Saturday, January 15, 2011

Mosiac Down Syndrome

I often get asked if I am sure Fiona has Down syndrome. Even a few doctors argued with me that she doesn't look like she has Downs. I am not sure if I ever touched on this subject before, but there is a medical reason why Fiona doesn't have very many physical characteristics of the disorder.


Fiona has a type of Down syndrome called mosaic Down syndrome. Only 1-4% of all people with Downs have this form of it, different sites have told me different numbers. Mosaicism is very under studied. People with mDs have a percentage of cells with an extra copy of the 21st chromosome and the remaining cells are unaffected.taken from INTERNATIONAL MOSAIC DOWN SYNDROME ASSOCIATION In less complicated terms, only some of her is effected by Down syndrome. 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. taken from HERE



The fact that she has such few physical markers has always been something that intrigues me. I google images of people with Downs, searching for others who have the syndrome but look fairly "normal" ( I absolutely hate using that term, but its politically correct). I didn't find many, but I found some. The thing with mDs, is it is still just as unpredictable as Down syndrome. There is still a wide range of mild to severe cases. It all depends on how many of the person's cells have trisomy-21. And it also is not possible to know which cells are effected unless each and every organ is tested. That is just a lot of testing for something that, frankly, doesn't really matter. People with mosiac have the same health risks that full Downs have- the fact that Fiona had a heart condition actually implies that she has quite a lot of cells effected. Which still tells us nothing about how "severe" of a case she has. Her whole body could have T-21 except for her brain, and she could be very high functioning, or just her brain cells could have T-21 and she could be very severely mentally handicapped. So mosaic doesn't necessarily mean she will be high functioning. It does, however greaten her odds.

down syndrome baby in blue
Another sweet child with mosaic Downs. Same big, just slightly almond shaped eyes as Fiona.


There was a study done in 1991 by Fischler and Koch where they measured the IQ of 30 people with Down syndrome, some with the mosaic form, some with the usual T21. The study found that the IQ of the folks with mosaic down syndrome averaged 10-30 points higher than the others, and they speculated that this is because fewer of their cells have 3 copies of chromosome 21. The problem with drawing a conclusion from the study, though, is that the causes of Down syndrome are not simple. Not everybody expresses the same genes equally, or develops the same characteristics, even with exactly the same chromosomes! In the study I just mentioned, there was a lot of overlap in the samples; some of the people with Trisomy 21 outperformed their mosaic counterparts on the same IQ test, and vice versa. - image and info taken from BLESSED-WITH-DOWN-SYNDROME.ORG

We will learn more about Fiona's condition as she grows and developes. As of right now, she is a beautiful, high functioning little baby. And although she is slightly behind developementally then peers her age, shes not that far off track. I mean, I guess we can give the girl some slack- she did have to go through heart surgery :)


To learn more about mosaic Down syndrome, visit THE INTERNATIONAL MOSAIC DOWN SYNDROME ASSOCIATION

11 comments:

  1. She is adorable. Kamdyn has a VSD, but it has been closing on its own. I'm so glad that everything is going well.

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  2. Catching up on Fiona's story as a new reader... I had never heard of Mosaic Down Syndrome. Thanks for the education about your beautiful baby gir.

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  3. I would love to talk to you as I am suspecting this diagnosis with my son.

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  4. Tiff, I would love to talk to you. I have no way to contact you, so I hope you see this. Please email me at shannonblaeske@gmail.com

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  5. Tiff, I would love to talk to you. I have no way to contact you, so I hope you see this. Please email me at shannonblaeske@gmail.com

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  6. I would like to talk with you. My daughter was just diagnosed with ALL leukemia but she also has subglottic stenosis. She is almost 3, but because of her diagnosis (4/1/12) they are testing her for Mosaic Down Syndrome because they are two markers for kids with Down Syndrome. Like you I have been looking for kids with this and what they look like because my kid does not look like a child with Down's. You are the first website about your baby where I thought "YES, I can talk to her because her baby looks like mine!" If you could please email me back at tootz1179@gmail.com I would appreciate it :)

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  7. I would like to talk with you. My daughter was just diagnosed with ALL leukemia but she also has subglottic stenosis. She is almost 3, but because of her diagnosis (4/1/12) they are testing her for Mosaic Down Syndrome because they are two markers for kids with Down Syndrome. Like you I have been looking for kids with this and what they look like because my kid does not look like a child with Down's. You are the first website about your baby where I thought "YES, I can talk to her because her baby looks like mine!" If you could please email me back at tootz1179@gmail.com I would appreciate it :)

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  8. Shannon, I posted in your other Mds-still learning blog. As I am reading these responses I am so relieved that there are other parents out there looking, like I am, for people going through the same things I go through every day with my daughter Katie, who has MDs. She looks "normal" as you put it. Her eyes are slightly almond shaped. Fiona is beautiful and I loved looking at all the pictures you have of her. You have a beautiful family. I would love to talk to you sometime about Fiona's development. Katie is also just slightly behind on her milestones. She is walking but not at full speed and not all the time. She says some words. We have in home therapy for both every week and this has helped tremendously! God bless you and thank you so much for sharing Fiona's story with the world!

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  9. I would also like to talk to you. My son is 10 weeks old and was also diagnosed with mosaic down syndrome. So far we have not seen any effects from it.
    My name is crystal and my son is Aiden.

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  10. I would also like to talk with you. My son is 10 weeks old and was also diagnosed with mosaic down syndrome. And so far have not seen any effects

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    Replies
    1. Email me at shannonblaeske@gmail.com

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