NimbleGen Sequence Capture arrays are suitable for targeted sequencing of any size, from small target regions like 250KB (Figure 1) to large regions as large as 30MB (Table 1). All human designs utilize the empirically optimized Sequence Capture design algorithm to ensure highly uniform capture. For example, a 250KB contiguous region, representing a typical GWAS locus, is captured with high specificity and uniformity (Figure 1). Note that small repetitive regions where no probes
were selected can still be covered by sequencing, due to efficient capture from neighboring probes and with the advantage of long reads from the Genome Sequencer FLX Titanium Series (red boxes in Figure 1).
Table 1. The ENCODE pilot regions (~30Mb) are captured using 2.1M arrays and sequenced. The target regions consist of ~ 50 individual contigs of ~ 500kb each
Figure 1. High-Performance Targeted Resequencing in a 250kb Target Region.
Roche offers a seamless workflow combining NimbleGen Sequence Capture Arrays and the high throughput sequencing of the Genome Sequencer FLX System from 454 Life Sciences. This complete solution of kits, arrays and instruments are specifically designed to optimize the workflow, reduce processing time, minimize costs, and enhance data quality. Furthermore, the GS Reference Mapper software from 454 Life Sciences enables researchers to easily identify variants like SNPs and indels from the final data output without complicated bioinformatics infrastructure (Table 2)
Table 2. Sequence Capture Performance on a 250 kb contiguous region and a 1 Mb contiguous region in the human genome. Data shown are from 1 of the 4 independent experiments for each region. A HapMap sample is used in the study and SNP calls were generated by the GS Reference Mapper software.
An example of discovering causative mutations, the mouse Kit locus (~200KB) from 5 non-complementing Kit mutants is shown in Figure 2. These alleles include one known allele W-41J, and four unknown alleles, W-20J, W-39J, W-40J and W-73J. The known mutation from W-41J was confirmed in this experiment, and the data analysis successfully identified a non-synonymous coding mutation for each of the 4 unknown alleles. (D’Ascenzo et al, Mamm. Genome, 2009, 20:424–436)
Figure 2. Mutation discovery in the mouse KIT Locus using Sequence Capture and 454 Sequencing.