Hybridization of target regions can occur either on a solid surface (microarray) or in solution. While both methods have their own advantages, solution-based target enrichment overcomes the shortcomings of array-based method, such as cost, limitations to the number of samples and large sample requirements, while retaining its advantages. This method is also easily scalable and can be easily automated.
In the solution-based method, genomic DNA is first sheared into randomly sized fragments with mechanical or enzymatic fragmentation. Sequencer-specific adapters carrying sample specific barcode sequences are then added via a ligation reaction. A pool of biotinylated oligonucleotide probes targeting the desired genes, exons, and/or other genomic regions of interest is added to adapter-ligated DNA in solution for hybridization with targeted regions of interest. The hybridized probes are then captured and purified by streptavidin magnetic beads and subsequently amplified and sequenced.
Roche Sequencing Solutions offers SeqCap® probes for DNA hybrid capture-based target enrichment. The SeqCap probes are solution-based, designed to be specific for the target regions of interest and ready to hybridize to a sequencing library in order to enrich for targets of interest.