Background: Thymidylate Synthase (TS) is an important target for folic acid inhibitors
such as pemetrexed, which has considerable effects on the first-line treatment, second-line
treatment and maintenance therapy for patients with late-stage Non-Small Cell Lung Cancer
(NSCLC). Therefore, detecting mutations in the TYMS gene encoding TS is critical in clinical
applications. With the development of Next-Generation Sequencing (NGS) technology, the
accuracy of TYMS mutation detection is getting higher and higher. However, traditional methods
suffer from false positives and false-negatives caused by factors like limited sequencing read
length and sequencing errors.
Objective: A method was needed to overcome the short sequencing read length and sequencing
errors of NGS to make the detection of TYMS more accurate.
Methods: In this study, we developed a novel method based on "Paired Seed Sequence Distance”
(PSSD) to detect the Variable Number of Tandem Repeat (VNTR) mutation for TYMS.
Results: With the 121 samples validated by sanger, the consistency rate of PSSD method was
85.95% (104/121), higher than the strict matching method (78.51% (95/121)). The consistency rate
of the two methods was 89.26% (108/121). We also found that the PSSD method was significantly
better than the strict matching method, especially in the 4R typing.
Conclusion: Our method not only improves the detection rate and accuracy of TYMS VNTR
mutations but also avoids problems caused by sequencing errors and limited sequencing length.
This method provides a new solution for similar polymorphism analyses and other sequencing