NCBI has announced that we will be changing the way we handle GI numbers for sequence records in September 2016. (Read more, in case you missed it).

In this post, we’ll address a key question:

What is the future of existing GI numbers?

The short answer is that nothing is happening to these GI numbers.

If a nucleotide or protein record already has a GI, it will continue to have that GI indefinitely. You will also be able to retrieve such a record using its GI either on the NCBI web site or using the E-utilities.

Moreover, GIs will remain part of the XML and ASN.1 formats of sequence records.

If not GIs, then what?

Accession.version identifiers. All sequence records, both new and old, will have a unique accession.version identifier.

Existing records will keep the accessions they already have; new sequences will only receive an accession.version identifier.

So what’s all the fuss about?

Two things:

• GIs will no longer appear on flat file or FASTA data displays after September 2016. The GIs will still exist, but they won’t be visible.
• More and more new sequence records will not be assigned a GI. This means that over time, you will be missing more and more new sequences if you only use GIs.

Stay tuned for additional posts about this topic, and please contact us if you have questions.

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