The biomart approach worked it out. Thank you!
Hi: Can anyone tell me some ways to convert ENTREZID into gene symbols. I get 450 or so ENTREZIDs after RNA-seq analysis in ER fraction. I want to convert them into gene symbols. I have tried DAVID gene conversion tools, but I only get 375 output even I input 450 there. Don't know why.
Thanks,
Cai
2 answers
Try biomart.
Website
https://useast.ensembl.org/info/data/biomart/index.html
R package
https://bioconductor.org/packages/release/bioc/vignettes/biomaRt/inst/doc/biomaRt.html
Use Gene symbol as filter and then entrez id as attribute.
If an answer was helpful, you should upvote it; if the answer resolved your question, you should mark it as accepted. You can accept more than one answer if they all work.

Use org.Hs.eg.db in R. You should be able to use mapIds to get what you need. It is perfectly normal for the output to have more or fewer rows than the input, based on mapping between the IDs involved, but EntrezIDs -> HGNC symbols should be 1 to 0 or 1 mapping, so you should not see more output rows than input rows.
Log in to answer this question.