Question: M Value from Non-Normalized Methylated and Unmethylated Signal 450k
gravatar for christophersugai
6 months ago by
christophersugai0 wrote:

Hi all,

I'm interested in getting an M value for each cpg from an Illumina 450k array, but the data was deposited in unmethylated and methylated signal in this GEO (, is there a simple method to create the M values from this matrix, or would I have to manually input the equation into R and do sapply? In which case, it would be log2((methylated +1)/(unmethylated+1)) from pan du et al. 2016? Thanks for helping a noob out!


SAMPLE1 Unmethylated Signal

SAMPLE1 Methylated Signal

cg00035864  4327    863 
cg00050873  640 11173   
cg00061679  981 2215    
cg00063477  299 4303    
cg00121626  3382    6491    
cg00212031  3721    405 
cg00213748  391 1558    
cg00214611  4018    219 
cg00223952  7333    584 
cg00243321  5591    13
methylation R 450k • 256 views
ADD COMMENTlink modified 6 months ago by Kevin Blighe32k • written 6 months ago by christophersugai0
gravatar for Kevin Blighe
6 months ago by
Kevin Blighe32k
Republic of Ireland
Kevin Blighe32k wrote:

Yes, when reading your question, that was also my interpretation, i.e., to follow the formulae in the Pan Du manuscript: Comparison of Beta-value and M-value methods for quantifying methylation levels by microarray analysis. Coding these in R should be quite easy:

1, β (beta) value


2 M value



Best of luck


ADD COMMENTlink written 6 months ago by Kevin Blighe32k
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