Website Help System

RNAi Search

Search by RefSeq or Accession Number
When searching by RefSeq, do not include the version number. For example, if you are searching for “NM_001356.2”, simply enter “NM_001356”. Because our constructs are targeted against mRNA transcripts, all searches by RefSeq should start with “NM” or “XM”

Search using Gene Symbol
When searching by gene symbol, you must enter the NCBI official symbol. For example, the NCBI gene symbol for ”Homo sapiens DEAD (Asp-Glu-Ala-Asp) box polypeptide 3, X-linked gene” is DDX3X. A search on an alternate symbol for the same gene, such as HLP2, may result in “no matches found”. You can search NCBI ( using your gene symbol to find the symbol used by NCBI as well as any synonyms.

Resolving Multiple Accession Numbers
Many constructs in our collection will hit more than one RefSeq number. For example, the RefSeq numbers NM_001356 and NM_024005 denote transcript variants of the Homo sapiens DEAD (Asp-Glu-Ala-Asp) box polypeptide 3, X-linked gene. These two sequences are exact matches for the first 3042 base pairs and only differ in the 3’UTR. Therefore, many constructs designed to target one RefSeq will also hit the other. While Sigma Aldrich updates this information regularly, the NCBI database is continually changing. If you cannot find a match to your RefSeq, it may be necessary to search on GeneID at NCBI’s website to list all of the RefSeqs for that particular gene.