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10x Genomics
Chromium Single Cell CNV

Barcoded BAMs

The cellranger-dna cnv pipeline outputs a single position-sorted and indexed BAM file. These files are primarily provided for use with a BAM visualization tool such as the Integrated Genome Viewer (IGV).

File Records Reference Description
possorted_bam.bam Reads User-specified reference Barcode-corrected reads aligned to the user-specified reference, sorted by reference position.

The following assumes basic familiarity with the BAM format. More details on the SAM/BAM standard are available online.

BAM Barcode Tags

Chromium cellular and molecular barcode information for each read is stored as TAG fields:

TagTypeDescription
CBZChromium cellular barcode sequence that is error-corrected and confirmed against a list of known-good barcode sequences.
CRZChromium cellular barcode sequence as reported by the sequencer.
CYZChromium cellular barcode read quality. Phred scores as reported by sequencer.
BCZSample index read.
QTZSample index read quality. Phred scores as reported by sequencer.
GPZGenome position. Note: this is an auxiliary tag used for the purpose of duplicate marking and is not intended for downstream use. We intend to deprecate this tag in subsequent versions.
MPZGenome position of mate-pair. Note: this is an auxiliary tag used for the purpose of duplicate marking and is not intended for downstream use. We intend to deprecate this tag in subsequent versions.

The cell barcode CB tag includes a suffix "-1" that labels the GEMs from a single channel and we call a GEM group.

AGAATGGTCTGCAT-1

Cell Ranger DNA currently only supports libraries generated from a single GEM run and so the suffix is always -1. It can either be left in place and treated as part of a unique barcode identifier, or explicitly parsed out to leave only the barcode sequence itself.