This is a test version of Biostars. For the public version, visit https://www.biostars.org.
all genes have negative logFC edgeR

Hi, I have ran an sdgeR analysis for a set of RNA-Seq samples from an RNAi knockdown experiments - there are 3control and 3 treatment samples. Strangely, in the run results all the genes have huge negative logFC values. Do you know what might have gone wrong with the analysis?

edger

Please show code and plots, words alone cannot help debugging.

More details would be helpful, but it sounds like you are looking at the wrong comparison/contrast. For example, this is what I would see if I compare control to itself.

For example, my design compares condition to control. The control is represented by coefficient 1 and condition is coefficient 2. With the way I setup the design when I run the test and specify coef = 2 it will compare condition to control. If I compare control to itself by coef = 1 it is not proper and results in very low fold-changes

> table1 <- glmQLFTest(fit, coef = 2)$table
> table2 <- glmQLFTest(fit, coef = 1)$table
> head(table1)
                            logFC     logCPM            F      PValue
ENSMUSG00000033845.13  0.85170453 -0.9476147  3.161095975 0.081842447
ENSMUSG00000033813.15  1.63796058 -1.2257288 10.471165674 0.002216420
ENSMUSG00000025907.14 -0.04744762 -1.4859080  0.006494684 0.936108420
ENSMUSG00000090031.2   0.74307672  0.4415572  3.467670646 0.068798899
ENSMUSG00000051285.17  1.91045100 -2.0703469  8.740009379 0.004844126
ENSMUSG00000061024.8   1.45765352 -0.9993126  8.529882718 0.005339044
> head(table2)
                          logFC     logCPM        F       PValue
ENSMUSG00000033845.13 -21.44758 -0.9476147 693.1961 6.689046e-30
ENSMUSG00000033813.15 -22.11838 -1.2257288 684.3716 8.884856e-30
ENSMUSG00000025907.14 -21.98321 -1.4859080 569.5287 5.067023e-28
ENSMUSG00000090031.2  -20.18491  0.4415572 820.4644 1.565172e-31
ENSMUSG00000051285.17 -23.18911 -2.0703469 512.1814 5.112515e-27
ENSMUSG00000061024.8  -21.98225 -0.9993126 696.6826 5.984925e-30

0 answers

No answers yet.

Log in to answer this question.