Primer-BLAST now has a “Primers common for a group of sequences” submission tab that allows you to design primers for a group of highly similar sequences. For example, you may want test for expression of any transcript of gene rather than a specific splice variant, so you want to design primers to cover all transcript variants.  Or you may want to design primers that will amplify the same gene in closely related bacteria strains.  To find primers for a group of related sequences, Primer-BLAST aligns the longest sequence to the rest to find common regions. It uses these to limit the locations of primers. The longest sequence is also used as the representative template sequence in the results.  Figure 1 shows an example search for primers that will amplify all of the 15 splice variants for the human TP53 gene.

Figure 1. Primer-BLAST submission page and results for primers designed for the human TP53 transcripts. Top panel: The submission form with the “Primers common for a group of sequences” selected and the 15 RefSeq transcript accessions for TP53. Middle panel: The graphical results showing the longest sequence (NM_001126114.3) as the representative template, the locations of the primer pairs, and the alignment of the other template sequences. Bottom panel: An individual primer pair showing the locations on each of the template sequences.

Please try out this new feature and let us know what you think!