Mosaicism

[aspiringmd1015]

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COnfused on mosaicism, is it mitotic, meiotic or both, as down's can be due to mosaicism, but UW is saying its to due a nondisjunction event early on in embryonic life, i always assumed it would a mitotic error, isnt nonDJ mostly associated with meiosis?

 

[worldbeater]

For any chromosomal anomaly, it's always nondisjunction, that's your go to answer. For Down's specifically, the order is 1) nondisjunction 2) Robertson's translocation (33% of all cases I think) 3) mosaicism. The writer won't go any deeper than that.

 

[TBV]

I think mosaicism is the exception to the rule that non-disjunction = meiosis

 

[aspiringmd1015]

d

For any chromosomal anomaly, it's always nondisjunction, that's your go to answer. For Down's specifically, the order is 1) nondisjunction 2) Robertson's translocation (33% of all cases I think) 3) mosaicism. The writer won't go any deeper than that.

definitely not, Robertsonians are 5% of all cases..if it was 33% downs would be seen much more often.

 

[worldbeater]

I'll look it up:
"
1) Most common cause: Nondisjunction
2) "Robertsonian translocation; highest incidence (33% of offspring)"

That's what it says in my reading source, so I took that as meaning 33% of Down's cases

for completion sake

3) Mosaicism, based on maternal age (World Q)

 

[zhopv10]

It is 4.5% of cases says NIH, 33% of offspring in your reading may be referring to the ability to pass it on to the offspring since the translocation can be heritable? IDK


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[zhopv10]

As a side note from what I could find mosaicism can happen from either of two events: non disjunction or anaphase lag. Both of these events in the case of mosaicism occurs in mitosis early on. So it is as somebody mentioned earlier on an exception to the non disjunction=meiosis rule.


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[TBV]

Haven't looked it up but 33% should be the chance of you having the translocation passing it on to offspring.
-normal 21 & translocated 14 = downs
-short 21 & translocated 14 = normal
-Normal 21 & normal 14 = normal
Short 21 & normal 14 = non-viable?

Its from a while back can anyone confirm?

 

[worldbeater]

33% of offspring in your reading may be referring to the ability to pass it on to the offspring

Sweet, yeah that's probably it. Thanks.