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. 2014 Jan 21;2(2):186–200. doi: 10.1002/mgg3.62

Figure 2.

Figure 2

Histograms of signal distributions from FP and TP variants. (A) Distribution from an overcall of a homopolymeric stretch of 6-mer As. The stretch was called containing 7-mer As in 23% of the reads. A single peak around 6-mer with long tails indicates a false-positive call. (B) Signal distribution from a true call (c.680_683del in MSH2) leading to the sequence change GAAAGAAAAAAAG→GAAAAAAAG. This distribution shows strong evidence for both 3-mer and 7-mer. Dual peaks with distributions for both forward and reverse reads centered on the values 3-mer and 7-mer indicate a true-positive variant. (C) Signal distribution from an overcall of a homopolymeric stretch of 6-mer Ts. The stretch was called containing 7-mer Ts in 24% of the reads. A single peak around 6-mer Ts with long tails indicates a false-positive call. (D) Signal distribution from a true-positive call (c.*85T>A in MSH6) of a variant located between two homopolymeric regions (TTTTTTAAAAA). This distribution indicates both 5-mer and 6-mer Ts for this homopolymeric region. Note that histogram (A and B) are made up of more reads than histogram (C and D). Higher coverage gives nicer distributions and facilitate interpretation.