This article should be redirected to Piwi-interacting RNAs, as rasiRNAs are not a subclass of piRNAs but are actually piRNAs which were called rasiRNAs before the term piRNA was coined (see this reference: Brennecke, J. et al. (2007) Discrete small RNA-generating loci as master regulators of transposon activity in Drosophila. Cell 128, 1089–1103). Some of the content of this page is good and could be reused in the piRNA article, which is very incomplete.