Fold change >1 when no cell expresses the gene

[teresamribeiro]

Hi all
I ran into a question when using FindAllMarkers(). While looking for a specific marker I noticed than the results I got for one of the clusters were:

avg_log2FC = 2.159
pct.1 = 0.000
pct.2 = 0.061

If I understand correctly, pct.1 corresponds to the percentage of cells in said cluster that express the gene, and pct.2 corresponds to the same but for the cells in all the other clusters. How is it possible that I'm getting an avg_log>1 in a cluster where no cells express the gene? This cluster is extremely small (less than 20 cells), so it's not possible that this is the result of an approximation in its cell percentage.

Any help is greatly appreciated