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  #1  
Old 08-27-2012
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Post metastatic melanoma

q) a 55 yr old male who once diagnosed for melanoma 2yrs ago comes to physician for regular follow up....he complaints that he had features of vomiting,nausea,fever and loss of wt. 2lbs since a month with increasing size of his moles....he feels he's getting anorexic as the food he tastes is bitterly odour feeling....he already received chemotherapy and radiotherapy a year ago and melanoma completely resolved....on further examination..physician confirms it as metastasis to melanoma and explains pt. that he is suffering from rare mutation of BRAF ...so he prescribed BRAF kinase inhibitor...so, what exactly consists in the BRAF mutation?
a) replacing of valine in place of glutamate
b) replacing aspartate in place of valine
c) replacing glutamate in place of valine
d) replacing valine in place of arginine
e) replacing arginine in place of aspartate
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  #2  
Old 08-27-2012
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C..............????????????
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Old 08-27-2012
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C is correct.
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Old 08-27-2012
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Aa....................


...so he prescribed BRAF kinase inhibitor...so, what exactly consists in the BRAF mutation?
a) replacing of valine in place of glutamate
b) replacing aspartate in place of valine
c) replacing glutamate in place of valine
d) replacing valine in place of arginine
e) replacing arginine in place of aspartate[/QUOTE]
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Old 08-27-2012
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Quote:
Originally Posted by imgchuchu View Post
Aa....................


...so he prescribed BRAF kinase inhibitor...so, what exactly consists in the BRAF mutation?
a) replacing of valine in place of glutamate
b) replacing aspartate in place of valine
c) replacing glutamate in place of valine
d) replacing valine in place of arginine
e) replacing arginine in place of aspartate
[/QUOTE]

confused bween A & C?
Valine is substituted for by glutamate(opposite of SCDx mutation
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Old 08-28-2012
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confused bween A & C?
Valine is substituted for by glutamate(opposite of SCDx mutation[/QUOTE]

wats SCDx mutation???
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Old 08-28-2012
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Quote:
Originally Posted by sruthi View Post
confused bween A & C?
Valine is substituted for by glutamate(opposite of SCDx mutation
wats SCDx mutation???[/QUOTE]

SCDx is sickle cell disease mutation......missense mutation...glutamate is substituted by valine at 6th position of beta globin chain
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Old 08-28-2012
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Quote:
Originally Posted by venky2600 View Post
wats SCDx mutation???
SCDx is sickle cell disease mutation......missense mutation...glutamate is substituted by valine at 6th position of beta globin chain[/QUOTE]

oh yeah!! SCD for sickle cell disease!! lol, didnt tink of dat
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Old 08-28-2012
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yes, the correct answer is C) replace of glutamate in place of valine

exactly opposite of SCDx mutation but in 600th amino acid postion ( 6th postion in beta globin chain in SCDx mutation) ....

BRAF is rare mutation seen only in patients of melanoma ,leading to early metastasis....generally, pt's with this mutation are intractable to radiotherapy....
treatment option is BRAF kinase inhibitor-----VEMURAFENIB
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Old 08-28-2012
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The answer is a

BRAF mutation - In 90% of the cases, thymine is substituted with adenine at nucleotide 1799. This leads to valine (V) being substituted for by glutamate (E) at codon 600 (now referred to as V600E) in the activation segment that has been found in human cancers.[11] This mutation has been widely observed in papillary thyroid carcinoma, colorectal cancer, melanoma and non-small-cell lung cancer

Sickle cell disease - Sickle-cell anaemia is caused by a point mutation in the β-globin chain of haemoglobin, causing the hydrophilic amino acid glutamic acid to be replaced with the hydrophobic amino acid valine at the sixth position. The β-globin gene is found on chromosome 11.
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  #11  
Old 08-28-2012
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Originally Posted by ricko335 View Post
The answer is a

BRAF mutation - In 90% of the cases, thymine is substituted with adenine at nucleotide 1799. This leads to valine (V) being substituted for by glutamate (E) at codon 600 (now referred to as V600E) in the activation segment that has been found in human cancers.[11] This mutation has been widely observed in papillary thyroid carcinoma, colorectal cancer, melanoma and non-small-cell lung cancer

Sickle cell disease - Sickle-cell anaemia is caused by a point mutation in the β-globin chain of haemoglobin, causing the hydrophilic amino acid glutamic acid to be replaced with the hydrophobic amino acid valine at the sixth position. The β-globin gene is found on chromosome 11.
yes, thanx for your explanation....but, option A says....replacing valine in place of glutamate....
option C says....replacing of glutamate in place of normal valine(which is correct)......any source can you provide for it....

"Vemurafenib only works in melanoma patients whose cancer has a V600E BRAF mutation (that is, at amino acid position number 600 on the B-Raf protein, the normal valine is replaced by glutamic acid). About 60% of melanomas have this mutation. Melanoma cells without this mutation are not inhibited by vemurafenib; the drug paradoxically stimulates normal BRAF and may promote tumor growth in such cases"...
source-----wikipedia
correct me if i'm wrong.....
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Old 08-29-2012
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u r rite i guess
BRAF kinase inhibitor (potent) which inhibits tumor growth in melanomas by inhibiting kinase activity of certain mutated forms of BRAF, including BRAF with V600E mutation, thereby blocking cellular proliferation in melanoma cells with the mutation. Does not have activity against cells with wild-type BRAF. BRAFV600E activating mutations present in ~50% of melanomas; V600E mutation involves the substitution of glutamic acid for valine at amino acid 600. The cobas® 4800 BRAF V600 mutation test is approved to detect BRAFV600E mutation.


Source Drug Monographs
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