Rare Pulmonology News

Disease Profile

Anencephaly

Prevalence
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.
1-9 / 1 000 000

331 - 2,979

US Estimated

1-9 / 1 000 000

514 - 4,622

Europe Estimated

Age of onset

Infancy

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ICD-10

Q00.0

Inheritance

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

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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

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X-linked
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.

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

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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.

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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.

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Not applicable

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Other names (AKA)

Absence of a large part of the brain and the skull

Categories

Congenital and Genetic Diseases; Nervous System Diseases

Summary

Anencephaly is a type of neural tube defect characterized by abnormal development of the brain and the bones of the skull. The neural tube is a narrow channel that normally folds and closes between the 3rd and 4th weeks of pregnancy, forming the brain and spinal cord of the embryo. Anencephaly occurs when the 'cephalic' or head end of the neural tube fails to close, causing the absence of a major portion of the brain, skull, and scalp. Infants with this disorder are born without a forebrain (the front part of the brain) and a cerebrum (the thinking and coordinating part of the brain). The remaining brain tissue is often exposed (not covered by bone or skin). Affected babies are usually blind, deaf, unconscious, and unable to feel pain. Almost all babies with anencephaly die before birth, although some may survive a few hours or a few days after birth. Anencephaly is likely caused by an interaction between genetic and environmental factors, many of which remain unknown.[1][2][3]

Symptoms

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:
HPO ID
80%-99% of people have these symptoms
Anencephaly
0002323
Primary adrenal insufficiency
0008207
Percent of people who have these symptoms is not available through HPO
Autosomal recessive inheritance
0000007
Congenital onset
Symptoms present at birth
0003577
Spina bifida
0002414

Cause

The underlying cause of anencephaly is not fully understood. Like other forms of neural tube defects (NTDs), anencephaly is likely caused by the interaction of multiple genes and environmental factors, many of which remain unknown.[3]

Variations in many genes may influence the risk of developing anencephaly. The best-studied gene thus far is the MTHFR gene, which gives the body instructions to make a protein used to process the vitamin folate (also called vitamin B9). A deficiency of folate is a known risk factor for NTDs. Other genes involved in folate processing, and the development of the neural tube, may also affect the risk.

Researchers have also looked at environmental factors that could contribute to the risk of anencephaly. Folate appears to play a significant role, and studies have shown that taking folic acid (a form of folate), before getting pregnant and very early in pregnancy, significantly reduces the risk to have a baby with a NTD. Other possible maternal risk factors for anencephaly include diabetes mellitus; obesity; exposure to high heat (such as a fever or use of a hot tub or sauna) in early pregnancy; and the use of certain antiseizure medications during pregnancy.[3]

Organizations

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

    Organizations Providing General Support

      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

      • You can obtain information on this topic from the Centers for Disease Control and Prevention (CDC). The CDC is recognized as the lead federal agency for developing and applying disease prevention and control, environmental health, and health promotion and education activities designed to improve the health of the people of the United States.
      • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
      • Genetics Home Reference (GHR) contains information on Anencephaly. This website is maintained by the National Library of Medicine.
      • The National Institute of Neurological Disorders and Stroke (NINDS) collects and disseminates research information related to neurological disorders. Click on the link to view information on this topic.
      • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

        In-Depth Information

        • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
        • 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.
        • 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 Anencephaly. Click on the link to view a sample search on this topic.

          References

          1. NINDS Anencephaly Information Page. National Institute of Neurological Disorders and Stroke (NINDS). June 30, 2015; https://www.ninds.nih.gov/disorders/anencephaly/anencephaly.htm.
          2. Anencephaly. Orphanet. 2006; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=1048. Accessed 11/28/2011.
          3. Anencephaly. Genetics Home Reference. November, 2014; https://ghr.nlm.nih.gov/condition/anencephaly.
          4. Robert G Best. Anencephaly. Medscape Reference. November, 2013; https://emedicine.medscape.com/article/1181570-overview.
          5. Diana W. Bianchi, Timothy M. Crombleholme, Mary E. D'Alton, Fergal D. Malone. Management of fetal conditions diagnosed by sonography. Fetology: Diagnosis and Management of the Fetal Patient, Second Edition. McGraw-Hill Companies; 2010; 77-82.

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