Comprehensive Profiling of Circulating miRNAs
A range of platforms for miRNA screening were developed. In principle, three different methods are in use: microarray hybridization, amplification-based technologies and high-throughput sequencing. Circulating miRNAs can also be (semi) quantified using these technologies, although input requirements render some of the platforms unsuitable for larger clinical studies. Compared to longer transcripts, quantification of miRNAs requires specific modifications. Mature miRNAs have a small size and display relatively low abundance and unequal melting temperatures. Additionally, modifications of the detection methods that enable quantification of the mature miRNAs but not the primary and precursor miRNA as well as the discrimination of closely related miRNA families that exhibit high sequence similarity are essential. A detailed comparative study of the different platforms demonstrated significant variation in terms of reproducibility, sensitivity, accuracy and specificity and concluded that each method has its strengths and weaknesses (Mestdagh et al. 2014).