Question: How to draw gene expression heatmap ?
0
gravatar for scheme4193
4 months ago by
scheme419340
scheme419340 wrote:

I want to draw heatmap using differential expression genes.

First, I mapped using hisat2, and then counted genes using htseq. From this expression count matrix, I used DESeq2 to detect DEGs.

Now I have DEG list. I want to draw heatmap about these DEGs.

Which expression value do many people use to draw heatmap ? In my pipeline (hisat2 → htseq-count → DESeq2), which data can be used to draw genes expression heatmap ?

rna-seq next-gen R gene • 274 views
ADD COMMENTlink modified 4 months ago by Kevin Blighe51k • written 4 months ago by scheme419340

Depends of what you want to show. Usually heatmap are made on the log of the counts

http://bioconductor.org/packages/devel/bioc/vignettes/DESeq2/inst/doc/DESeq2.html#heatmap-of-the-count-matrix

Something like :

pheatmap(log2(counts(dds, normalized=TRUE))...)
ADD REPLYlink written 4 months ago by Bastien Hervé4.5k

Thank you for your reply ! I appreciate you sharing URL. I will use it as a reference.

ADD REPLYlink written 4 months ago by scheme419340
1
gravatar for Kevin Blighe
4 months ago by
Kevin Blighe51k
Kevin Blighe51k wrote:

You just need to subset your normalised expression data (in DESeq2, it is returned by counts(dds, normalized=TRUE), as pointed out by Bastien), but you can also use the normalised and then transformed expression data - these are produced via rlog() or vst(), then accessed via assay(). For example:

rlogcounts <- rlog(dds, blind = FALSE)
dataHeatmap <- assay(rlogcounts)

There is no standard for what to actually use in a heatmap. You can just use whatever you want. I have seen a wide range of things:

  • binary data
  • raw counts
  • normalised counts
  • log-normalised counts
  • normalised, transformed counts
  • log [base 2] ratios
  • Z-scores

You just need to specifically state what it is that you are using.

There is a wealth of information at your fingertips via a search engine, too.

Kevin

ADD COMMENTlink written 4 months ago by Kevin Blighe51k
1

Thank you for your polite reply. So, there are no uniform indicator. I'm going to try some scores. Thank you !

ADD REPLYlink written 4 months ago by scheme419340
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