**1. Introduction**

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MicroRNAs (miRNAs) participate in several biological processes, including development, differentiation, apoptosis, and proliferation (**1, 2**) through imperfect pairing with target messenger RNAs (mRNAs) of protein-coding genes and transcriptional or posttranscriptional regulation of their expression (**3, 4**). Approaches to miRNA detection, such as parallel sequencing technologies may replace conventional sequencing (**5**). The GS 454 technology can produce a similar number of longer (100–150-nucleotides (nt)) sequence reads in a single analysis run, with the advantage that this method can derive the complete sequence of the mature miRNA. Moreover, recent studies on miRNA profiling performed with cloning techniques suggest that sequencing methods are suitable for the detection of novel miRNAs, modifications, and precise compositions, and that cloning frequencies calculated by clone count analysis strongly correlate with the concentrations measured by Northern blotting, and are reproducible. The achievement of comprehensive profiling of miRNA in human diseases requires exhaustive qualitative and quantitative analyses. Here we show the techniques and the some of the results of the miRNA transcriptomes in the liver using sequencing. This serves as a critical step in clarifying the functional significance of specific miRNAs as they relate to liver diseases.
