[tri-med] Re: testing of cells results/Karen

Karen,
One other thing I forgot to ask. If Jonah has mosaicism does the mean it
could have been inherited or is it the same with  Trisomy 18 full just a
fluke. Assuming my husband nor I are mosaic ourselves.
Thanks Sandi
----- Original Message -----
From: "Aaron & Sandi" <asmeyerhoff@xxxxxxx>
To: <tri-med@xxxxxxxxxxxxx>
Sent: Sunday, March 24, 2002 1:29 PM
Subject: [tri-med] Re: testing of cells results/Karen


>
> I am so grateful for your response. I ma begginnig to understand some of
> this finally. Your email was not to long. There is never to much info when
> it comes to my kids. I will be calling my genetic docotr on monday, but
with
> this I will have the ability to ask better questions. I do realize the
> outcome is often the same with full or mosiacism. Our sons severe
> abnormalities tell us his chances are low of survival no matter the
defiante
> diagnosis but I just want to know.
>
> Here is someof the info you asked for:
>
> They tested amnio fluid not blood
>
> FINAL CYTOGENETIC ANALYSIS:
> 47, XY, +18    (5 cells)
>
> Cytogenetic analysis of cultured amniotic fluid at 400-450 band resolution
> showed a male karyotype with an extra chromosome 18. This finding is
> diagnostic of Trisomy 18 syndrome.
>
> My understanding is that in the FISH test they tested 100 cells. I do not
> know if that makes any difference. Also I live in Canada not the US so I
do
> not know if how they do things here is different then there.
> The flask thing I have not clue about but will ask the doctor when I call.
> I thought testing 5 cells from the full amnio (cultured) results seemed
> small but I thought it was becasue the FISH test they did 100. Should they
> be testing more cultured cells??
> I am alittle nervous about asking for retesting here becasue medical is
very
> different then in the states(I am an american living in canada).
> Thanks for all your help and time
> Sandi
>
>
> ----- Original Message -----
> From: "Karen Schuler" <karens@xxxxxxxxxxxxxxxx>
> To: <tri-med@xxxxxxxxxxxxx>
> Sent: Sunday, March 24, 2002 12:27 PM
> Subject: [tri-med] Re: testing of cells results
>
>
> >
> > ----- Original Message -----
> > From: "Aaron & Sandi"
> > > My question is does this mean the other 18% of cells are normal??? and
> do
> > not contain an extra 18
> >
> > You can ask almost anything here and someone will have some experience,
> but
> > you really need to speak with your geneticist as well. I can give you
some
> > answers, and lots of questions for your geneticist.
> >
> > The answer is maybe this is a case of mosaicism for trisomy 18 and
> probably
> > not for the sex. What you really need to find out though is what the
> > g-banding or cultured results show.
> >
> > The result that you have given is the result of a FISH test (maybe a
SKYE
> > but I would guess a FISH). Although they are widely used these days they
> are
> > still considered either experimental or at risk of innacuracy and so any
> > results from a FISH test must be confirmed with a cultured karyotype. I
> will
> > explain why in a minute.
> >
> > The cultured karyotype ALWAYS takes precedence over the FISH. So if the
> > cultured karyotype says 100% of cells showed T-18 they will consider the
> > result full T-18. If the cultured cells showed even 1 "normal" cell they
> > will consider it mosaicism.
> >
> > They may redo the test, and they may suggest other testing to confirm
the
> > results, eg if this prenatal they can either redo the amnio, do a PUBS
(or
> > cordocentesis - very high risk to the baby though). If this is after
birth
> > they may repeat the blood test and suggest a skin biopsy.
> >
> > With the results that you have there are a lot more questions I would
need
> > to know to give any real answers, and these are probably best answered
by
> > your geneticist anyway. (For example what sort of probe was used, how
many
> > cells were studied, what medium was studied, how many flasks etc) But in
> > general terms
> >
> > 99% of the cells showing both an X and Y chromsome is pretty much
> definitive
> > that the baby is a boy - 1% not showing both X and Y is simply
statistical
> > variation. The signal in the cell or cells not showing both the X and Y
> > probably just "faded" very quickly.
> >
> > 20% of the cells not showing an additional 18th chromosome is not so
clear
> > cut. It may be statistical variation it may be mosaicism.
> >
> > Personally I would be leaning towards mosaicism.
> >
> > If it were me I would be asking for a repeat test to confirm either way
> > (depending on risk factors and your own personal feelings) and I would
> > definitely not be judging anything about this baby except the babies
exact
> > medical status.
> >
> > My own personal experience (that is talking to lots of other mums with a
> > prenatal diagnosis of mosaicism) tells me that mosaicism percentages via
> > amnio are usually higher than after birth. eg IF (big IF here) this IS
> > mosaicism and its 80% in an amnio then the number of T-18 cells detected
> > after birth, in blood will be much less. I would guess somewhere around
> 50%.
> >
> > Percentage of course does not mean that the baby will not have problems,
> > statistics on survival with mosaicism are really not much better than
with
> > "full" T-18 and that life wont be hard. But it does mean that its easier
> to
> > argue with the doctors about quality of life and the prognosis
> > developmentally is usually "better".
> >
> > Although we like to think of cytogenetic tests as being is infallible
this
> > is not the case. Doctors can and do make mistakes. Test results are not
> > always 100% accurate.
> >
> > With a FISH test the chromosomes are prepared and then painted with a
> > "paint". A probe is then added to the cells that matches to the cells
that
> > they are testing for - in this case 18th chromosomes. The probe ONLY
picks
> > up signals from the chromosome, or part of the chromosome that it is
meant
> > to. For example an 18th chromosome probe will not show you that there is
> an
> > extra 17th chromosome (or missing 17th chromosome). This is why the
> doctors
> > MUST know what they are looking for.
> >
