Accession number (bioinformatics)

An accession number in bioinformatics is a unique identifier given to a DNA or protein sequence record to allow for tracking of different versions of that sequence record and the associated sequence over time in a single data repository. Because of its relative stability, accession numbers can be utilized as foreign keys for referring to a sequence object, but not necessarily to a unique sequence. All sequence information repositories implement the concept of "accession number" but might do so with subtle variations.

UniProt (SwissProt) Knowledgebase
In UniProt documentation, the stated role of the accession number is "to provide a stable way of identifying entries from release to release." One entry (or record) might be associated with multiple accession numbers. Thus, in UniProt, there is no specific relationship between accession number and sequence; the primary relationship is between accession number and knowledgebase record, and a single knowledgebase record can refer to multiple sequences. In the flat version of the data, AC is the field delimiter for the accession number, the first being the "primary accession number" and all subsequent values being "seconary accession numbers". The proper key field for tracking a UniProt record is the primary accession number. The group of accession numbers associated with a knowledgebase record depends on the history of the record with respect to mergers and splits. New accession numbers arise in two main ways: new sequences (common) and knowledgebase record splits (rare).

Commonly encountered accession numbers

 * Uniprot ID
 * Unified Uniprot Accession
 * Uniprot-Swissprot Accession
 * Uniprot-Swissprot ID
 * Unified Uniprot ID
 * Refseq DNA ID
 * Entrez Gene ID
 * CCDS ID
 * Vega translation ID
 * Vega Transcript ID
 * Vega Peptide ID
 * Vega Gene ID
 * HUGO ID
 * MIM ID