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Old 03-12-2012
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DNA What type of mutation in Cystic Fibrosis?

Hi fellows,

Can you tell me what kind of mutation(s) that give rise to cystic fibrosis and its effects on the characteristics of the disease?
1. nonsense
2. missense
3. frameshift
4. others, pls specify.

Thanks.
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Old 03-13-2012
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Default I hope this will help you!

1) nonsense mutation

http://en.wikipedia.org/wiki/Nonsense_mutation
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thanks
So, you think CF is nonsense mutation, on which chromosome pls?
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The CFTR gene, found at the q31.2 locus of chromosome 7, is 230,000 base pairs long, and creates a protein that is 1,480 amino acids long.


I guess you just google about cystic fibrosis and you will get all the answer what you have.
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Quote:
Originally Posted by oksana View Post
No, it is not a "nonsenses" mutation. Nonsense is a mutation that produce a stop codon = shorter non functional protein.

In CF, 70% of the cases are sec. to a 3 nucleotide deletion = "Frame shift mutation". The F508 mutation causes abnormal protein folding --> an abnormal protein.

"Deletion or addition of a number of base pairs which are not a multiple of 3 = frameshift mutation. Frame shift mutation alters the reading frame of genetic code ---> non-functional prot." UW
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I am confused...
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Old 03-13-2012
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deletion of 3 nucleotides doesn't cause a frame shift mutation .. it is the cause of the deletion of "phenylalanine" amino acid in CF ..that would be my answer !

ps : frame shift mutation happens when u add or loss one or 2 nucleotides .. of course 4 or 5 etc etc .. but not 3 ... 6.. 9..
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Default Yes it does...

Quote:
Originally Posted by Joanna View Post
deletion of 3 nucleotides doesn't cause a frame shift mutation .. it is the cause of the deletion of "phenylalanine" amino acid in CF ..that would be my answer !

ps : frame shift mutation happens when u add or loss one or 2 nucleotides .. of course 4 or 5 etc etc .. but not 3 ... 6.. 9..
UW Q Id 805:

"F508 is the most common CFTR gene mutation in patients with CF. This mutation deletes the THREE NUCLEOTIDES THAT CODE FOR PHENYLALANINE AT AMINO ACID POSITION 508."

UW Id 1412:

The most common mutation is a codon deletion in the phenylalanine position (70%). However, frameshift mutation can also cause CF.

Correcting my error (Thank U Joanna), as you said... frameshift is 2,4,6... anything that is not a multiple of 3. However, frameshift can also cause CF but the more common cause is F508 deletion.

Hope this can help....
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Also read here
Delta F508 Cystic Fibrosis Mutation

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so its a 3-nucleotide deletion at position 508 that results in loss of phenylalanine.

what would we call this mutation?
missense?

man, i really need to brush up on biochem lol.
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Quote:
Originally Posted by Dr.NickRiviera View Post
so its a 3-nucleotide deletion at position 508 that results in loss of phenylalanine.

what would we call this mutation?
missense?

man, i really need to brush up on biochem lol.
I thought missense is substituting one aminoacid for another?
You are right nick how would we call this? is there a term? lol
CF can be caused by both a deletion of Phe (the whole codon) and/or framshift mutation.. so it really depends on what answer choices they give you
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Quote:
Originally Posted by XpaezX View Post
I thought missense is substituting one aminoacid for another?
You are right nick how would we call this? is there a term? lol
CF can be caused by both a deletion of Phe (the whole codon) and/or framshift mutation.. so it really depends on what answer choices they give you
true,

so do we just call the 508 deletion a 'in-frame deletion'? :/
or is there a name for it along the lines of nonsense, missense, etc.
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Quote:
Originally Posted by Dr.NickRiviera View Post
true,

so do we just call the 508 deletion a 'in-frame deletion'? :/
or is there a name for it along the lines of nonsense, missense, etc.
I definetely agree with you on this one, in-frame looks neat, sweet and makes sense.
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Quote:
Originally Posted by XpaezX View Post
I definetely agree with you on this one, in-frame looks neat, sweet and makes sense.

Yeap... same here.
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hey, this in frame mutation is not explained by FA.
Or does anyne know where it's mentioned?
Now we know the difference between missense vs. frameshift vs. in-frame...Feeling lucky!
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Quote:
Originally Posted by patho2012 View Post
hey, this in frame mutation is not explained by FA.
Or does anyne know where it's mentioned?
Now we know the difference between missense vs. frameshift vs. in-frame...Feeling lucky!
It has to exist somewhere is just havent be able to see it, but for the time being we can say nick coined that term
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http://en.wikipedia.org/wiki/ΔF508

(caution: not high-yield)

I guess it's two missense that cancel out, in a way... but I like "in-frame" Not sure that it was just coined, though... http://ghr.nlm.nih.gov/glossary=inframemutation

Last edited by Mondoshawan; 03-13-2012 at 10:36 AM. Reason: link
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Quote:
Originally Posted by XpaezX View Post
It has to exist somewhere is just havent be able to see it, but for the time being we can say nick coined that term
Is in Kaplan videos. Biochemistry...
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Quote:
Originally Posted by XpaezX View Post
It has to exist somewhere is just havent be able to see it, but for the time being we can say nick coined that term

HERE IT IS... DE DESCRIPTION OF IN-FRAME MUTATION in CF

http://books.google.com.tw/books?id=...brosis&f=false

http://books.google.com.tw/books?id=...brosis&f=false
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Quote:
Originally Posted by Dr. Mexito View Post
Is in Kaplan videos. Biochemistry...
In the lecture note also? Which page Dr Mexito?

FA doesn't have this

UW calls this frameshift mutation

This is probably not HY, but it's good to know the names cold.

Btw, while searching for this CF mutation, other things came up. Duchene muscular dystrophy is caused by frameshift mutation, X linked recessive. Becker muscular dystrophy is caused by in frame mutation, X linked too, but the manifestations are much milder than those of Duchene's. The explanation is due to the severity of damage caused by: frameshift > in frame. Woop woop!
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its a frameshift mutation --- there is an identical question in UW
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Quote:
Originally Posted by samaher View Post
its a frameshift mutation --- there is an identical question in UW
It's weird when UWorld makes a mistake, isn't it? Like the earth tilts...
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There are now more than 500 different mutations known to cause the CF. These mutations occur in a huge gene (>6000 nucleotides) on chromosome 7 that encodes a protein of 1480 amino acids called the cystic fibrosis transmembrane conductance regulator (CFTR).

This protein transports chloride ions out of cells. People with cystic fibrosis must inherit two mutant genes to develop the disease but these mutations need not be the same. This disease results from a number of different mutations in the CFTR gene.

The most commonly observed mutations that have been observed include deletion of a codon resulting in the deletion of the amino acid phenylalanine at position 508, a missense mutation resulting in an aspartic acid being substituted for a glutamic acid at position 551, a nonsense mutation at position 542 resulting in a stop codon instead of one that codes for glycine and hence a truncated protein and mutations at the splice sites of intron 8.
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m totally confused after so many views!!
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Default guys...u are wrong here...

FRAME SHIFT MUTATION:
DELETION of a single nucleotide causes a frame shift mutation,as does deletion or insertion of any no of nucleotides that are not multiple of three.with in a frame shift mutarion,a shift in the reading frame by one or two base pairs causes the production of an entirely different protein.(often wid a premature stop codon).

MISSENSE MUTATION:
Is a POINT MUTATION "A SUBSTITUTION"NOT DELETION that causes a codon change resulting in wrong protein being incorporated.
NONSENSE MUTATION;
A SUBSTITUTION...
SILENT: A SUBSTITUTION
HOPE this helps.
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Can someone explain this question then...
I thought it doesnt cause frameshift.. According to what I understood from kaplan...
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Quote:
Originally Posted by suka View Post
Can someone explain this question then...
I thought it doesnt cause frameshift.. According to what I understood from kaplan...
The F508 mutation causes abnormal protein folding --> an abnormal protein.
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Quote:
Originally Posted by Dr. Mexito View Post
The F508 mutation causes abnormal protein folding --> an abnormal protein.
Lol! No! Not that part... The 2nd para It says theres deletion of Phe 508. However, that doesnt cause frameshift mutation.
And here in this thread I read CF = frameshift mutation as well...
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Quote:
Originally Posted by suka View Post
Lol! No! Not that part... The 2nd para It says theres deletion of Phe 508. However, that doesnt cause frameshift mutation.
And here in this thread I read CF = frameshift mutation as well...
Oh...sorry... hahaha

70% of the times, delta mutation causes CF. However, what UW describes as frame shift mutation is actually an in-frame mutation the one that can also cause CF (less common).
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Quote:
Originally Posted by Dr. Mexito View Post
Oh...sorry... hahaha

70% of the times, delta mutation causes CF. However, what UW describes as frame shift mutation is actually an in-frame mutation the one that can also cause CF (less common).
Alright,
Thanks!
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3 nucleotide deletion on chromosome 7, nucleotides that normally code for phenylalanine.


RR p.306 5.b
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