See these papers:
My understanding of 'critical genes' is as those genes, that are obligatory for the pathway to function as it was supposed to. In many cases these are regulatory genes - they may make a pathway be active and support the activity, or decrease the activity and/or suppress it.
In this article:" A pathway analysis is then often performed in order to generate hypotheses about the relevant biological functions controlled by the miRNA signature. Here we show that the method widely used in scientific literature to identify these pathways is biased and leads to inaccurate results."
Pathway analysis from lists of microRNAs: common pitfalls and alternative strategy
In this article its authors wrote: " We present an overview of the major classes of miRNA tools and databases and discuss critical issues related to their selection. "
Bioinformatic tools for microRNA dissection
Probing-directed identification of novel structured RNAs - it's not micro, sorry
I think your question is close to these posts: