Table 1.

Summary of types of sncRNAs with potential or described function across the animal kingdom. (?), function not well defined.

Name	Abbrev	Class	Length (nt)	Function	Ref
C/D snoRNA-derived RNA snRNA	C/D sdRNA	snRNA	17–19, 27	Post-transcriptional gene repression, processing of pre-rRNA	[352], [353]
Centromere repeat-associated sRNA	crasiRNA	chRNA	34–42	Heterochromatin formation	[207], [354]
Double-strand break induced sRNA	diRNA	DSB	21	DNA double-strand break repair	[355], [356], [357]
Endogenous small interfering RNA	endo-siRNA	siRNA	21–26	Inhibition of retrotransposition, pos-transcriptional gene repression	[358], [359]
Exogeneous small interfering RNA	exo-siRNA	siRNA	21	Gene silencing, anti-viral	[360], [361]
H/ACA snoRNA-derived RNA snRNA	H/ACA sdRNA	snRNA	20–24	Post-transcriptional gene repression, alternative splicing	[362], [363], [364]
microRNA	miRNA	miRNA	19–22	Post-transcriptional gene repression	[221], [365]
miRNA-offset RNAs	moRNA	miRNA	19–22	Post-transcriptional gene repression	[367], [368]
Promoter-associated small RNAs	PASRs		18–200	Transcriptional regulation	[369], [370]
Piwi interacting RNA or repeat-associated siRNA	piRNA or rasiRNA	piRNA	25–33	Germline post-transcriptional gene repression, transposon regulation, chromatin modification	[230], [242], [371]
Pyknon	Pyknon	miRNA/siRNA	16–22	Post-transcriptional gene repression	[372]
Small nuclear RNA or small Cajal-body RNA	snRNA or scaRNA		128	Pseudouridylation of U2 spliceosomal RNA (?)	[374], [375]
Splice site-associated small RNA	spliRNA	CAsRNA	17–18	Involved in regulating epigenomic modifications and transcription (?)	[376]
Stem-bulge RNA	sbRNA	Y RNA	67–133	RNA quality control, chromosomal replication	[377], [378]
Small NF90-associated RNA	SNAR			Remain to be established	[379], [380]
Small vault RNA	svRNA	vRNA	22–37	Post-transcriptional gene regulation	[381], [382]
Telomere-specific sRNA	tel-sRNA	chrRNA	24	Epigenetic regulation	[385]
Transcription initiation sRNA	tiRNA	CAsRNA	18	Transcriptional regulation	[369], [386]
tRNA derived halves	tRH	tDR	30–35	Post-transcriptional gene repression	[387], [388]
tRNA-derived fragments	tRF	tDR	20	Post-transcriptional gene repression, translational repression	[389], [390]
Transcriptional start-site-miRNA	TSS-miRNA	miRNA	20–90	Post-transcriptional gene regulation	[369], [391]
Unusually small RNA	usRNA	miRNA	15–17	Post-transcriptional gene regulation	[392]
Y RNA-derived small RNAs Y RNA	yDR	Y RNA	24–25, 30	Ro-RNA particle to control RNA quality (?) and chromosomal replication	[393], [394]