please help me clear things!!

Kourtney - posted on 08/05/2011

My daughter has Trisomy 21, which is an extra chromosome #21 in every cell in her body. Trisomy 21 is due to either the sperm or the egg that was involved in conception having an extra #21. I am pregnant with our second baby, and our chances of having another baby with Down Syndrome are not 1% total, but 1% higher than other couples in the same age group. In other words, if the average couple in our age group had a 1 in 100 chance, we would have 2 in 100 chance. If the regular odds were 1 in 400, we would have a 5 in 400 chance (1 + 1% of 400).

For Mosaic DS, it has nothing to do with the parents, it has to do with cell division in the development of the fetus.

With Translocational, it would be the same as any other dominant genetic trait, a 50/50 shot per pregnancy if one parent is a carrier. Hope this helps.

Sylvia - posted on 06/14/2011

The majority of Down syndrome cases are not hereditary. Only in cases of Translocation Down syndrome is this then possible. These inherited cases then occur because one of the parents is a carrier. A carrier will have 45 chromosomes instead of 46 but they will have all the genetic material of a person with 46 chromosomes. Remember that in Translocation Down syndrome the extra chromosome 21 material is located on a different chromosome. A carrier will have the extra material but will have only one chromosome 21. The carrier will not exhibit any of the symptoms of Down syndrome because they have the correct amount of genetic material. However, a carrier will have an increased chance of having a child with Down syndrome. If the carrier is the mother, the chances are approximately one in five of having a child with Translocation Down syndrome, but if the carrier is the father, the odds are 1 in between 20 and 50. In cases where the carrier has no unattached chromosome 21, all the carriers' children will have Down syndrome.

The ability to have children varies among people with Down syndrome (generally they have a reduced rate of fertility). Down syndrome is also known as trisomy 21 and happens when you have three chromosomes instead of two on the 21st 'pair.' This happens when there is an error in cell division and instead of 46 chromosomes dividing into two new cells with 23 each, one of the new cells will have 24 (and therefore the extra '21' chromosome). So it's not really a hereditary thing -- the chances of giving birth to a child with Down syndrome increases after the age of 35 or so, and in general the odds are 1 in 800 of having a child with Down syndrome.

It is mostly caused by an accident of gene formation. A small percent is hereditary.

It is a genetic abnormality, but not inherited, per se.


Read more: http://wiki.answers.com/Q/Is_Down_syndro...

Sylvia - posted on 06/14/2011

Translocation occurs in approximately 3-4% of babies born with Down Syndrome. In this type of Down Syndrome a part of chromosome number 21 breaks off and attaches itself to another chromosome. Often this is chromosome number 14. This causes all cells in the body to have the extra piece of the 21st chromosome. When a child is born with this type of Down Syndrome it could mean that one of the parents is carrying chromosomal material that is unusually arranged.

Sylvia - posted on 06/14/2011

The most common of the three types of Down Syndrome is often referred to as Trisomy 21. About 95% of people with Down Syndrome have this. This type of Down Syndrome occurs because of an error in cell division. The error happens either before or at the time of conception. What happens is that a pair of the 21st chromosomes in either the egg or the sperm do not separate properly. This extra chromosome is then found in every cell in the body,thereby causing the characteristics of Down Syndrome.

Sylvia - posted on 06/14/2011

GO READ ON DOWN SYNDROME SIGHT SOME ARE INHERTED BUT BASIC T21 IS A POP UP ....Mosaicism occurs in about 1-2% of all people with Down Syndrome. In this type of Down Syndrome the error in separation of the 21st chromosome occurs in one of the first few cell divisions AFTER fertilization. This causes the fetus to have some cells with 46 chromosomes and some with 47. The cells with 47 chromosomes have one extra 21st chromosome. Because of the fact that not all cells contain the extra chromosome 21 the range of physical problems varies depending on the ratio of cells with 46 chromosomes to those with 47 chromosomes.

