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Trisomy 18 (Edwards syndrome)TTrisomy 18 (Edwards syndrome)Trisomy 18 (Edwards syndrome)EnglishGeneticsChild (0-12 years)BodyNAConditions and diseasesCaregivers Adult (19+)NA2016-07-19T04:00:00ZDavid Chitayat, MD, FABMG, FACMG, FCCMG, FRCPC11.000000000000046.0000000000000902.000000000000Health (A-Z) - ConditionsHealth A-Z<p>Information for parents about trisomy 18, a rare genetic condition that causes developmental delay and affects many different organ systems.</p><h2>What is a trisomy?</h2><p>The term trisomy (say: TRY-so-mee) means that there are three <a href="/htbw?module=genetics">chromosomes</a>, rather than the usual pair of chromosomes. For example, a baby with <a href="/Article?contentid=9&language=English">Down syndrome</a> usually has three copies of chromosome 21, rather than the usual pair. The condition is thus called "trisomy 21."</p><h2>What is trisomy 18?<br></h2><p>Trisomy 18 is a rare chromosome abnormality that affects approximately one in every 6,000 to 8,000 live births. These children have developmental delay, as well as birth defects and health problems involving nearly every organ system in the body.</p><p>Trisomy 18 is also called Edwards syndrome, after the physician who first described the disorder.<br></p> <figure class="asset-c-80"> <span class="asset-image-title">Edwards syndrome </span><span class="asset-image-title"></span><span class="asset-image-title"></span><span class="asset-image-title">karyotype</span><img src="https://assets.aboutkidshealth.ca/akhassets/Trisomy_18_Edwards_syndrome_MED_ILL_EN.jpg" alt="The pairs of chromosomes in a female with an extra copy of chromosome 18" /><figcaption class="asset-image-caption">People</figcaption><figcaption class="asset-image-caption"></figcaption><figcaption class="asset-image-caption"></figcaption><figcaption class="asset-image-caption"> with Edwards syndrome have an extra copy of chromosome 18.</figcaption> </figure><h2>Key points</h2> <ul> <li>Trisomy 18 is a rare condition caused by an extra copy of chromosome 18.</li> <li>Children with trisomy 18 have severe developmental delay, as well as severe birth defects and health problems involving nearly every organ system in the body. </li> <li>It is difficult to predict the life expectancy of a baby with trisomy 18.</li> <li>Parents of a baby with trisomy 18 are encouraged to seek genetic counselling.</li> </ul><h2>Signs and symptoms of trisomy 18</h2><p>Babies with trisomy 18 have low birth weight, have a weak cry and startle to sound. They have problems feeding and fail to thrive. They have a small head size, with a prominent back of the head (occiput). Their ears are usually low-set and the openings of their eyes, their nose and their mouth are small. Their sternum (breastbone) is typically short. Almost all babies with trisomy 18 have <a href="/Article?contentid=1600&language=English">heart defects</a>. They have clenched fists from before birth and extending the fingers fully is difficult. Their elbows and knee joints are in a bent position rather than relaxed. They typically have club feet and their feet have been described as a “rocker bottom” due to their shape. Babies with trisomy 18 may also have <a href="/Article?contentid=371&language=English">spina bifida</a>, <a href="/Article?contentid=380&language=English">cleft lip and palate</a>, eye problems and hearing loss. Some develop <a href="/Article?contentid=2060&language=English">seizures</a> in the first year of life, <a href="/htbw?module=kidney-child">kidney</a> problems and <a href="/article?contentid=2006&language=English">scoliosis</a> (curvature of the spine).<br></p><p>Feeding difficulties, heart problems and an increased susceptibility to infection are factors which contribute to the death of children with trisomy 18.</p><h2>What causes trisomy 18?