Types of small RNA and the need for a separate small RNA kit

Most common types of small RNA:

Abbreviation	Name	Length	Description
miRNA	microRNA	18-25 nt	Inhibit translation of mRNA.
siRNA	small interfering RNA	20-25 nt (longer has been reported)	Cleave mRNA
piRNA	Piwi-interacting RNA	24-31 nt	Silence transposons in the germline

Why is a separate small RNA kit required? The small RNAs are too small to be captured by the Total RNA and mRNA library preparation kits. Library fragments generated from such small RNAs are not faithfully retained during bead clean-up steps.

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