Imbalance score for assay calls

The Imbalance score is a metric that provides a measurement of the strength of fusion calls that involve ALK, RET, or ROS1 driver genes.

Several metrics and found Imbalance values were investigated and are considered a strong predictor of true fusions calls. Other predictors for fusions that involve NTRK1 driver genes are continually investigated.

Imbalance values are reported in the 3'/5' Imbalance column. The Imbalance score for an assay applies to all fusion calls with the driver gene that is reported in the Genes (Exons) column.

An Imbalance value is calculated by subtracting the number of 5' reads from the number of 3' reads, and dividing the result by the sum of all EXPR_CONTROL reads:

  • (3' reads - 5' reads) / (sum of all EXPR_CONTROL reads)

    Note: The column heading "3'/5' Imbalance" in the Analysis Results table implies that the imbalance value is a direct ratio of the 3' and 5' reads. The value is not a direct ratio of 3' and 5' reads.

  • Imbalance values are interpreted as follows:

    • Higher Imbalance values (0.025 or greater) indicate a greater likelihood that the fusion is present in your sample.

    • Lower Imbalance values (either close to zero or negative) indicate a greater likelihood that the fusion is not present in your sample.

    Note: Imbalance values provide information that is supplementary to the detection calls of "Present" or "Absent". If a fusion call is "Absent", then we recommended that you check the imbalance value to see if there is supplemental evidence of the presence of a fusion.