<br></h2><p>Usually each egg and sperm cell contains 23 chromosomes. At the time of <a href="/Article?contentid=310&language=English">fertilization</a>, the sperm and egg unite and create a cell with 23 chromosome pairs, or 46 chromosomes. In this manner, a child receives exactly half of their genetic material from each parent. </p><p>Sometimes, an error occurs when the egg or sperm cell is forming, causing it to have an extra chromosome. When this cell contributes the extra chromosome 18 to the embryo, trisomy 18 results. The extra chromosome 18 can come from either the mother’s egg cell or the father’s sperm cell. The abnormalities seen in babies with trisomy 18 result from having this extra chromosome 18 in each of the body’s cells.</p><p>Rarely, mosaic trisomy 18 may occur when the error in cell division occurs after fertilization. These babies have some cells with an extra chromosome 18 and others with the normal number. These babies usually have milder forms of trisomy 18. </p><h2>Diagnosis of trisomy 18</h2><p>Babies with trisomy 18 have a unique group of characteristics and can be diagnosed by physical examination. To confirm the diagnosis, a small blood sample can be taken and the chromosomes can be analyzed to determine the presence of an extra chromosome 18.</p><p>Chromosomal abnormalities can also be diagnosed before birth by analyzing cells in the amniotic fluid obtained by <a href="/Article?contentid=342&language=English">amniocentesis</a>, or from the placenta, obtained by <a href="/Article?contentid=342&language=English">chorionic villus sampling</a> (CVS) or from the fetal blood obtained by cordocentesis. Screening for trisomy 18 is also available through first trimester screening (FTS), integrated prenatal screening (IPS) or by non-invasive prenatal testing (NIPT). The diagnosis of trisomy 18 can also be suggested by detailed <a href="/Article?contentid=342&language=English">fetal ultrasound</a>; however, ultrasound is not 100% accurate, since not all abnormalities can be seen on ultrasound and the same abnormalities seen prenatally in trisomy 18 can also be seen in other conditions. In contrast, a <a href="/htbw?module=genetics">chromosome analysis</a>, whether performed on fetal/newborn blood sample, cells from the amniotic fluid or placental sample, is over 99.9% accurate.</p>
Trisomie 18 (syndrome d’Edwards)TTrisomie 18 (syndrome d’Edwards)Trisomy 18 (Edwards syndrome)FrenchGeneticsChild (0-12 years)BodyNAConditions and diseasesAdult (19+) CaregiversNA2016-07-19T04:00:00ZDavid Chitayat, MD, FABMG, FACMG, FCCMG, FRCPCHealth (A-Z) - ConditionsHealth A-Z<p>Renseignements pour les parents au sujet de la trisomie 18, un trouble génétique rare qui cause des retards de développement et touche différents systèmes organiques.</p><h2>Qu’est-ce qu’une trisomie?</h2><p>Le terme trisomie (prononcez : tri-zo-mi) signifie que trois chromosomes sont présents plutôt que la paire habituelle de <a href="/htbw?module=genetics">chromosomes</a>. Par exemple, un bébé atteint du <a href="/Article?contentid=9&language=French">syndrome de Down</a> présente généralement trois exemplaires du chromosome 21 au lieu de la paire habituelle. Le trouble est ainsi nommé « trisomie 21 ».</p><h2>Qu’est-ce que la trisomie 18?</h2><p>La trisomie 18 est une anomalie chromosomique rare qui affecte approximativement une naissance sur 5 000 à 10 000. Ces enfants présentent des retards de développement importants de même que des anomalies congénitales graves et des problèmes de santé touchant presque tous les systèmes organiques du corps.</p><p>La trisomie 18 est aussi nommée syndrome d’Edwards, d’après le médecin qui le premier a décrit ce trouble.</p> <figure class="asset-c-80"> <span class="asset-image-title">Caryotype du syndrome d’Edwards</span><img src="https://assets.aboutkidshealth.ca/akhassets/Trisomy_18_Edwards_syndrome_MED_ILL_EN.jpg" alt="Les paires de chromosomes d’une femelle avec une copie supplémentaire du chromosome 18" /><figcaption class="asset-image-caption">Les personnes atteintes du syndrome d’Edwards présentent un exemplaire excédentaire du chromosome 18.</figcaption> </figure><h2>À retenir</h2><ul><li>La trisomie 18 est un trouble rare causé par un exemplaire excédentaire du chromosome 18.</li><li>Ces enfants atteints de trisomie 18 présentent des retards de développement importants de même que des anomalies congénitales graves et des problèmes de santé touchant presque tous les systèmes organiques du corps.</li><li>Il est difficile de prédire l’espérance de vie d’un bébé atteint de trisomie 18.</li><li>On suggère aux parents d’un bébé atteint de trisomie 18 de demander une consultation génétique.</li></ul><h2>Symptômes de la trisomie 18</h2><p>Les bébés atteints de trisomie 18 présentent un faible poids de naissance, pleurent faiblement et sursautent au bruit. Ils éprouvent des problèmes à s’alimenter et n’arrivent pas à se développer. Leur tête est de petite taille, l’arrière étant proéminent (occiput). La position de leurs oreilles est habituellement basse et les ouvertures de leurs yeux, de leur nez et de leur bouche sont petites. Leur sternum est typiquement court. Presque tous les bébés atteints de trisomie 18 présentent des <a href="/Article?contentid=1600&language=French">malformations cardiaques</a>. Leurs poings sont serrés avant même la naissance et l’extension complète des doigts est difficile. Leurs articulations des coudes et des genoux restent en position courbée plutôt que relâchée. Ils présentent typiquement un pied bot et leurs pieds ont été décrits comme étant en « forme de piolet » en raison de leur malformation. Les bébés atteints de trisomie 18 peuvent aussi présenter un <a href="/Article?contentid=371&language=French">spina-bifida</a>, un <a href="/Article?contentid=380&language=French">bec-de-lièvre et une fente palatine</a>, des troubles oculaires et une perte d’audition. Certains développent des <a href="/Article?contentid=2060&language=French">convulsions</a> au cours de leur première année de vie, des troubles <a href="/htbw?module=kidney-child">rénaux</a> et une <a href="/article?contentid=2006&language=French">scoliose</a> (une courbature de la colonne).</p><p>Les difficultés d’alimentation, les troubles cardiaques et une sensibilité croissante aux infections sont des facteurs qui contribuent à la mort de ces enfants.</p><h2>Qu’est-ce qui cause la trisomie 18?</h2><p>Habituellement, chaque ovule et chaque spermatozoïde comprend 23 chromosomes. Au moment de la <a href="/Article?contentid=310&language=French">fécondation</a>, le spermatozoïde et l’ovule s’unissent et créent une cellule composée de 23 paires de chromosomes, soit 46 chromosomes. De cette façon, un enfant reçoit exactement la moitié de son matériel génétique de chacun de ses parents.</p><p>Parfois, une erreur se produit lors de la formation de l’ovule ou du spermatozoïde, entraînant la présence d’un chromosome excédentaire. Lorsque cette cellule donne un chromosome 18 excédentaire à l’embryon, il en résulte une trisomie 18. Le chromosome 18 excédentaire peut provenir de l’ovule de la mère ou du spermatozoïde du père. Les anomalies observées chez les bébés atteints de trisomie 18 sont le résultat de la présence de ce chromosome 18 excédentaire dans chacune des cellules du corps.</p><p>À l’occasion, le chromosome excédentaire 18 est attaché à un autre chromosome de l’ovule ou du spermatozoïde; on parle alors d’une translocation. Il s’agit de la seule forme de trisomie 18 pouvant être héréditaire dans une famille. Parfois, un parent peut être porteur d’un réarrangement « équilibré » où le chromosome 18 est attaché à un autre chromosome. Cependant, puisque le parent ne possède pas de matériel chromosomique excédentaire ou manquant, on dit qu’il présente une « translocation équilibrée » puisqu’il est normal et en santé.</p><p>En de rares occasions, une trisomie 18 mosaïque peut se produire quand l’erreur de division cellulaire survient après la fécondation. Certaines cellules de ces bébés possèdent un chromosome 18 excédentaire et d’autres ont le nombre habituel. Ces bébés présentent habituellement une forme atténuée de trisomie 18.</p><h2>Diagnostic de la trisomie 18</h2><p>Les bébés atteints de trisomie 18 possèdent un ensemble unique de caractéristiques qui peuvent être diagnostiquées par un examen physique. Afin de confirmer un diagnostic, un petit échantillon de sang peut être prélevé et les chromosomes peuvent être analysés pour déterminer la présence d’un chromosome 18 excédentaire.