What is hybridization capture?
Hybridization capture, also called target enrichment, is a method of targeted next generation sequencing (other methods of targeted sequencing can include
the use of amplicons or molecular inversion probes). Before hybridization capture is performed, DNA samples are converted into sequencing libraries. To create libraries,
the DNA is randomly sheared into smaller fragments by mechanical or enzymatic methods, and sequencing adapters are added. Depending on the library design, PCR amplification may be required.
Regions of interest within the library are then captured using long, biotinylated oligonucleotide baits (probes). Biotinylated baits/probes are designed to hybridize to regions of interest (e.g., exome, known genes related to cancer or a metabolic pathway).
After hybridization of baits to the fragmented DNA, streptavidin is used to separate the bait:targeted fragment complex from other fragments that are not bound to baits. Baits can be arranged in different ways to sequence regions of interest. For
- Tiling baits allows regions that are sequenced to align end to end.
- Overlapping baits permits extra sequencing to occur at the ends of baits to ensure that no part of the sequence is missed.
Baits can also be positioned to overcome challenging motifs such as repetitive sequences. Because the DNA has been randomly sheared during library preparation, captured fragments are overlapping and unique.