Hybridization of target regions can occur either on a solid surface (microarray) or in solution.
Array-based target enrichment
In an array-based hybrid capture, genomic DNA is first sheared into randomly sized fragments. Sequencer-specific adapters are then added via a PCR reaction. An immobilized probe is used to capture the targets in the fragmented library. Nonspecific hybrids are then washed away and hybridized probes are eluted. While array-based capture methods are efficient in enriching targets of interest, they have several limitations, such as cost, limitations to the number of samples and large sample requirements.
Solution-based target enrichment
Solution-based target enrichment systems are designed to overcome the limitations imposed by array-based capture methods. 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 magnetic beads and subsequently amplified and sequenced.
Roche Sequencing Solutions offers SeqCap® Enrichment Kits for DNA hybrid capture-based target enrichment.