I am looking for refseq NM_016951 but mget returns me three results, how can I get only for NM_016951 (the first one): unlist(mget('NM_016951', revmap(hgug4112aREFSEQ)) NM_016951 NM_0169512 NM_0169513 "A_23_P118061" "A_23_P206396" "A_24_P215804" thank you Marco