Dr. Lansdorp and his team. Pictured left to right: Tiffany Leung, Trang Nguyen, Dr. Peter Lansdorp, Yanni Wang, and Daniel Chan (missing: Mianne Lee, Geraldine Aubert and Amy Yu).
For years, scientists have been able to read pieces of DNA, but understanding how those pieces all fit together has been a challenge. A powerful method called Strand‑seq, developed in the laboratory of Dr. Peter Lansdorp is helping to change that. Dr. Lansdorp, a distinguished scientist of the Terry Fox Laboratory at the BC Cancer Research Institute and his former student Vincent Hanlon, just published a paper in Nature Genetics, in which the development and applications of the Strand-seq method are clearly explained and illustrated.
Strand-seq is a short-read DNA-sequencing technique that uses single cells to bring unique directional DNA sequence information to multi-technology genomic analyses. It allows researchers to study DNA one chromosome at a time, showing how genetic information from both parents is arranged across the entire genome.
“Strand-seq has a great advantage over other methods to connect DNA sequences inherited from each parent across large regions of repetitive DNA along entire chromosomes. It is also a great tool to discover inversions, segments of DNA with an orientation that can vary between people," said Dr. Lansdorp.
A main benefit of Strand-seq is its ability to identify large structural variants, including probable germline variants that occur in all cells, or clonal variants that occur in just a few cells. When combined with new long‑read sequencing technologies, Strand-seq creates a much more complete and accurate picture of a person's DNA than was previously possible. This approach helps identify genetic changes that are easy to miss with standard tests and can even show whether specific variants were inherited from a person's mother or father. That level of detail is especially important for understanding inherited disease risk and guiding treatment decisions. Indeed, Strand-seq is a key enabler for parent-of-origin research, and the Lansdorp team is actively collaborating with scientists Dr. Intan Schrader and Dr. Steven Jones and their teams to advance this work.
The advances have important implications for cancer research, treatment, and prevention. Cancer is often driven by large structural changes in DNA that are difficult to detect using standard methods. By identifying these changes, even when they appear in only a small number of cells, Strand‑seq offers new opportunities to better understand how cancers begin, evolve and respond to treatment. Over time, this could support earlier detection, improved risk assessment, and more personalized treatment approaches. As long‑read sequencing and Strand‑seq continue to scale and move toward clinical use, they have the potential to replace many traditional genetic tests. Fully mapped personal genomes could become a foundational part of an individual's medical record.
Together, these advances bring us closer to truly personalized medicine that reflects each person's unique genetic blueprint.