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Can I assume my target RNA is intact if I get a high RIN number for my RNA sample?

“RNA Integrity Number” or RIN is a measurement developed by Agilent and generated by their bioanalyzer instrument based on a comparison of an RNA sample’s 5S and 18S rRNA peaks, between the 18S and 28S rRNA peaks, and after the 28S rRNA peak. A RIN number of 10 is a perfect score. However, a high (e.g., >7) RIN for your RNA sample doesn’t mean your target transcript is intact. There can be differential degradation from 5’ to 3’ across different transcript species. Also RNA that is not completely denatured and sheared single-stranded genomic DNA can migrate near the 28S rRNA peak, confounding the RIN assessment. In addition, peaks generated by additional, abundant RNA bands, such as those from chloroplasts or a symbiotic RNA, and prokaryotic samples may produce misleading RIN results. Visual assessment of degradation is a more telling sign of RNA sample quality.