Long non-coding and circular RNAs in osteoporosis: Translation to clinical practice.

Non-coding RNAs (ncRNAs) belong to a class of untranslated nucleic acids involved in regulation of gene expression. ncRNAs are categorized as small (<200 ribonucleotides in length), i.e., microRNAs (miRNAs), and long ncRNAs (lncRNAs) (200 to thousands of ribonucleotides in length) and circular RNAs (circRNAs). In contrast to miRNAs, the roles of lncRNAs in general and circRNAs in bone metabolism specifically are not well understood. As such, a comprehensive understanding of these RNA species in bone turnover could be of great value in the development of new diagnostic tools and therapeutic targets. Unfortunately, measurement of these unique RNAs lacks standardization, a component critical to clinical translation. This review examines the potential role of lncRNA and circRNA as bone biomarkers, the need for validated and standardized measurement and challenges thereof.