What is Robertsonian translocation Down syndrome?
The Robertsonian translocation is unbalanced and the baby has three copies of the long arm of chromosome 21 instead of two. This causes a type of Down’s syndrome called translocation Down’s syndrome. The effects on the baby are exactly the same as when Down’s syndrome is caused by having an extra entire chromosome 21.
How does Robertsonian translocation occur?
A Robertsonian translocation results when the long arms of two acrocentric chromosomes fuse at the centromere and the two short arms are lost. If, for example, the long arms of chromosomes 13 and 14 fuse, no significant genetic material is lost—and the person is completely normal in spite of the translocation.
Can people with Robertsonian translocation have children?
Many people with Robertsonian translocation have healthy children. The condition can, however, impact on their chances of having a family. Women with the translocation may find it difficult to get pregnant. They also have a higher chance of having a miscarriage than those without Robertsonian translocation.
Can you get pregnant with Robertsonian translocation?
Male carriers of Robertsonian (ROB) translocation can have infertility and are shown to have abnormal semen analysis. Some patients have positive sperms in the ejaculate. Therefore, fertility management can be offered to couples to achieve pregnancy and delivery of healthy neonates.
How rare is balanced translocation?
Although about 1 person in 500 has a translocation, we still do not really understand why they happen. We know that chromosomes seem to break and rejoin quite often during the making of sperm and eggs or around the time of conception, and it is only sometimes that this leads to problems.
Can balanced translocation cause Down syndrome?
Yes. Translocation Down Syndrome is the only type of Down Syndrome that can be passed down from a parent who does not have features of Down Syndrome. If a parent has balanced translocation, there is an up to 15% chance of having another child with Down Syndrome.
How are reciprocal and Robertsonian translocations different?
There are two main types of translocations: reciprocal and Robertsonian. In a reciprocal translocation, two different chromosomes have exchanged segments with each other. In a Robertsonian translocation, an entire chromosome attaches to another at the centromere.
How does Robertsonian translocation lead to trisomy?
Translocation Down syndrome Most cases are caused by having three rather than two copies of chromosome 21. Experts call this trisomy 21. Sometimes, Down syndrome occurs when part of chromosome 21 fuses with another chromosome. Scientists call this translocation Down syndrome, which accounts for just 3–4% of cases.
Qu’est-ce que la trisomie 21 par translocation?
La Trisomie 21 par translocation représente environ 2% des cas. La «translocation» signifie le transfert d’un segment de chromosome vers un autre chromosome. Ceci est très important car la trisomie par translocation comporte un risque de récurrence dans une famille ayant déjà un enfant atteint de trisomie 21.
Qu’est-ce que la translocation?
La «translocation» signifie le transfert d’un segment de chromosome vers un autre chromosome. Ceci est très important car la trisomie par translocation comporte un risque de récurrence dans une famille ayant déjà un enfant atteint de trisomie 21. Cette translocation survient sélectivement et sur certains chromosomes (dont le 14, le 21).
Quelle est la trisomie la plus fréquente?
La plus fréquente est la trisomie 21 libre, complète et homogène : elle représente environ 93% des cas de trisomie 21. Contrairement à ce qui est souvent dit, il n’existe pas de degrés dans la trisomie 21.
Quels sont les différents types de trisomie 21?
Il existe trois formes de Trisomie 21: la Trisomie 21 libre (96% des cas); la Trisomie 21 en mosaïque (2% des cas); la Trisomie 21 par translocation (2% des cas).