Christine - posted on 06/14/2011

Well i can answer all these as my lil man is the "Rare" type lol....Hes 20 months old and has Translocative 14 Downe Syndrome....which means the "extra chromosome" is just a tiny lil piece stuck to the 14th chromosome. This is a type that is genetically passed from parent to child as one parent is usually a "carrier" of the translocated chromosome. It is extremely rare that this happens and according to our genetic people this can sometimes also be linked to the even "rarer" Mosaic downesyndrome which they dont test for where im from. When they find this type of ds in a child they test the parents to see who is the carrier..becuase they would need to test the siblings of the parent that is the carrier. If one of the parents is a carrier it is believed that they have a 50% chance in each pregnancy of having another child with DS. My husbnad and i were tested and.....ta da....another VERY rare thing....neither of us are carriers haha. So what has happened in out case is about a one in a billion thing! I have never been so lucky :D. We know of a couple in our town that have 2 children with DS and though i dont know them...it would have to be due to a parent being a carrier that this has happened to them. Our Genetics counsellor said that everyone in the world has a 25% chance per pregnancy of having a baby with DS now most of those pregnancies result in a miscarriage as researchers estimate that as many as 80% of babies conceived with DS are miscarried or stillborn, and DS may cause as many as 2% of all miscarriages and 1% of all stillbirths. A person that has a child with DS has a 1% chance of having another DS baby with subsequent pregnancies as stated above. I am pregnant again and this time im going to have an amniosentesis to make sure this baby is ok because i would really like to deliver this baby in my home town and not have to go to the big city again...but i want to do whats safest for baby...so finding out is important to me. Sorry this is SOOO long lol but i felt i could give you first hand info on this subject :D.

Sylvia - posted on 05/09/2011

wot a crock

Sharon - posted on 05/09/2011

To me how can they say the DS Gene could be dormant 150 years when they didn't have genetic testing just family history and in some families they don't talk about children in the family who were institutionalized? All I know about my father had a sibling that "died at birth"? He learned not to ask or tell. My son's form of DS is the non genetic kind. I was 23 at the time I gave birth, and the genetic testing said it was normal trisomi 21. There are people who have twins and one child is normal (whatever that means) and the other child has DS. Some say it is the "unlucky roll of the dice", to me, I was lucky to have Nick because he taught me a lot about myself and others with disabilities. It is what God gives you and how you decide to take it. My step daughter has two beautiful little boys, the second child has a mole on his forehead but he has this most beautiful smile and is so good natured. A person is a person! God love them!

Heidi - posted on 05/08/2011

Right.. there is alot of rubbish out there if you randomly start reading stuff. I try very hard to do "scholarly" research, from reputable sources. Thanks to my English 102 teacher lol

Louise - posted on 05/08/2011

Heidi is right it is down to chromosones and just because it has happend once it does not mean it will happen again. The best thing to do is ask to speak to a medical professional so they can answer all your questions without having to investigate on the internet. There is alot of rubbish out there that is not true.

Laura - posted on 05/08/2011

Thanks Heidi!! I knew that it was way out but the person who said it was that convinced I doubted the research I'd done slightly!! X

Heidi - posted on 05/07/2011

It is my understanding that, although there is a form of Down's which can be inherited, that particular type is extremely rare (its not even known for sure that it can be caused by inheritance at all!). The type that carries the possibility of being inherited from the parents is called translocation, and only 3-5% of children with DS have that particular type. If an amnio is done or any other type of chromosome map after birth (which is standard to diagnose) they can tell you what type of DS your child has. Most will always be regular Trisomy 21. Its not a condition that most parents of kids who have DS carry. It is quite simply a mistake they body makes during fetal development that accidentally replicates the 21st chromosome an extra time. For every couple who has a child with DS and subsequently has another child after, 1 in 100 pregnancies result in another special angel. That's hardly 50%! I had to do a little research to answer these questions...here are the wesite links that I used so that you can look them up and read up on it.
http://www.downsyn.com/whatisds.php
http://pediatrics.about.com/od/birthdefe...

Hope this helps!