Successful targeted sequencing requires uniform coverage across sequences. However, sequencing reads are often not distributed evenly over targeted areas. Truncated and/or hard-to-synthesize probes used for target capture often contribute to poor coverage uniformity. Target capture probes, therefore, benefit from quality control and normalization, which is generally not possible for the array-synthesized probes provided by most manufacturers. Thus, many probe pools and panels do not provide uniform coverage. IDT is uniquely positioned to synthesize target capture probes—xGen Lockdown Probes—that can provide uniform coverage.
We use a proprietary IDT Ultramer™ oligonucleotide synthesis process, which has the highest coupling efficiency in the industry (99.6%; Figure 1).
The high coupling rate allows us to synthesize long oligos (xGen Lockdown Probes are 60–120 bases long) with a high percentage of full-length product. Furthermore, because we synthesize each oligo individually, we can assess quality and normalize each oligo we manufacture, ensuring that each probe is represented in target capture pools. The presence of all probes at full length within a pool provides consistent end-to-end tiling across the target(s) and improves coverage uniformity (Figure 2).