Sequencing is a process of recognition of DNA/RNA code, writing down the chain of nucleotides. The first human genome sequencing project took about 14 years and was finished in 2003. Nowadays the technology has developed to incredible speeds. It allows sequencing of the entire human genome in a few days.
The most popular sequencing technologies such as Illumina or IonTorrent use molecule amplification to increase the number of the DNA or RNA molecules in the sample. It creates certain bias for future processing. The accuracy in counting the number of types of molecules and their proportions has critical value for certain applications such as prenatal diagnostics of trisomy or quantitative gene expression. To the present moment (beginning of 2018) there are only three companies in the world manufacturing high speed sequencers, which do not require molecule amplification. The technology is called single molecule NGS (next generation sequencing), and the companies are Oxford Nanopore, PacBio и SeqLL (former Helicos).
SeqLL sequencers produce large numbers of reads of relatively short DNA/RNA fragments. It makes them a perfect tool for quantification of various types of molecules. Elimination of the intermediate amplification stage allows SeqLL platform to measure the parameters, which could be missed by other manufacturers. SeqLL technology is ideal for prenatal diagnostics, search for the RNA biomarkers, direct sequencing of transcripts with poly-A ends (DRS), and other similar applications.