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Chicken Genome Overview

Information about the continuing improvement of the chicken genome

After the release of Gallus_gallus-5.0 in December 2015, the GRC has taken over the responsibility for the management of chicken reference genome assembly updates. GRCg6a, the latest assembly, has been refined by additional long read sequences, improvements to de novo assembly algorithms, manual annotation of de novo assembled contigs and integration of finished BAC clone sequences. GRCg6a assembly has superior metrics of quality, such as N50 contig size of 18Mb and much lower gap counts. The assembly represents the Red Jungle Fowl strain, inbred line UCD001. All sequences in the assembly are derived from a single individual from this line, female "RJF #256".

GRCg6a (GCA_000002315.5) has replaced GRCg6 (GCA_000002315.4). See the Release Notes below for additional details.

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Ideogram of the latest chicken assembly, GRCg6a


  • Release date: March 27, 2018
  • Release type: major
  • Release notes: GRCg6a is an update to the chicken reference assembly that replaces GRCg6. Chromosome coordinates in the two assemblies are unchanged. The GRCg6a update was produced to exclude four unlocalized GRCg6 scaffolds that are redundant to localized sequences on chr. W and Z (KZ626820.1, KZ626821.1, KZ626822.1, KZ626823.1). These scaffolds have been removed from GRCg6a; the assemblies are otherwise identical.
  • Assembly accessions: GenBank: GCA_000002315.5 , RefSeq: GCF_000002315.5


  • Release date: December 16, 2015
  • Release type: major
  • Release notes: This assembly was released by the International Chicken Genome Consortium. The GRC are now working to curate the chicken reference genome assembly.
  • Assembly accessions: GenBank: GCA_000002315.3, RefSeq: GCF_000002315.4