You will be shown biomedical passages and your task is to the answer the provided question. Provide a concise and accurate response and do not include any additional text in the response other than the answer.

Question: What is a circRNA?

Context: Circular RNAs (circRNAs) are a new class of non-coding RNA with a stable structure formed by special loop splicing.
Circular RNAs (circRNA) have been reported as regulators involved in hepatocellular carcinoma (HCC), but their mechanism of activity remains unknown.
Recent technological advances in RNA sequencing and analysis have allowed an increasingly thorough investigation of a previously unexplored class of transcripts, circular (circ)RNAs. Accumulating evidence suggests that circRNAs have unique functions which often rely on their association with microRNAs and RNA-binding proteins. Through these interactions, circRNAs have been implicated in major cellular processes and hence in the pathophysiology of a range of diseases.
Circular RNAs (circRNAs) are a new class of non-coding RNA with a stable structure formed by special loop splicing.