Samples spiked in libary sizes using DESeq2 normalization

Question

[asrour]

Hi guys,

I am using DESeq2 to normalize my samples collected from different tissues , and I am interested in plotting the expression of genes across different tissues using the normalized counts. One group of samples coming from the same tissue increased multiple of times in library sizes after normalization way above the median of the rest of the samples. I haven't seen this before, when I checked these samples before normalization it was clear a large percentage of genes are not expressed (15-20%) compared to other tissues. However, one would not expect this overcorrection by multiple times. Is this normal? and what would be the best way to deal with it?

I appreciate any suggestion,

Best, Ali