[tri-med] Re: Fw: [tri-wings] An intro and questions(penny)

Original Message ----- 
From: "pam&darrell" <bifman@xxxxxxxxxxxx>
Subject: [tri-med] Fw: [tri-wings] An intro and questions(penny)


> in case no one else jumps in with an explanation of roberstsonian
> translocations i thought you could help kaylene out a bit- her note 
> follows.

I'll post Karen's explanation...nobody explains things like she does :o)
>
> and by the way, devon looks fantastic as do the rest of the family.  i am
> glad he had a good time on his big day. i love the new bear by the way. 
> what
> happened to the old one?


OH....the OLD bear is still very much present...he will always be Devon's #1 
pal! The next time his seams open up I'm ready for it! I bought some new 
stuffing called "Cluster Stuff" and I'm going to remove the hard lump that 
has become his chest and stuff him with new materials. Of course I need to 
kinda over stuff him so he feels like he does now :O) I REALLY Love the 
newest pics of him myself...the one of Devon and Nick together is my 
favorite :O)
Love, P

Here's Karen's explanation :o)

>
> Here goes!!!
> There are two types of translocations - reciprocal and Robertsonian.
> Now given the situation where this is an existing family condition so that
> there is no mosaicism involved then every sperm would carry the
> translocation in both cases.
>
> So in the case of a reciprocal translocation there are 4 possibilities for
> a
> fertilised egg
> Normal chromosomes
> Balanced translocation
> Unbalanced plus some extra chromosome
> Unbalanced minus some chromosome
>
> so the theoretical chance (and I emphasise theoretical!!!! - read to the
> end) is a 50/50 chance of there being something wrong.
>
> Now in a Robertsonian translocation there are six possibilities (I will
> use
> the example of an 18/13 translocation)
> Normal
> Balanced
> Unbalanced with an extra 18
> Unbalanced minus an 18
> Unbalanced with an extra 13
> Unbalanced minus a 13
>
> So theoretically the risks are higher however a monosomy 13 and a monosomy
> 18 are "incompatible with life" and will result in a miscarriage (possibly
> just a "late" period). So the chances are 2 to 1 of something going wrong.
>
> HOWEVER
> every situation is different!!!! and anyone with a translocation should go
> armed with their karyotype and talk specifics with a genetic counsellor.
> This is a very brief THEORETICAL overview!!!! (I spent an hour listening
> to
> the variations!!! chances of partials, "normal" risks added in etc etc.)
>
> The other be wary thing is that males who are carriers of a translocation
> have babies with problems less often than women but they HAVE NO IDEA
> WHY!!!
> Its an observation of the population not something that can be explained
> by
> science. (But can science ever explain anything fully?????)
>
> Now one other titbit of information is that because sperm are totally
> replaced every three months or so age continues to play no factor in
> increased risk with males. They use the same template all their lives and
> unless there is an environmental effect on that template they will produce
> "mistakes" at the same rate all their lives.
> It is only women who suffer the increased risks due to age and the
> splitting
> of the egg at ovulation.
> So sperm and eggs make the same number of "mistakes" up until age 35 when
> the risk increases for the eggs but not the sperm.
>
> I hope that helps :-)) and doesn't scare anyone, remember this is all
> theory
> we all know that reality is very different!!!!
>
> Take Care and Keep Looking for Rainbows!!!
> Karen, mum to Alex (5, T-18 mosaic)
>
>


                  Building ___ooOOoo__ Rainbows
                       www.trisomyonline.org
                  Families Helping Families On-line

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