> > There is a rapid test FISH probe that is done. It detects 18, 13, 21 and
X
> > chromosome problems - but this is fairly new and still only looks
> > specifically at these chromosomes no other. (each chromosome comes up in
a
> > different colour - very pretty)
> >
> > A FISH probe cannot show you if the signal is part of a chromosome and
> other
> > finer detail. This is one reason why it must always be confirmed by a
> > cultured karyotype. So for example a FISH test will not show you if the
> > problem is a partial trisomy 18 unless they are looking for a very
> specific
> > break point, but thats a different type of probe all together.
> >
> > The glowing light that they read to count may not "take" to a few cells
> and
> > it also fades fairly quickly, this is the usual reason why FISH tests
will
> > show a false mosaicism result. Under normal circumstances you would
expect
> > any sample to lose the signal from a few cells, as with the X and Y.
This
> is
> > statistical margin of error.
> >
> > Losing 20% or there abouts of signals (especially when you only lost 1%
> off
> > the sex cells) is getting a little high. It may be statistical
variation -
> > it may be true mosaicism. You will need to discuss this with your doctor
> and
> > the lab as to what they accept as statistical error. There are NO
> universal
> > standards for this, each lab makes their own rules.
> >
> > Also what you were told by the doctor can depend on what sort of doctor
> told
> > you. Obstetricians for example often have little or no knowledge on the
> ins
> > and outs of genetics. Many wouldnt know the difference between full,
> mosaic
> > or partial if it turned around and bit them!!!!
> >
> > This signal is seen as a pretty coloured glowing light. The doctor must
> then
> > manually count how many signals that they see - in this case 82% of the
> > cells that they looked at had 3 signals instead of two from an 18th
> > chromosome.
> >
> > There was another family on the list (HI!!!) for whom I had this
> discussion
> > with my favourite and world respected cytogeneticist (a cytogeneticist
is
> > the person who literally does the chromosome test). She was happy to
> accept
> > up to 5% as a margin of error in most cases (in 500 cells), but would
> still
> > report it. However she didnt like the standards for the lab I was asking
> her
> > to give a second opinion on. She would give them at least 10% probably
> > higher on the margin of error before asking for a retest. Additionally
the
> > cultured karyotype showed full trisomy 18 (only 20 cells).
> >
> > The second opinion verdict, even though the FISH showed mosaicism of 11%
> > (that is 11% of cells had a normal 18th chromosome signal) that we
needed
> to
> > consider that the child had full T-18. Retest was not possible as the
> child
> > had passed away.
> >
> > Now that is probably a longer and more complicated answer than you were
> > asking for - sorry. And I noticed after glancing at a few mails that we
> now
> > have a resident lab person on board that may give us both some better
> > insight.
> >
> > But the bottom line from where I am sitting is that yes this may be a
case
> > of mosaism but it may not be.
> > If you have the results I would love to know - what the medium was that
> they
> > tested (eg is this blood or amnio). How many cells did they test? (eg 5,
> 20,
> > 100, 500) How many flasks did they test? (eg if they tested more than
one
> > batch of cells from the same sample - this equates with something called
> > mosaicism grade)
> >
> > And of course what were the results of the cultured karyotype? How many
> > cells did they sample? Were the cells that they tested fragile? or
> different
> > in anyway?
> >
> > BTW cultured karyotypes can also be wrong - ask Alex about that one. His
> > original test after birth showed 100% normal cells - second test showed
> 60%
> > of cells with an extra 18th chromosome. Third test showed 80% of cells
> with
> > an extra 18th chromosome. FISH test on skin showed no cells with an
extra
> > 18th chromosome but we havent repeated that one, it hurts and leaves a
> > scar..........
> >
> > When people ask me, a mother with experience of mosaicism and who went
> > through the wrong result route, and also as someone who has spoken with
> lots
> > of cytogeneticists and geneticists about mosaicism but who is NOT a
> doctor.
> > I always recommend that families ask for a minimum of 100 cells to be
> tested
> > by a regular cultured karyotype from at least 2 different flasks. With
> FISH
> > testing I recommend that they screen at least 500 cells at a reputable
> lab.
> >
> > If there is any doubt about the test results I would always go with the
> > "better" result (better than going with the wrong result) until it is
> proven
> > otherwise. Remember you also have the right to ask for the test to be
> > redone. I have seen way to many errors in genetic tests to be
comfortable
> > with just accepting that these tests are 100% reliable. They are most of
> the
> > time - please dont get me wrong, but there are so many factors involved
> and
> > they can and do make mistakes.
> >
> > I guess in some ways I have never gotten over the fact that a mum here
in
> > Australia had an amnio that showed T-13. Like the vast majority of
people
> > she went ahead and interrupted the pregnancy. Unfortunately the autopsy
> > showed no physical signs of T-13 and neither did the culture done at the
> > autopsy.......................
> >
> > Man must not allow the clock and the calendar to blind him to the fact
> that
> > each moment of his life is a miracle and a mystery.
> > - H. G. Wells
> >
> > Keep Looking for Rainbows!!!
> > Karen, Mum to Alex (7, T-18 mosaic)
> > Sydney, Australia
> > http://members.optushome.com.au/karens
> > http://www.trisomyonline.org
> >
> >                   Building ___ooOOoo__ Rainbows
> >                        www.trisomyonline.org
> >                   Families Helping Families On-line
> >
>
>                   Building ___ooOOoo__ Rainbows
>                        www.trisomyonline.org
>                   Families Helping Families On-line
>

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

Other related posts: