ArrayExpress Accession Number Codes

Experiments and array designs in ArrayExpress are given unique accession numbers in the format of

• E-XXXX-n for experiments
• A-XXXX-n for array designs

XXXX represents a four letter code and n is a number e.g. E-MEXP-568, A-UHNC-18. Some experiments also have secondary accession numbers.

The four letter code in the accession number generally indicates the source of the MAGE-ML file that was used to load the data into the ArrayExpress database. Sources include our own submission tools (MEXP for MIAMExpress and TABM for Tab2MAGE) as well as MAGE-ML submitted from other organizations or microarray data management tools. The 4 letter code does not necessarily tell you which organization performed the experiment or manufactured the array design.

4-letter codes include:

Secondary accession numbers

Some experiments have a secondary accession number. This is shown below the experiment title in the browse interface.

An experiment can have a secondary accession number to show a link to another experiment or to an external data source. For example

• if the data provided is a re-analysis of another dataset, the accession number of the original experiment will be listed as a secondary accession number
• data exported from the Gene Expression Omnibus (GEO) will have the GEO series identifier as the secondary accession number, as shown in the example above. See also the How data is imported from GEO page.

Any further questions, please see our FAQ.