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Disease Profile

Malignant migrating partial seizures of infancy

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.

<1 / 1 000 000

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)

Migrating partial epilepsy of infancy; Migrating partial seizures of infancy; MMPEI;


Congenital and Genetic Diseases; Nervous System Diseases


Malignant migrating partial seizures of infancy (MMPSI) is a severe form of epilepsy, a condition characterized by recurrent seizures. In MMPSI, specifically, partial seizures generally begin shortly after birth and are often not responsive to treatment. Although the seizures may occur relatively infrequently in the beginning, within a few months the frequency increases drastically with some affected people experiencing clusters of 5 to 30 seizures several times per day. Signs and symptoms associated with these episodes vary based on which part of the brain is affected during a given seizure. Although the seizures associated with MMPSI do eventually become less frequent, the long-term consequences of the condition may include profound developmental delay, microcephaly (unusually small head size), intellectual disability and a shortened lifespan (many do not survive past infancy or early childhood).[1][2][3] Although the underlying cause of MMPSI is not fully understood, de novo mutations in certain genes have been identified in several affected people and are thought to be involved in the development of the condition. Even when a genetic cause is identified, most cases of MMPSI occur sporadically in people with no family history of the condition.[1] Treatment is generally focused on minimizing recurrent seizures. Unfortunately, the seizures associated with MMPSI are usually not well-controlled with medications that are typically prescribed to treat epilepsy.[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:
5%-29% of people have these symptoms
Poor eye contact
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
Cerebral cortical atrophy
Decrease in size of the outer layer of the brain due to loss of brain cells
Delayed myelination
Developmental regression
Loss of developmental milestones
Mental deterioration in childhood

[ more ]

Epileptic encephalopathy
Generalized hypotonia
Decreased muscle tone
Low muscle tone

[ more ]

Hypoplasia of the corpus callosum
Underdevelopment of part of brain called corpus callosum
Abnormally small skull
Decreased circumference of cranium
Decreased size of skull
Reduced head circumference
Small head circumference

[ more ]

Neuronal loss in central nervous system
Loss of brain cells
Worsens with time
Involuntary muscle stiffness, contraction, or spasm
Status epilepticus
Repeated seizures without recovery between them
Paralysis of all four limbs


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.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.


    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

      • Epilepsy Action offers an information page on Malignant migrating partial seizures of infancy. Please click on the link to access this resource.
      • Genetics Home Reference (GHR) contains information on Malignant migrating partial seizures of infancy. This website is maintained by the National Library of Medicine.

        In-Depth Information

        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
        • 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 Malignant migrating partial seizures of infancy. Click on the link to view a sample search on this topic.


          1. Malignant migrating partial seizures of infancy. Genetics Home Reference. March 2014; https://ghr.nlm.nih.gov/condition/malignant-migrating-partial-seizures-of-infancy.
          2. Ishii A, Shioda M, Okumura A, Kidokoro H, Sakauchi M, Shimada S, Shimizu T, Osawa M, Hirose S, Yamamoto T. A recurrent KCNT1 mutation in two sporadic cases with malignant migrating partial seizures in infancy. Gene. December 2013; 531(2):467-471.
          3. Migrating partial epilepsy in infancy. Epilepsy Action. October 2013; https://www.epilepsy.org.uk/info/syndromes/migrating-partial-epilepsy-in-infancy.