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Genome Assemblies

The GRC has built tools to facilitate the curation of genome assemblies based on the sequence overlaps of long, high quality sequences (Clones and PCR products, not short sequence reads). The GRC currently supports production of assemblies for human, mouse or zebrafish. If your assembly data fits this model and you are interested in using these tools please contact us using the 'Contact Us' page. Subscribe to the grc-announce email list to receive email notification for all GRC assembly updates.



The human genome assembly was produced as part of the Human Genome Project (HGP). The previous assembly (NCBI36) was the last one produced by the HGP and was described in 2004 (PMID: 15496913); this was the starting point for the GRC. The assembly is based largely on assembling overlapping clone sequences.

Human assembly information
Current Major Assembly GRCh38
Regions with Alternate Loci 178
Assembly N50 67,794,873 bp
Remaining Gaps 875
Patches Released Fix: 13, Novel: 3


The GRC has produced an updated assembly (GRCm38). This is an update of the last MGSC assembly (MGSCv37) which was described in 2009 (PMID: 19468303). The primary assembly is based on assembling overlapping BAC clones derived from the C57BL/6J strain and several loci have sequence available from other strains.

Mouse assembly information
Current Major Assembly GRCm38
Regions with Alternate Loci 70
Assembly N50 54,517,951 bp
Remaining Gaps 628
Patch Release Version p3
Patches Released Fix: 16; Novel: 1


The zebrafish genome assembly was produced at the Sanger Institute. The last assembly produced from the original project was Zv9 and was described in 2013 (PMID: 23594743). This assembly is the starting point for the GRC. The assembly is based on assembling overlapping BAC clones and integrating these sequences with the whole genome shotgun assembly.

Zebrafish assembly information
Current Assembly GRCz10
Regions with Alternate Loci 0
Assembly N50 2,181,225 bp
Remaining Gaps 21,794

Page last updated: July 12, 2013