David Tsao: One in eleven babies now screened by advanced genetic tests, BillionToOne’s MRD test for early cancer detection is imminent, and AI integration is revolutionizing healthcare | Y Combinator Startup Podcast

Revolutionary DNA test by BillionToOne could transform early cancer detection and prenatal screening in the US.

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Add us on Google by Editorial Team Apr. 6, 2026

Key takeaways

• Genetic testing has rapidly evolved, with one in eleven babies in the US now screened by tests unavailable a decade ago.
• BillionToOne is on the verge of launching a highly sensitive MRD test for early-stage cancer detection.
• The ability to detect DNA in blood samples has enabled diagnostics that were previously impossible.
• BillionToOne enhances prenatal genetic testing accuracy by adding synthetic DNA to patient samples.
• Noise reduction in data is crucial for detecting genetic conditions from maternal blood samples.
• BillionToOne’s sales strategy includes quick training for sales reps to engage directly with patients.
• The company initially faced challenges in gaining traction, with only one physician using their test two months post-launch.
• AI and computer vision have been integrated to streamline sample processing workflows.
• BillionToOne’s facility has the potential to expand testing capacity to nearly 2,000,000 tests annually.
• The core technology for detecting free-floating DNA is applicable to both prenatal genetics and cancer detection.
• The rapid evolution of genetic testing technology underscores its transformative potential in healthcare.
• Scaling testing capabilities is critical for meeting growing healthcare demands.

Guest intro

David Tsao is Co-Founder and CTO at BillionToOne, a biotech company valued at $4 billion that has developed a DNA molecular counting platform for prenatal and cancer detection. He holds a PhD in bioengineering from Rice University, where he was awarded a Nanobiology training fellowship, and earned his bachelor’s degree in Physics, cum laude, from Princeton University with minors in Biophysics and Engineering Management Systems. As the original inventor of BillionToOne’s core DNA molecular counting technology, Tsao has presented the company’s clinical trial results at national medical conferences and helped transform the company from a half lab bench into one of the most widely used prenatal testing platforms in the US.

The evolution of genetic testing

• One in eleven babies born in America this year will be screened by a genetic test that didn’t exist a decade ago

  — David Tsao

• The rapid development in genetic testing technology has significantly impacted prenatal care.
• BillionToOne’s advancements showcase the potential for innovation in medical diagnostics.

• By detecting this DNA we can develop diagnostics that have been impossible even a decade ago

  — David Tsao

• The ability to detect DNA in blood samples is a game-changer for diagnostics.
• These advancements highlight the importance of continuous innovation in healthcare.
• The integration of new technologies is essential for improving patient outcomes.
• The evolution of genetic testing reflects broader trends in personalized medicine.

Breakthroughs in cancer detection

• BillionToOne is close to launching an ultra-sensitive MRD test for early-stage cancer detection.

• We are maybe less than a year away from launching our ultra-sensitive MRD test for stage one two cancer patients

  — David Tsao

• Early detection of cancer significantly improves treatment outcomes.
• The MRD test represents a potential breakthrough in oncology diagnostics.
• This innovation underscores the importance of early-stage cancer detection.
• The technology used in prenatal testing is also applicable to cancer detection.

• Fundamentally there is nothing different about cell-free fetal DNA and cell-free tumor DNA

  — David Tsao

• The versatility of the technology highlights its potential across medical applications.

Enhancing prenatal genetic testing

• BillionToOne improves prenatal testing accuracy by adding synthetic DNA to samples.

• What we have done is to add a synthetic DNA into the patient sample that we get before any amplification happens

  — David Tsao

• This approach addresses the challenge of detecting rare fetal DNA in maternal blood.
• Noise reduction in data is crucial for accurate genetic testing.

• We were able to determine that if we could reduce the noise we would be able to detect conditions like sickle cell disease

  — David Tsao

• The innovation behind BillionToOne’s technology significantly enhances prenatal diagnostics.
• Accurate prenatal testing is essential for early detection of genetic conditions.
• The company’s approach showcases the potential for innovation in genetic testing.

Overcoming early-stage challenges

• BillionToOne initially struggled to gain traction, with only one physician using their test two months after launch.

• Two months after launch you still only have like basically one user

  — David Tsao

• The company employed a strategic sales approach to overcome initial challenges.

• I need you to hire in the next three weeks five additional sales reps

  — David Tsao

• Direct patient engagement was key to influencing physician adoption.
• The challenges faced highlight the difficulties of launching new medical tests.
• The strategic approach reflects the importance of adaptability in startup dynamics.
• Overcoming early-stage challenges is critical for long-term success in healthcare startups.

Integrating AI and technology in healthcare

• AI and computer vision were integrated to streamline sample processing workflows.

• We had to incorporate AI and computer vision to accelerate this

  — David Tsao

• The integration of technology addresses operational bottlenecks in laboratory processes.
• The project, “accessioning in sixty seconds,” showcases the potential of technology in healthcare.
• The use of AI highlights the importance of innovation in improving healthcare efficiency.
• Technology integration is essential for scaling healthcare operations.
• The advancements reflect broader trends in the digital transformation of healthcare.
• The potential to expand testing capacity underscores the importance of technology in meeting healthcare demands.

Scaling testing capabilities

• BillionToOne’s facility has the potential to expand testing capacity to nearly 2,000,000 tests annually.

• We believe that we can expand into close to 2,000,000 tests per year just using this facility

  — David Tsao

• Scaling is critical for meeting growing healthcare demands.
• The potential for expansion highlights the importance of infrastructure in healthcare.
• The ability to scale testing capabilities is essential for addressing public health needs.
• The facility’s potential reflects the importance of strategic planning in healthcare operations.
• Scaling efforts underscore the need for continuous innovation in healthcare.
• The expansion potential is a testament to the company’s growth and impact in the industry.

The versatility of core technology

• The same technology for detecting free-floating DNA applies to both prenatal and cancer detection.

• The same technology can be applied to both cell-free fetal DNA and cell-free tumor DNA

  — David Tsao

• This versatility highlights the potential for cross-disciplinary applications in medicine.
• The technology’s adaptability reflects its transformative potential in healthcare.
• The ability to apply the same technology across different fields underscores its significance.
• The versatility of the technology is a key strength of BillionToOne’s approach.
• The potential for broad application highlights the importance of innovation in medical technology.
• The technology’s adaptability is critical for addressing diverse healthcare challenges.

Disclosure: This article was edited by Editorial Team. For more information on how we create and review content, see our Editorial Policy.