Figure 3. Read Length Distribution.

The Oncomine cfDNA Lung panel amplifies 35 different amplicons, ranging in size between 80 and 139 base pairs. (A) Theoretical size distribution of the Oncomine cfDNA Lung panel. Amplicons with similar sizes were grouped for better visibility. (B) Observed amplicon sizes for sample S2. Colored bars represent the different extraction protocols. Compared to the theoretical size distribution, a group of short fragments representing unincorporated primers is visible. Comparing the different extraction methods, there is a marked difference concerning fragments with short read lengths. The libraries prepared from cfDNA extracted using the protocols from Stratec and Thermo present excess shorter reads (unincorporated primers) with a decrease in target specific reads.