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| == '''Alternate names''' ==
| | #REDIRECT [[Patau syndrome]] |
| Patau syndrome; Chromosome 13, trisomy 13 complete; Complete trisomy 13 syndrome; D trisomy syndrome (formerly) | |
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| == '''Definition''' ==
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| Trisomy 13 is a type of chromosome disorder characterized by having '''3 copies of chromosome 13''' in cells of the body, instead of the usual 2 copies. In some affected people, only a portion of cells contains the extra chromosome 13 (called mosaic trisomy 13), whereas other cells contain the normal chromosome pair.
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| Trisomy 13, also called Patau syndrome, is a chromosomal condition associated with severe [[intellectual disability]] and physical abnormalities in many parts of the body.
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| [[File:Trisomy13.jpg|thumb]]
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| [[File:HandTrisomy13.png|thumb]]
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| == '''Epidemiology''' ==
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| Trisomy 13 occurs in about 1 in 16,000 newborns. Although women of any age can have a child with trisomy 13, the chance of having a child with this condition increases as a woman gets older.
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| == '''Cause''' ==
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| * Most cases of trisomy 13 result from having '''three copies of chromosome 13''' in each cell in the body instead of the usual two copies.
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| * The extra genetic material disrupts the normal course of development, causing the characteristic features of trisomy 13.
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| * 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.
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| * Affected people have two normal copies of chromosome 13, plus an extra copy of chromosome 13 attached to another chromosome.
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| * In rare cases, only part of chromosome 13 is present in three copies.
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| * The physical signs and symptoms in these cases may be different than those found in full trisomy 13.
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| * A small percentage of people with trisomy 13 have '''an extra copy of chromosome 13 in only some of the body's cells'''.
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| * In these people, the condition is called '''mosaic trisomy 13'''.
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| * The severity of mosaic trisomy 13 depends on the type and number of cells that have the extra chromosome.
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| * The physical features of mosaic trisomy 13 are often milder than those of full trisomy 13.
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| == '''Inheritance''' ==
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| * Most cases of trisomy 13 are not inherited and result from random events during the formation of eggs and sperm in healthy parents.
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| * An error in cell division called [[nondisjunction]] results in a reproductive cell with an abnormal number of [[chromosome]]s.
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| * For example, an egg or sperm cell may gain an extra copy of chromosome 13.
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| * If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra chromosome 13 in each cell of the body.
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| '''Translocation trisomy 13''' can be '''inherited'''.
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| * An unaffected person can carry a rearrangement of genetic material between chromosome 13 and another chromosome.
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| * These rearrangements are called balanced [[translocations]] because there is no extra material from chromosome 13.
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| * A person with a balanced translocation involving chromosome 13 has an increased chance of passing extra material from chromosome 13 to their children.
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| == '''Signs and symptoms''' ==
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| * Trisomy 13 is associated with severe [[intellectual disability]] and physical abnormalities in many parts of the body.
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| * People with this condition often have congenital 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]]).
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| * 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]]).
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| Other features or trisomy 13 may include:
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| * Clenched hands (with outer fingers on top of the inner fingers)
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| * Close-set eyes
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| * [[Hernia]]s: umbilical hernia, inguinal hernia
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| * A hole, split, or cleft in the iris of the eye ([[coloboma]])
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| * Low-set ears
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| * Scalp defects such as missing skin
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| * [[Seizures]]
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| * Single palmar crease
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| * Skeletal (limb) abnormalities
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| * Small head ([[microcephaly]])
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| * Small lower jaw ([[micrognathia]])
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| * Undescended testicle ([[cryptorchidism]])
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| == '''Diagnosis''' ==
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| * While most cases of trisomy 13 occur randomly, a few cases are due to the presence of a translocation involving chromosome 13 in a parent.
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| * Parents who are at risk to have a translocation due to their family history can have a blood test called a [[karyotype]], which can determine if a [[translocation]] is present.
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| * Prenatal testing or screening (such as maternal blood screening, fetal [[ultrasound]], [[chorionic villus sampling]], or [[amniocentesis]]) is also available to determine if a current pregnancy is at risk for, or is affected by, trisomy 13 or other chromosome disorders.
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| * People with a family history of trisomy 13 who are interested in learning about genetic screening or testing for themselves or family members are encouraged speak with a genetic counselor or other genetics professional.
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| == '''Treatment''' ==
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| * Treatment for trisomy 13 depends on the affected person's signs and symptoms, and is generally symptomatic and supportive.
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| * Surgeries are generally withheld for the first few months of life because of the high mortality rate associated with trisomy 13.
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| * 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.
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| == '''Prognosis''' ==
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| Trisomy 13 involves multiple abnormalities, many of which are life-threatening.
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| More than 80% of children with trisomy 13 do not survive past the first month of life. For those that do survive, complications are common and may include:
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| * Breathing difficulty or lack of breathing (apnea)
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| * Deafness
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| * Feeding problems
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| * Heart failure
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| * Seizures
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| * Vision problems
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| * People with trisomy 13 who survive infancy have severe intellectual disability and developmental delays, and are at increased risk for cancers.
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| {{Chromosomal abnormalities}}
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| [[Category:Autosomal trisomies]] | | [[Category:Autosomal trisomies]] |
| [[Category:Syndromes with microcephaly]]
| | {{Redirect category shell|1= |
| [[Category:Syndromes with cleft lip and/or palate]]
| | {{R from alternative name}} |
| [[Category:Syndromes affecting the nervous system]]
| | }} |
| [[Category:Syndromes with dysmelia]]
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| [[Category:Syndromes affecting the heart]]
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| {{rarediseases}} | |
| {{stub}}
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