How do you define difficult genes? September 13, 2019 16:42 Updated Genes with high / low GC, long repeats or secondary structure that makes the gene difficult to perform PCR or sequencing. Related articles How can I check the quality of the gene you synthesized? Do you offer rush order service? What is the biggest gene you can synthesize? How should I amplify plasmid DNA from a bacstab or glycerol stock received from GenScript? How do you typically transform plasmids?