[tri-med] Re: Do you think this suspicious?

----- Original Message ----- 
From: "Magdalena
>I found your response very interesting. But I was wondering; if this
> disorder is purely a fluke and is in the mom's ovaries since her embryonic
> development then why is there a concentration of these disorders occurring
> in babies born to older women?

No one can really explain this but it is thought to be due to differential 
selection. In short they "think" the process by which eggs mature it selects 
the "best" (meaning strongest etc) eggs first and leaves the others until 
later in life. If you look at history when women had large families the 
younger children tended to be sicker, more frail etc.

How this happens is not known. Its probably hormonal but we still don't know 
all the various hormones we have or even fully understand how hormones work. 
Perhaps the hormones of a younger woman don't mature trisomic eggs as easily 
or maybe the hormones cause a younger woman to miscarry an embryo with an 
anomaly, maybe its just an odds game and there are more "normal" eggs than 
trisomic - we don't really know. Of course its not always infallible as a 16 
year old can have a baby with a chromosomal anomaly as much as a 40 year 
old. Its just that the odds are greater for the 40 year old woman.

Whats interesting is that the research showed the trisomic eggs in the 
embryo's - it gets complicated but there is a stage during the maturation of 
the egg that a chromosomal anomaly could occur due to an uneven split of the 
chromosomes. Scientists have always said no - the trisomic chromosomes must 
have been in the egg and the research seems to be backing this up.

Of course a trisomy is not always maternal - it can be paternal but from 
memory the statistics show, in T-18/13 at least that something like 98% of 
the third chromosomes are maternal. It's not routinely tested and I don't 
advise anyone to go looking at which parent to blame - because there is no 
blame.

Life consists not in holding good cards but in playing those you hold well.
                                            -- Josh Billings

Keep Looking For Rainbows!!
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 /Karen \
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          v Karen, Mum to Alex (12 years, T-18 Mosaic)
http://members.optushome.com.au/karens

                  Building ___ooOOoo__ Rainbows
                       www.trisomyonline.org
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