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Molecular Identifiers

The Accel-NGS® 2S MID Indexing Kits have been designed, optimized, and validated for use with Accel-NGS 2S DNA Library Kits on Illumina® platforms, and aid in low frequency variant detection, as well as accurate de-duplication of single read sequencing and sequencing from samples with non-random fragmentation. Get the most out of your NGS sequencing data with this powerful tool.


Accel-NGS 2S Hyb DNA Library Kit
Accel-NGS 2S Plus DNA Library Kit

The Swift advantage:
  • Improve detection of low frequency alleles
  • Identify unique library molecules
  • Retain more sequencing data
  • Designed for exome sequencing
  • Compatible with circulating, cell-free DNA

The Structure of Swift MID Libraries


The Swift MID adapter utilizes a strand-specific 9 base random N sequence on the P5 adapter (index 2 position). This is paired with a standard low throughput P7 adapter, containing a 6 base single index (index 1 position) for multiplexed sequencing.

Identify Unique Library Molecules with MIDs

The Accel-NGS 2S MID Indexing Kits utilize an MID-containing P5 adapter in place of a standard P5 adapter during the Ligation II Step of the protocol. The 9 base random sequence of the MID uniquely labels library molecules in a strand-specific manner, which enables accurate de-duplication of your sequencing data.

Accel-NGS 2S MID Workflow


Supported DNA Sequencing Applications

  • Whole exome sequencing (WES)
  • Deep targeted sequencing
  • Cell-free DNA sequencing
  • Single-end sequencing, such as ChIP-Seq

Accel-NGS 2S MID Indexing Kits are compatible with Accel-NGS 2S DNA Library Kits, to enable a variety of applications. The Accel-NGS 2S Plus Kit can be used with MIDs to ensure accurate de-duplication of ChIP-Seq samples sequenced with single end reads, and cfDNA samples with non-random fragmentation. The Accel-NGS 2S Hyb Kit can be used with MIDs to ensure accurate identification of low frequency variants in exome data.

Retain More Data with Accel-NGS 2S MIDs

The data below demonstrate the performance of Accel-NGS 2S DNA Library Kits with molecular identifiers. A 9 base random N sequence MID has 262,144 theoretical MID sequence combinations. Both PCR-free and amplified 2S libraries attain close to theoretical representation of MID combinations with high copy uniformity. This powerful tool enables retention of fragment duplicate reads that would otherwise be discarded by traditional library preparations and bioinformatic analyses. For ChIP-Seq applications, this results in sharper, cleaner peaks and higher confidence peak calls.

Diverse and Even MID Representation


Accel-NGS 2S libraries were constructed with 2S MID Indexing Kits either PCR-free or with 9 cycles of amplification and sequenced on a MiSeq. Copy uniformity is the percentage of MIDs that are within 20% of the average MID copy number.

Generate Sharper ChIP-Seq Peaks with Accel-NGS 2S MIDs


Accel-NGS 2S libraries were constructed with standard or MID Indexing Kits and CTCF ChIP DNA from 4.5 million HepG2 cells. ENCODE CTCF ChIP-Seq data from 20 million cells is shown at the bottom for reference. Data generated by Active Motif.

To request sequencing data files (FASTQ, BAM, etc.) for the Accel-NGS 2S MID libraries, please email [email protected].