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Background: Massively-parallel-sequencing, coupled with sample multiplexing, has made genetic tests broadly affordable. However, intractable index mis-assignments (commonly exceeds 1%) were repeatedly reported on some widely used sequencing platforms. Results: Here, we investigated this quality issue on BGI sequencers using three library preparation methods: whole genome sequencing (WGS) with PCR, PCR-free WGS, and two-step targeted PCR. BGI's sequencers utilize a unique DNA nanoball (DNB) technology which uses rolling circle replication for DNA-nanoball preparation; this linear amplification is PCR free and can avoid error accumulation. We demonstrated that single index mis-assignment from free indexed oligos occurs at a rate of one in 36 million reads, suggesting virtually no index hopping during DNB creation and arraying. Furthermore, the DNB-based NGS libraries have achieved an unprecedentedly low sample-to-sample mis-assignment rate of 0.0001 to 0.0004% under recommended procedures. Conclusions: Single indexing with DNB technology provides a simple but effective method for sensitive genetic assays with large sample numbers.
Li, Q., Zhao, X., Zhang, W., Wang, L., Wang, J., Xu, D., … Jiang, Y. (2019). Reliable multiplex sequencing with rare index mis-assignment on DNB-based NGS platform. BMC Genomics, 20(1). https://doi.org/10.1186/s12864-019-5569-5