The National Center of Biotechnology Information (NCBI) website has recently posted a new build of its HomoloGene resource, which incorporates the latest UniGene cluster assemblies. HomoloGene allows users to quickly find orthologs – on the basis of cross-species sequence similarity – among the human, mouse, rat and zebrafish genes represented in NCBI's UniGene clusters and LocusLink site.

Each HomoloGene report consists of a UniGene cluster or LocusLink entry that forms a report's ‘base cluster’. To this base cluster are added its published and calculated orthologs. Calculated orthologs are generated by comparing nucleotide sequence in the base cluster with those in clusters from other organisms, and the report lists the best of these alignments.

To date, HomoloGene contains over 71,000 reports, and fly sequences in LocusLink have now also been added to them, providing one more species for comparative analysis.