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Trisomy 13


Other Names for this Disease

  • Chromosome 13, trisomy 13 complete
  • Complete trisomy 13 syndrome
  • D trisomy syndrome (formerly)
  • Patau syndrome
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Overview

What is trisomy 13?

What are the signs and symptoms of trisomy 13?

What causes trisomy 13?

Is trisomy 13 inherited?

How might trisomy 13 be treated?

What is the long-term outlook for people with trisomy 13?

What is trisomy 13?

Trisomy 13, also called Patau syndrome, is a genetic disorder in which all or a portion of chromosome 13 appears three times (a trisomy) rather than twice in cells of the body. In some affected people, only a portion of cells may contain the extra chromosome 13 (called mosaic trisomy 13), whereas other cells contain the normal chromosomal pair.[1][2][3] Trisomy 13 causes severe intellectual disability and many physical abnormalities, such as heart defects; brain or spinal cord abnormalities; very small or poorly developed eyes (microphthalmia); extra fingers or toes; cleft lip with or without cleft palate; and weak muscle tone (hypotonia). Most cases are not inherited and result from random errors during the formation of eggs or sperm in healthy parents.[2] Due to various life-threatening medical problems, many infants with trisomy 13 do not survive past the first days or weeks of life.[2]
Last updated: 1/20/2015

What are the signs and symptoms of trisomy 13?

Trisomy 13 is associated with severe intellectual disability and physical abnormalities in many parts of the body. Individuals with this condition often have heart defects, brain or spinal cord abnormalities, very small or poorly developed eyes (microphthalmia), extra fingers and/or toes (polydactyly), cleft lip or palate, and decreased muscle tone (hypotonia).[2] Many infants with trisomy 13 fail to grow and gain weight at the expected rate (failure to thrive), have severe feeding difficulties, and episodes in which there is temporary cessation of spontaneous breathing (apnea).[1]

Other features or trisomy 13 may include:[3]
Last updated: 1/20/2015

What causes trisomy 13?

Most cases of trisomy 13 are not inherited and are caused by random events during the formation of eggs and sperm in healthy parents (prior to conception). The condition typically results from having three copies of chromosome 13 in each cell in the body, instead of the usual two copies. This is referred to as complete, or full, trisomy 13. The extra genetic material disrupts the normal course of development, causing the characteristic features of trisomy 13.

Trisomy 13 can also occur when part of chromosome 13 becomes attached (translocated) to another chromosome during the formation of reproductive cells (eggs and sperm) or very early in fetal development. This is referred to as translocation trisomy 13. Individuals with this type have two normal copies of chromosome 13, plus an extra copy of chromosome 13 attached to another chromosome.

In rare cases, only part of chromosome 13 is present in three copies in each cell; this is called partial trisomy 13.  In other rare cases, a person has an extra copy of chromosome 13 in only some of the body's cells; this is called mosaic trisomy 13. The severity of mosaic trisomy 13 depends on the type and number of cells that have the extra chromosome.[4]
Last updated: 1/20/2015

Is trisomy 13 inherited?

Most cases of trisomy 13 are not inherited and result from random events during the formation of eggs and sperm in healthy parents. An error in cell division called nondisjunction results in an egg or sperm cell with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of chromosome 13. If one of these contributes to the genetic makeup of a child, the child will have an extra chromosome 13 in each cell of the body.[4] For a woman who has never had a pregnancy or child with a trisomy, the risk to have a pregnancy with a chromosome abnormality would typically be her age-related risk; the risk increases with maternal age. For a woman who has had an affected pregnancy or child in the past, the risk is generally quoted as about 1% or the maternal age-related risk - whichever is higher at the time of pregnancy.

On the other hand, translocation trisomy 13 can be inherited. An unaffected person can carry a rearrangement of genetic material between chromosome 13 and another chromosome. These rearrangements are called balanced translocations because there is no extra or missing material from chromosome 13. A person with a balanced translocation involving chromosome 13 has an increased chance of passing extra material from chromosome 13 to their children.[4] Individuals interested in learning about their personal risk to have a child with a chromosome abnormality should speak with their health care provider or a genetics professional.
Last updated: 1/20/2015

How might trisomy 13 be treated?

Treatment for trisomy 13 depends on the affected individual's condition and is generally symptomatic and supportive.[3] Surgical interventions are generally withheld for the first few months of life because of the high mortality rates of babies with trisomy 13. Parents and medical personnel must carefully weigh decisions about extraordinary life-prolonging measures against the severity of the neurological and physical defects that are present and the likelihood of post-surgical recovery or prolonged survival.[5]
Last updated: 1/20/2015

What is the long-term outlook for people with trisomy 13?

Trisomy 13 involves multiple abnormalities, many of which are life-threatening. More than 80% of children with this condition do not survive past the first month of life. For those that do survive, complications are common and may include:[3]
  • Breathing difficulty or lack of breathing (apnea)
  • Deafness
  • Feeding problems
  • Heart failure
  • Seizures
  • Vision problems

People with trisomy 13 who survive infancy have severe intellectual disability and developmental delays, and are at increased risk for cancers.[5]

Last updated: 1/20/2015

References
  1. Trisomy 13 Syndrome. National Organization for Rare Disorders (NORD). 2007; http://www.rarediseases.org/search/rdbdetail_abstract.html?disname=Trisomy%2013%20Syndrome. Accessed 10/13/2009.
  2. Trisomy 13. Genetics Home Reference (GHR). 2009; http://ghr.nlm.nih.gov/condition=trisomy13. Accessed 10/13/2009.
  3. Chambers D. Trisomy 13. MedlinePlus. 2009; http://www.nlm.nih.gov/medlineplus/ency/article/001660.htm. Accessed 10/13/2009.
  4. Trisomy 13. Genetics Home Reference. January 2009; http://ghr.nlm.nih.gov/condition/trisomy-13. Accessed 2/2/2011.
  5. Best RG, Stallworth J. Patau Syndrome. eMedicine. 2007; http://emedicine.medscape.com/article/947706-overview. Accessed 10/13/2009.


Other Names for this Disease
  • Chromosome 13, trisomy 13 complete
  • Complete trisomy 13 syndrome
  • D trisomy syndrome (formerly)
  • Patau syndrome
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.