来自deeptools的解释(https://deeptools.readthedocs.io/en/develop/content/tools/computeGCBias.html)In reality, the DNA polymerases used for PCR-based amplifications during the library preparation of the sequencing protocols prefer GC-rich regions. This will influence the outcome of the sequencing as there will be more reads for GC-rich regions just because of the DNA polymerase’s preference.
来自文章:DNA polymerase preference determines PCR priming efficiency(https://www.ncbi.nlm.nih.gov/pubmed/24479830)PCR is known to introduce biases, especially during multiplex reactions. DNA polymerase as the primary source of bias, particularly initiation of polymerization on the template strand. Preferentially amplified sequence motifs at the 3’ end of the primer were identified. These motifs demonstrated a marked GC-rich bias pattern.