Gene Set Enrichment Analysis after DESeq2

Question: Gene Set Enrichment Analysis after DESeq2

6 months ago by

Indian Institute of Science Education and Research

Hello Biostars, Can anyone tell me how to prepare input data set for GSEA after Differential Gene Expression Analysis by DESeq2? How will I rank the genes? Should I rank based on log2FC or Adjusted P value? Is there any way to generate a GSEA ready data directly from DESeq2?. I was using topGo for gene ontology enrichment analysis before and recently came across GSEA. Which one is better GO enrichment analysis or GSEA? Even after going through the papers I couldn't find a significant difference between above two.

Thank you

gsea rna-seq deseq2 geneontology • 1.3k views

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modified 6 months ago by prakash • 100 • written 6 months ago by Sreeraj Thamban • 90

6 months ago by

prakash • 100

prakash • 100 wrote:

Hi Sreeraj

Genes can be ranked based on fold change and P value and that can be used in GSEA package.

you can use this R code for this purpose.

x <- read.table("DE_genes.txt",sep = "\t",header = T)
head(x)
x$fcsign <- sign(x$log2.fold_change.)
x$logP=-log10(x$p_value)
x$metric= x$logP/x$fcsign
y<-x[,c("Gene", "metric")]
head(y)
write.table(y,file="DE_genes.rnk",quote=F,sep="\t",row.names=F)

ADD COMMENT • link modified 6 months ago • written 6 months ago by prakash • 100

in this case, what parameter should we input into GSEA?

ADD REPLY • link written 3 months ago by langya • 20

6 months ago by

Michael Love • 1.6k

United States

Michael Love • 1.6k wrote:

Here's a link to an answer I wrote a few years ago for using the gene set testing package goseq following DESeq2:

https://support.bioconductor.org/p/64811/#64815

I'm not sure what kind of input GSEA takes. I also like the methods behind ROAST and CAMERA from the limma package, but I haven't yet worked on integrating with those methods. For those two, you would need to run a limma analysis upstream.

ADD COMMENT • link written 6 months ago by Michael Love • 1.6k

Hey I noticed in the newest DESeq2 version, the default setting of fold change is not shrunken fold change, may I ask why? i thought the shrunken fold change gives you higher confidence.

ADD REPLY • link written 27 days ago by langya • 20

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