[tri-med] Re: nominclature question

----- Original Message ----- 
From: <Annee122884
>> Holly, you write that Morgan has partial
> t18q and partial monosomy 9p.  What do the "t", "q", and "p" stand for 
> before
> and after the numbers?

t = trisomy (duplication)
p = the p arm of the chromosome (p stands for petite or the short arm)
q = the q arm of the chromosome (q because its the next letter after p)
m = mosaic
the number is of course the number of the chromosome involved.
monosomy - means a deletion or missing part of the chromosome. (missing a 
whole chromosome -autosome not a sex chromosome - is universally fatal, the 
embryo fails to develop)
partial means part of the chromosome, usually part of either the short arm 
(p) or part of the long arm (q)
So to clarify even further - if someone writes t18p they would technically 
have a trisomy of the p arm of the 18th chromosome from the centromere (the 
pinched bit in the middle) to the end
If they write partial t18p they would have a trisomy (duplication) of PART 
of the p arm (as opposed to the whole of the p arm)
Lots of folk write full trisomy 18 (or whatever number) which is actually a 
misnomer for what they are trying to say which is non-mosaic. Thats because 
full indicates a duplication of the whole chromosome (as opposed to a 
partial duplication).
If they feel that the t-18 (or whatever number) needs clarifying then it 
should be written as non-mosaic but then again I am being pedantic.
Aussie Alex is mosaic, however he has a duplication of a whole chromosome 
(as opposed to part of a chromosome), so technically he has a "full" trisomy 
18, but it only occurs in some cells (mosaicism).
No one can ever guarantee that any child has 100% of their cells with the 
additional chromosome because 99% of the time they only ever have one system 
tested - usually blood. There are quite a number of documented cases where 
there have been 100% of a persons blood cells tested that reveal a trisomy 
yet skin, kidney, liver etc show a totally different result. But these 
systems are not normally tested until an autopsy is done because of the 
invasiveness of the testing.
Recently I had more chromosome studies on Alex, which just serves to 
compound the whole issue for us but also illistrates the issue. This time I 
had urine done and it shows 100% of the cells with trisomy 18. I am waiting 
on a repeat testing to confirm or deny but its sure making things 
interesting :-))
Alex's studies so far show
Test 1 - blood - 0% trisomy
Test 2 - blood - failed to culture
Test 3 - blood - 61% trisomy 18
Test 4 - blood - 84% trisomy 18
Test 5 - skin - 0% trisomy 18
Test 6 - urine 100% trisomy 18
Test 7 - ???????

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

Keep Looking For Rainbows!!
   _--_|\
 /Karen \
 \ _.--._ /
          v Karen, Mum to Alex (11 years, T-18 Mosaic)
http://members.optushome.com.au/karens

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

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