</p><p>Les anomalies chromosomiques peuvent être diagnostiquées avant la naissance en analysant les cellules contenues dans le liquide amniotique obtenues par <a href="/Article?contentid=342&language=French">amniocentèse</a> ou par le placenta au moyen du <a href="/Article?contentid=342&language=French">prélèvement de villosités choriales (PVC</a>). Le diagnostic de la trisomie 18 peut aussi être soupçonné par une <a href="/Article?contentid=342&language=French">échographie fœtale</a> détaillée; cependant, l’échographie n’est pas précise à 100 %, car ce ne sont pas toutes les anomalies qui peuvent être visibles à l’échographie. Par ailleurs, une <a href="/htbw?module=genetics">analyse chromosomique</a>, qu’elle soit réalisée au moyen d’un échantillon sanguin, de cellules prélevées du liquide amniotique ou du placenta, est précise à plus de 99,9 %.</p>

 

 

Trisomy 18 (Edwards syndrome)875.000000000000Trisomy 18 (Edwards syndrome)Trisomy 18 (Edwards syndrome)TEnglishGeneticsChild (0-12 years)BodyNAConditions and diseasesCaregivers Adult (19+)NA2016-07-19T04:00:00ZDavid Chitayat, MD, FABMG, FACMG, FCCMG, FRCPC11.000000000000046.0000000000000902.000000000000Health (A-Z) - ConditionsHealth A-Z<p>Information for parents about trisomy 18, a rare genetic condition that causes developmental delay and affects many different organ systems.</p><h2>What is a trisomy?</h2><p>The term trisomy (say: TRY-so-mee) means that there are three <a href="/htbw?module=genetics">chromosomes</a>, rather than the usual pair of chromosomes. For example, a baby with <a href="/Article?contentid=9&language=English">Down syndrome</a> usually has three copies of chromosome 21, rather than the usual pair. The condition is thus called "trisomy 21."</p><h2>What is trisomy 18?<br></h2><p>Trisomy 18 is a rare chromosome abnormality that affects approximately one in every 6,000 to 8,000 live births. These children have developmental delay, as well as birth defects and health problems involving nearly every organ system in the body.</p><p>Trisomy 18 is also called Edwards syndrome, after the physician who first described the disorder.<br></p> <figure class="asset-c-80"> <span class="asset-image-title">Edwards syndrome </span><span class="asset-image-title"></span><span class="asset-image-title"></span><span class="asset-image-title">karyotype</span><img src="https://assets.aboutkidshealth.ca/akhassets/Trisomy_18_Edwards_syndrome_MED_ILL_EN.jpg" alt="The pairs of chromosomes in a female with an extra copy of chromosome 18" /><figcaption class="asset-image-caption">People</figcaption><figcaption class="asset-image-caption"></figcaption><figcaption class="asset-image-caption"></figcaption><figcaption class="asset-image-caption"> with Edwards syndrome have an extra copy of chromosome 18.</figcaption> </figure><h2>Key points</h2> <ul> <li>Trisomy 18 is a rare condition caused by an extra copy of chromosome 18.</li> <li>Children with trisomy 18 have severe developmental delay, as well as severe birth defects and health problems involving nearly every organ system in the body. </li> <li>It is difficult to predict the life expectancy of a baby with trisomy 18.</li> <li>Parents of a baby with trisomy 18 are encouraged to seek genetic counselling.</li> </ul><h2>Signs and symptoms of trisomy 18</h2><p>Babies with trisomy 18 have low birth weight, have a weak cry and startle to sound. They have problems feeding and fail to thrive. They have a small head size, with a prominent back of the head (occiput). Their ears are usually low-set and the openings of their eyes, their nose and their mouth are small. Their sternum (breastbone) is typically short. Almost all babies with trisomy 18 have <a href="/Article?contentid=1600&language=English">heart defects</a>. They have clenched fists from before birth and extending the fingers fully is difficult. Their elbows and knee joints are in a bent position rather than relaxed. They typically have club feet and their feet have been described as a “rocker bottom” due to their shape. Babies with trisomy 18 may also have <a href="/Article?contentid=371&language=English">spina bifida</a>, <a href="/Article?contentid=380&language=English">cleft lip and palate</a>, eye problems and hearing loss. Some develop <a href="/Article?contentid=2060&language=English">seizures</a> in the first year of life, <a href="/htbw?module=kidney-child">kidney</a> problems and <a href="/article?contentid=2006&language=English">scoliosis</a> (curvature of the spine).