Clonal lineage identification

Immune repertoire analysis results report B cell clonal linages. This view is available for both the Oncomine™ BCR IGH‑LR Assay and Oncomine™ BCR IGH‑SR Assay. The Oncomine™ BCR IGH‑LR Assay provides additional information on the isotype representation among lineage members.

A B cell clonal lineage represents a set of B cells that are related by descent, arising from the same VDJ rearrangement event. B cells in a clonal lineage can differ at the sequence level owing to somatic hypermutation or isotype switching. Members of a clonal lineage are more likely to have a shared antigen specificity than members of different clonal lineages. Analysis of patterns of somatic hypermutation within clonal lineages can be used to infer patterns of isotype switching and identify IGH residues important for antigen recognition. For these reasons, the clonal lineage is a fundamental unit of B cell repertoire analysis. Ion Reporter™ Software automatically groups B cell clones into clonal lineages such that lineage members:

• Have the same variable and joining genes, excluding allele information.

• Have CDR3 regions of the same nucleotide sequence length.

• Have ≥85% CDR3 region sequence homology with one another.

Each clone is assigned a Lineage ID. The ordering of the Lineage ID reflects the abundance ranking of the clonal lineage, which is calculated by determining the sum of the frequencies of all members of the clonal lineage. Lineage 1 corresponds to the most abundant lineage, followed by Lineage 2, until the least abundant lineage is reached.

The Lineage ID is displayed in the leftmost column of the clone summary and lineage summary views.