Hi I am trying to find ensemble gene ids for the 1372 mouse entrez gene ids via biomaRt. but I find different number of genes in result when I do it with biomaRt package compared to BiomaRt online tool. Strangely online tool gives atleast 10 more genes mapped with ensembl IDs, The code I use is mouse<-read.csv("TFcat_mouse_gene_symbol.txt",sep="\t",header=TRUE) ensembl = useMart("ensembl", dataset = "mmusculus_gene_ensembl") filters = listFilters(ensembl) attributes = listAttributes(ensembl) data<-getBM(attributes = c("ensembl_gene_id", "entrezgene"), filters = "entrezgene", values = mouse[,1], mart = ensembl) Let me know which one is more trustable/ updated? Konika Chawla PhD candidate Department of Biology NTNU [[alternative HTML version deleted]]