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Novel circular RNAs surprisingly abundant in platelets

Published online 15 December 2015

Circular forms of RNA are much more abundant in platelets than previously thought, reports a new study.

Nadia El-Awady

Scientists in the UK and Kuwait probe novel forms of ribonucleic acid (RNA) to try and understand them more.

RNA transfers genetic code sequences from the DNA to ribosomes, which translate them to manufacture proteins required for the body’s cell processes. Recently, researchers have identified novel circular forms of RNA (circRNAs) that seem to be more stable and less vulnerable to degradation than their linear counterparts, making them excellent candidates as biomarkers. 

The scientists from multiple universities in the UK and the Kuwait Medical Genetics Centre studied how the stability of circRNAs in platelets, tiny circulating cell fragments important in coagulation, affects their numbers relative to linear RNAs. Platelets cannot produce new RNAs because they lack a nucleus. 

“Levels of circRNAs are massively increased in platelets relative to levels of linear RNAs coming from the same genes; up to around 3,500-fold in one instance. And for some genes it looks as if there is virtually no linear RNA in platelets at all,” says Michael Jackson from the Institute of Genetic Medicine at Newcastle University in the UK. 

The results suggest that degradation of linear RNA is extensive, that previous measurements of some linear RNA levels are inaccurate because they included measurements of circRNA, and that more sophisticated methods that target intact linear RNAs are needed for future analyses, says Jackson. 

Other studies had previously suggested that 50% of reported circRNAs are artefacts, but this study shows that they’re not. 


Alhasan, A. A. et al. Circular RNA enrichment in platelets is a signature of transcriptome degradation. Blood (2015).