This family represents the microRNA (miRNA) lin-4 (MIPF:MIPF0000303). lin-4 was identified from a study of developmental timing in C. elegans [1], and was later shown to be part of a much larger class of non-coding RNAs termed miRNAs [2]. miRNAs are transcribed as ~70nt precursors (modelled here) and subsequently processed by the Dicer enzyme to give a ~22nt product. The extents of the hairpin precursors are not generally known and are estimated based on hairpin prediction. The products are thought to have regulatory roles through complementarity to mRNA. The involvement of Dicer in miRNA processing suggests a relationship with the phenomenon of RNA interference.