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Relative fold expression and Normalization fold expression


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#1 Afiqah Alyaa

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Posted 06 July 2012 - 03:11 AM

Hi !

I have a question regarding the analyzation of qpcr data.
How do you calculate relative fold expression and normalization fold expression ?
My samples would be tumor versus normal cells.
The tumor and normal cells were taken from different patients.

Thank you.

#2 pcrman

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Posted 06 July 2012 - 04:12 PM

You should first do normalization and the calculate relative expression.

Normalization is to normalize the expression level of your target genes to that of an internal control gene or housekeeping gene in each sample so that the level of your target gene in one sample can be compared to another. This normalization process controls for unequal RNA loading, differences introduced during RT reaction, etc.

After you have obtained normalized expression data for each sample, then you can calculate relative expression. For example, you want to set the expression level for your target gene in normal tissue as 1, you divide the expression levels from all samples by that from the normal tissue, the value you get for your tumor sample for example, 2.5, means that your gene expresses 2.5 higher in tumor than in normal.

I hope that helps.

#3 Afiqah Alyaa

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Posted 06 July 2012 - 07:36 PM

Thank you for your reply and the explaination.

Can you try and show the calculation too with the data below ? So that I can understand it more clearly.
Thank you !

Patient 1 (normal tissue)
GOI CT = 23.345
18S CT = 13.2475

Patient 2 (normal tissue)
GOI CT = 23.484
18S CT =11.9245

Patient 3 (tumor tissue)
GOI CT = 29.718
18S CT =19.3255

Patient 4 (tumor tissue)
GOI CT = 31.565
18S CT = 18.7495




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