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tophat/cufflink slog fold change +/- inf
Dear all,
I am using latest tophat/cufflinks suite.
A differentially expressed gene has FPKM values of 0 and 34 in two samples A and B. The log2fold change gives me +infinity. Similarly, 28 and 0 makes it -inf.
How do i interpret these +/- infinity log fold changes.
particularly, what does FPKM value of 0 mean for a sample ? does it mean there is no mapping reads for that gene but then it is statistically significant - how is it possible ?
Also if the log2fols change value is +infinity, does it mean that the gene is expresed in sample2 and completely absent in sample 1 ?
please let me know.
Thanks
Regards,
KM
I am using latest tophat/cufflinks suite.
A differentially expressed gene has FPKM values of 0 and 34 in two samples A and B. The log2fold change gives me +infinity. Similarly, 28 and 0 makes it -inf.
How do i interpret these +/- infinity log fold changes.
particularly, what does FPKM value of 0 mean for a sample ? does it mean there is no mapping reads for that gene but then it is statistically significant - how is it possible ?
Also if the log2fols change value is +infinity, does it mean that the gene is expresed in sample2 and completely absent in sample 1 ?
please let me know.
Thanks
Regards,
KM