DGE genes are not available in GSEA

Question

[Lawrence]

Hello everyone,

I am a beginner in bioinformatics and doing my master thesis. I am performing DGE (Differential Gene Expression analysis) on an RNA-seq dataset. I have got around 500 genes after filtering. I also did a GSEA on these 500 genes and got around 78 enriched gene sets. But, I am not able to find the 500 genes in these 78 genesets, only 10-15 genes are found in the 78 genesets along with their ontological descriptions.

So, my examiner question me about what happened to the remaining genes and how can I get ontological information about them from GSEA?

Thanks in advance.

Best regards Lawrence