ANA Discussion Forum
General Category => NF2 => Topic started by: NF-2er on June 25, 2007, 09:48:00 am
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Hi;
In thinking about herditary diseases and that 50% of NF-2 cases are inherited, I wonder if scientists have ever experimented with the below? There is currently a shark in a zoo which was found to be pregnant. Sharks do not cross breed ( no case ever reported ), so, how did the female develop this now nearly fully developed shark yet in her uterus? Thoughts?
NF-2er
Parthenogenesis
In parthenogenesis ("virgin birth"), the females produce eggs, but these develop into young without ever being fertilized.
Parthenogenesis occurs in some fishes, several kinds of insects, and a few species of frogs and lizards. It does not normally occur in mammals because of their imprinted genes. However, using special manipulations to circumvent imprinting, laboratory mice have been produced by parthenogenesis. [Link]
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Hi;
Just wondering if my point wasn't well made to be understood?
NF-2er
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Something we have to get used to - such a rare condition
insight and understanding is rare too
- dont get me wrong, plenty of sympathy and well wishes here
But to really understand NF2 and the genes thing you
seem to need to spend most of one lifetime studying it.
Answer to question : there is a possible answer
in the human cases of new/founders
the fault line in the gene/chrome assembly is said to happen
very early as the eggs/cells are dividing - maybe 1-36 hrs old
The fault isnt inherited - it creates itself during the growing process
- it may then be passed on to the next generation
I dont entirely go with the 50/50 passed on numbers either
- at roughly 1:40,000 the numbers are currently just TOO small
to have that kind of pass-on rate
In Theorey you would reach a point where 1 in 10 or more
would have the problem - and quite quickly
We do not have the whole puzzel yet
On that happy note....
Have good weekend !
Tony
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Gawd knows was my first answer to the first post on this thread, and then I thought hmmmmm.... mice too?.... amazing truly.....
then i figured genetics and more study focused on time would maybe find the answer....
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How about that sharks lay eggs so they don't have uteruses in the sense of how we think uteruses are?
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You say sharks do not cross breed, but do they cross dress?
Capt Deb
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I know sharks have crossed my grill and hot coals more than once and yummmm!
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Hope you de-uteresed it first!
Capt Deb
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cross dressing sharks with no uteruses ??? I'll google that and see what I come up with
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Hi;
I see my point was entirely missed and made light of.
If... In the future a couple wished to have a child and the male was a known NF-2 carrier, the woman ( with the help of science ) may be able to develop an embyro w/o fertilaztion by the Father. Thus, a far smaller chance of the newborn having NF-2.
Re: Research, it has also been determined that vestibular nerves can be grown from the stem cells of 2nd and 3rd trimester fetuses. An ethical issue for sure.
Maybe a section could be added for research and/or the future.
NF-2er
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Actually they talked a lot about NF-2 and genetics at the Symposium, should have been there, they have some new views on it now that there is 3 distinct forms identified. I don't think "virgin birth" is the answer, nor is growing vestibular nerves as the vestibular nerve may not be the only nerve affected in NF2s.
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.... so is this "semantics" for non scientists like Aners on boards for support, I wonder ?... so..... if, when one has an acoustic neuroma "growing from one cell gone wrong" on the "hearing" nerve, is this different from a grown-wrong cell leading to an acoustic neuroma that maybe began from oh i dunno, some "one - cell" gone wrong nearby like on the facial or any one of the nerves that are closely winding their way through that area?? that all end up being diagnosed as an Acoustic neuroma??
HI nf2er... genetics is fascinating for both researchers and ordinary folks who read whatever they can about it..... I don't doubt that an nf-er would be thrilled not to pass on any genetic component that might lead to an nf2 diagnosis for any offspring some years down the road..... a lot of cells can be grown from 2nd or 3rd trimester fetuses in genetics studies.....
so are you saying that genetics might answer things for anyone who has an An?
when reading Tony's post above in this thread it sounds like this thing is not inherited but happens after fertilization during the growing process and thus is not exactly passed on in some inherited fashion? from that but is something that happens during the growing/dividing time of the initial fertalized cells and then may be passed on? but even that is not exactly sure?
maybe that helps out nf2er about the 50-50 thing?
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Sorry - this is the issue with NF2 type stuff - its almost
all full of conditions and provisos etc etc
Anyway yes SOME NF2 are first instance (Founders)
- were not inhertited - but can be passed on to next generations
Others ARE inhertited and they too can be passed on
Overall pass on rate is said to be 50/50
but there are wild varations - and the stats
are so small as to be statistically misleading
Stats are a real issue here - hard to collate
and even harder to draw conclusions
As to three types - not surprised
Used to be NF1 and NF2 were the same
Then they defined the two as different
Then NF2 was divided into two
I actually think there might be another two
or three versions
I think there is one that would show up at 150yrs old (ish)
(a very slow growing version)
- but since no-one lives that long it does not reveal itself
It might explain the strange clusters (genetically speaking)
of single side ANs (never actually diagnosed as NF2 )
Final thought - transmission rate of 50% ?
half the world would have it within 100 yrs....
as its still around 1 : 40,000
Theres a big bit missing from the puzzel
Confusing isnt it ?
Tony
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Dr Slattery also talked some about the types of NF2,besides what we heard in the general session.
I had never heard of the segmental type. I also did not retain what was said about it being on only parts of the chromosones so causes less severe type? I am not sure if that is right. I wish I had took notes. I think I will retain this stuff and by now I should know better that i will not. I am not an auditory learner and need to see it. I wish they gave handouts with with they talked about in some cases.
Cheryl R
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Good point CherylR! I too would like to "read over" at a later date the session I attended. SIGH!
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Cheryl, that other type I think you're talking about was when they were discussing "mosaic" NF2. That would be, for example, when the "mutation" would occur after several cell divisions have already occurred, so chromosome 22 would be normal in some areas of your body, and show signs of NF2 in others...therefore, you could have benign tumors in only one or several "mosaic" areas of your body. I remember that in relation to someone asking about some benign tumors she had in her foot and how that could relate to NF2.
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Hi;
Yes, the gene marker for NF-2 only takes a small segment. I believe 12.2. There are many other chromosome 22 diseases unrelated to NF-2 and 'seemingly close', but actually very far away from the defective gene area.
Inherited, and severe NF-2 is of the "Wishart" variety and the more mild and probably new mutation NF-2 is known as the "Gardner Variety". There are about 6 sub-divisions between.
The formation of a unilateral, one time, spontaneous AN is exactly the same as for an NF-2 mediated AN however.
In the distant future, I can envision "virgin birth" type provocations for certain, difficult illnesses and anxious to be parents, couples. We've already surrogates.
Guess I'm not a research scientist so best make this my last post, re NF-2.
NF-2er
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Last post ? - thats sounds a bit heavy...
I hope you are alright
(or as well as can be expected ?)
Best Regards
Tony