<br></p><p>Feeding difficulties, heart problems and an increased susceptibility to infection are factors which contribute to the death of children with trisomy 18.</p><h2>What causes trisomy 18?<br></h2><p>Usually each egg and sperm cell contains 23 chromosomes. At the time of <a href="/Article?contentid=310&language=English">fertilization</a>, the sperm and egg unite and create a cell with 23 chromosome pairs, or 46 chromosomes. In this manner, a child receives exactly half of their genetic material from each parent. </p><p>Sometimes, an error occurs when the egg or sperm cell is forming, causing it to have an extra chromosome. When this cell contributes the extra chromosome 18 to the embryo, trisomy 18 results. The extra chromosome 18 can come from either the mother’s egg cell or the father’s sperm cell. The abnormalities seen in babies with trisomy 18 result from having this extra chromosome 18 in each of the body’s cells.</p><p>Rarely, mosaic trisomy 18 may occur when the error in cell division occurs after fertilization. These babies have some cells with an extra chromosome 18 and others with the normal number. These babies usually have milder forms of trisomy 18. </p><h2>Diagnosis of trisomy 18</h2><p>Babies with trisomy 18 have a unique group of characteristics and can be diagnosed by physical examination. To confirm the diagnosis, a small blood sample can be taken and the chromosomes can be analyzed to determine the presence of an extra chromosome 18.</p><p>Chromosomal abnormalities can also be diagnosed before birth by analyzing cells in the amniotic fluid obtained by <a href="/Article?contentid=342&language=English">amniocentesis</a>, or from the placenta, obtained by <a href="/Article?contentid=342&language=English">chorionic villus sampling</a> (CVS) or from the fetal blood obtained by cordocentesis. Screening for trisomy 18 is also available through first trimester screening (FTS), integrated prenatal screening (IPS) or by non-invasive prenatal testing (NIPT). The diagnosis of trisomy 18 can also be suggested by detailed <a href="/Article?contentid=342&language=English">fetal ultrasound</a>; however, ultrasound is not 100% accurate, since not all abnormalities can be seen on ultrasound and the same abnormalities seen prenatally in trisomy 18 can also be seen in other conditions. In contrast, a <a href="/htbw?module=genetics">chromosome analysis</a>, whether performed on fetal/newborn blood sample, cells from the amniotic fluid or placental sample, is over 99.9% accurate.</p><h2>Life expectancy of a baby with trisomy 18</h2><p>Fifty per cent of babies born with trisomy 18 survive beyond their first six to nine days. About 12% of babies born with trisomy 18 survive the first year of life. It is difficult to predict the life expectancy of a baby with trisomy 18 if the baby does not have any immediate life-threatening problems. For babies that have survived their first 30 days of life, 36% were alive at one year. About 10% of children born with trisomy 18 survive until 10 years of age. </p><h2>There is a small chance of having another child with trisomy 18</h2><p>The risk of having a baby with trisomy 18 increases with the mother’s age. However, the average age of the mother at delivery of a baby with trisomy 18 is 32 years. In general, in each subsequent <a href="/Article?contentid=316&language=English">pregnancy</a>, the chance of having another baby with trisomy 18 is no greater than 1%. </p><h2>Genetic counselling is recommended</h2><p>Parents of a baby with trisomy 18 are encouraged to seek <a href="/Article?contentid=343&language=English">genetic counselling</a>. This can help parents to:</p><ul><li>understand the results of chromosomal tests in detail</li><li>understand the chances that other babies will be affected</li><li>understand the diagnosis options for other pregnancies</li></ul>https://assets.aboutkidshealth.ca/akhassets/Trisomy_18_Edwards_syndrome_MED_ILL_EN.jpgTrisomy 18 (Edwards syndrome)False

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