Syndrome triple X 1127374 30827251 2008-06-20T16:24:07Z DumZiBoT 280295 robot Ajoute: [[it:Sindrome della tripla X]] {{ébauche|médecine}} Le '''syndrome triple X''' est une anomalie [[chromosome|chromosomale]] [[aneuploïdie|aneuploïdique]] caractérisée par la présence d'un [[chromosome X]] supplémentaire dans chaque [[cellule (biologie)|cellule]] d'une [[femme]]. Le syndrome est également appelé '''syndrome XXX''', '''trisomie X''', '''triplo-X''', '''47xxx''' ou '''aneuploïdie 47,XXX'''. Cette anomalie chromosomique se déclenche lors de la méiose. La trisomie-X apparaît lors de la division des [[gamète]]s des parents. Des femmes atteintes de trisomie-X sont typiquement grandes avec des seuils de sensibilité légèrement plus élevés, et ne présentent pas de risques accrus sur le plan médical. == Symptômes == <!--Most often, triple X syndrome causes no unusual physical features or [[medicine|medical]] problems. Females with the syndrome are usually [[human height|taller]] than average, may have [[menstrual cycle|menstrual]] irregularities, and, although rarely exhibiting severe learning difficulties (US: mentally retarded), sometimes have an increased risk of [[learning disability|learning disabilities]] and delayed speech and language skills. Researchers are not yet certain why an extra copy of the X chromosome is associated with tall stature and learning issues in some girls and women. These characteristics vary widely among affected individuals, however. Additionally, most females with triple X syndrome have normal [[human sexuality|sexual development]] and are able to [[fertilisation|conceive]] [[child]]ren.--> == Causes == <!--Triple X syndrome is not inherited, but usually occurs as a random event during the formation of [[reproduction|reproductive cell]]s ([[ovum]] and [[sperm]]). An error in cell division called [[nondisjunction]] can result in reproductive cells with an abnormal number of chromosomes. For example, an [[oocyte]] or sperm cell may gain an extra copy of the X chromosome as a result of the nondisjunction. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra X chromosome in each of his or her cells. In some cases, trisomy X occurs as an accident during cell division in early [[fetus|fetal]] development. Some females with triple X syndrome have an extra X chromosome in only some of their cells. These cases are called 46,XX/47,XXX [[mosaic (genetics)|mosaic]]s.--> Causée comme toute trisome suite à une mal-ségrégation chromosomique survenant lors de la [[gamétogenèse]] ou plus précisément l'[[ovogenèse]] (donc chez la femme uniquement) car seule la femme possède deux [[Chromosome X|chromosomes X]] dans le noyau de ses cellules. De même, comme toutes trisomies ou plus généralement toutes les [[aneuploïdie]]s, leurs occurrences augmentent avec l'âge de la mère. == Incidence == <!--Triple X syndrome occurs in about 1 in 1,000 newborn girls. Five to ten girls with triple X syndrome are born in the [[United States]] each day.--> == Liens externes == <!--* {{en}} [http://ghr.nlm.nih.gov/condition=triplexsyndrome Triple X syndrome] at the NLM Genetics Home Reference site * {{en}} [http://www.aaa.dk/turners/engelsk/triplex.htm] *Community & Support ** {{en}} [http://www.triplo-x.org/] ** {{en}} [http://www.groups.yahoo.com/group/ktxgroup/] --> {{Chromosome humain}} {{Portail médecine}} [[Catégorie:Maladie génétique|Triple X]] [[Catégorie:Maladie chromosomique|Triple X]] [[cs:XXX syndrom]] [[de:Triplo-X-Syndrom]] [[en:Triple X syndrome]] [[es:Síndrome del triple X]] [[hu:Tripla X-szindróma]] [[it:Sindrome della tripla X]] [[nl:Triple X-syndroom]] [[pl:Trisomia chromosomu X]] [[pt:Trissomia X]] [[sv:XXX syndrom]] [[zh:X-三體]]