My thanks to a reader who pointed out this publication covering a recent topic of discussion on the RNA-Seq Blog. (see The Magic of RNA-Seq)
This study found that for experiments performed with a small number of biological replicates, significant results may be due to biological variation and may not be reproducible; and it is impossible to know whether expression patterns are specific to the individuals in the study or are a characteristic of the study populations.
These ideas are now widely accepted for DNA microarray experiments, where a large number of biological replicates are now required to justify scientific conclusions.
Their analysis suggests that as biological variability is a fundamental characteristic of gene expression, sequencing experiments should be subject to similar requirements.
- Hansen, K.D., Wu, Z., Irizarry, R.A. & Leek, J.T. Sequencing technology does not eliminate biological variability. Nat Biotechnol 29, 572–573 (2011). [abstract]