Enriched Bar Chart on Blast2go gives percentage more than 100%

Question

[Mohamed Abderrahmane]

Hello,

I am using Blast2GO for enrichment analysis of a set of genes using Fisher's test on my transcriptome, and I am generating bar charts like this:

My question is why I am seeing "% Seqs" values greater than 100% for the last function? According to the Blast2GO documentation, "Show Bar Chart" generates a bar display showing the percentages of sequences in both the test and reference sets for each annotation in the table" doesn't the percentage of sequences means the percentage of my sequences?

Best regards,
Mohamed.

Answer 1

[Mohamed Abderrahmane]

I am providing the logical response I have so far. In fact, in 'others,' Blast2GO includes all the functions it couldn't represent on the bar plot. Since a GO term can be present in multiple genes (or contigs, in my case), their total exceeds 100%. For example, gene 1 has term GO01 and term GO02, and gene 2 has term GO02 and term GO03. In this case, GO02 is present in two genes, so when we sum all the functions, some GO terms are counted more than once.

If you have any corrections, I would be happy to hear them.