxygenated blood to the brain (ischemia) during fetal development.[5]

More than 25 syndromes due to abnormal migration of neurons have been reported; in some of these cases, the genetic cause and pattern of inheritance depends on that of the specific syndrome.[1][4]

Mutations in several genes have been identified in people with abnormalities of cortical development, including the KIF5C, KIF2A, DYNC1H1, WDR62, and TUBG1 genes.[6] Studies have also found that isolated lissencephaly may result from mutations in the LIS1 and XLIS (also called DCX) genes.[5]

People interested in learning about the cause of pachygyria in themselves or family members should speak with their health care provider or a a genetics professional.


Because the symptoms of the condition vary from person to person, treatment is symptomatic, and may include antiseizure medication, such as Trileptal, and special or supplemental education consisting of physical, occupational, and speech therapies.[1][2]?xml:namespace prefix = o /


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.

Social Networking Websites

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


  1. NINDS Neuronal Migration Disorders Information Page. National Institute of Neurological Disorders and Stroke (NINDS) Web site. https://www.ninds.nih.gov/Disorders/All-Disorders/Neuronal-Migration-Disorders-Information-Page. Accessed 9/30/2017.
  2. Grainger & Allison's Diagnostic Radiology: A Textbook of Medical Imaging, 4th ed.. 2001;
  3. Roy U, Pandit A, Das U, Panwar A. “Reverse Tigroid” Pattern in Pachygyria: A Novel Finding. J Clin Imaging Sci. 2016; 56:15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4863413/.
  4. Straussberg R, Gross S, Amir J, Gadoth N. A new autosomal recessive syndrome of pachygyria. Clin Genet. 1996; https://www.ncbi.nlm.nih.gov/pubmed/9147882.
  5. LISSENCEPHALY. NORD. September 6, 2012; https://www.rarediseases.org/rare-disease-information/rare-diseases/byID/454/viewAbstract. Accessed 2/20/2014.
  6. Poirier K et. al. Mutations in TUBG1, DYNC1H1, KIF5C and KIF2A cause malformations of cortical development and microcephaly. Nat Genet. June, 2013; 45(6):639-647. Accessed 2/20/2014.

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