Chromosomen zitten in al onze lichaamscellen en bevatten onze erfelijke eigenschappen. Mensen met het downsyndroom hebben een lichte tot ernstige verstandelijke handicap en een aantal uiterlijke kenmerken. Kinderen met het downsyndroom ontwikkelen zich trager, zowel lichamelijk als verstandelijk. Een groot deel van de kinderen met het downsyndroom overlijdt tijdens de zwangerschap.
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Each cell normally contains 23 pairs of chromosomes , which carry the genes you inherit from your parents. Their growth in the womb is often restricted, resulting in a low birth weight, and 8 out of 10 will be born with severe heart defects. The brain often does not divide into 2 halves. This is known as holoprosencephaly. They occur randomly during conception, when the sperm and egg combine and the foetus starts to develop.
In many cases, the baby dies before reaching full term miscarriage or is dead at birth stillbirth. This is sometimes known as trisomy 13 or simple trisomy This is called a chromosomal translocation. Genetic Alliance UK has more information about chromosome disorders. In a further 1 in 20 cases, only some cells have the extra copy of chromosome This is known as trisomy 13 mosaicism. Occasionally, only part of 1 chromosome 13 is extra partial trisomy The symptoms and features of both mosaicism and partial trisomy tend to be less severe than in simple trisomy 13, resulting in more babies living longer.
The test assesses your chances of having a baby with these syndromes. These are invasive tests to remove a sample of tissue or fluid so it can be tested for the presence of the extra copy of chromosome This is known as non-invasive prenatal testing and is only available privately. As a result of the severe health problems a newborn baby with the syndrome will have, doctors usually focus on minimising discomfort and ensuring the baby is able to feed.
Genetic testing is carried out to help parents plan for future pregnancies, rather than as part of the decision making process for the current pregnancy. The test results will allow a more accurate assessment to be made of the likelihood of the syndrome affecting future pregnancies. Other family members may also be affected and should be tested. This helps scientists look for better ways to prevent and treat this condition.
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Síndrome de Patau
Causes[ edit ] Patau syndrome is the result of trisomy 13, meaning each cell in the body has three copies of chromosome 13 instead of the usual two. Patau syndrome can also occur when part of chromosome 13 becomes attached to another chromosome translocated before or at conception in a Robertsonian translocation. Affected people have two copies of chromosome 13, plus extra material from chromosome 13 attached to another chromosome. With a translocation, the person has a partial trisomy for chromosome 13 and often the physical signs of the syndrome differ from the typical Patau syndrome. Most cases of Patau syndrome are not inherited, but occur as random events during the formation of reproductive cells eggs and sperm. An error in cell division called non-disjunction can result in reproductive cells with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of the chromosome.
Trisomie 13 (Pätau-Syndrom ): Symptome