What defines difficult genomic regions, and can primers be designed to cover these regions?
Regions with high GC content (≥65%), polypurine (GA) runs and repeats are considered difficult. Any SNP present within eight bases of the 3’ end of the primer sequence will also decrease design and amplification success rate. We can design to these difficult regions. However, they will be considered “nonstandard assays.” Calculation of the overall success rate will not include nonstandard assays, and our specifications also do not apply to nonstandard assays.