Diagnostics · Prenatal screening and liquid biopsy
BillionToOne
A Menlo Park laboratory that counts individual DNA molecules in blood, first to tell a pregnant patient whether her fetus is at risk for a recessive disease, now to read tumors. It went public in November 2025 and sells nothing the FDA has reviewed.
Counting, not averaging
From about nine weeks of pregnancy, a maternal blood sample carries fragments of DNA shed by the placenta, mixed into a much larger pool of the mother’s own. Conventional screening reads that pool in bulk and asks a coarse question: is there too much chromosome 21 in here?
The harder question is about a single letter. Cystic fibrosis, sickle cell disease and spinal muscular atrophy are not extra chromosomes. They are one base pair out of three billion, inherited twice. To see that in a blood tube you cannot average. You have to count.
BillionToOne’s patented Quantitative Counting Templates are the answer, described in its filings as the only multiplex method that counts DNA molecules one at a time. The founders put the ambition into the prospectus itself.
The missing partner
Carrier screening has a practical failure mode. A pregnant patient is told she carries a cystic fibrosis variant, and the next step is to test the father. In more than half of pregnancies in some studies, that second sample never arrives. The couple is left with a carrier result and no fetal risk number.
UNITY was built for that gap. It returns a fetal risk estimate from the pregnant patient’s blood alone, for aneuploidies and for a panel of recessive conditions that reached 14 in May 2025 and 130 genes in August 2026. The company added fetal antigen testing, then in May 2026 a confirmation assay built on intact fetal cells rather than fragments.
Two roommates from Princeton
Oguzhan Atay and David Tsao met at a summer science program and later roomed together at Princeton, according to HOF Capital, an early investor. Atay took a PhD in biology at Stanford, Tsao a PhD in bioengineering at Rice.
The first federal money was small and specific: a $224,227 NIH grant in 2018, with Tsao as principal investigator, for a non-invasive prenatal test for sickle cell disease. In the prospectus Atay describes collecting the first specimens in Turkey and running the first clinical studies in India, where beta thalassemia is common.
From half a bench to the Nasdaq
UNITY launched in 2019 and the millionth test ran in March 2025. Revenue went from $152.6 million in 2024 to $305.1 million in 2025, and the company turned an operating profit. It filed to go public on October 7, 2025, priced 4.55 million shares at $60 on November 5, above a marketed range of $49 to $55, and opened at $100 the next morning. Reuters put the value at $4.4 billion on the first day.
Oncology followed. Northstar Select, a ctDNA panel for therapy selection, won Medicare coverage through the MolDX program effective February 14, 2025, and oncology revenue went from $2.9 million in 2024 to $25.0 million in 2025.
What is proven, and what is still claimed
| Evidence | What the record shows | Source type |
|---|---|---|
| FDA device records | No 510(k) and no PMA on file. The S-1 states that every test the company offers is a laboratory developed test, that its laboratories are regulated under CLIA and voluntarily accredited by the College of American Pathologists, and that its products are not subject to FDA approval requirements. | Public record |
| FDA safety communication | On April 19, 2022 the FDA warned about false results from genetic non-invasive prenatal screening tests. The warning applies to the category, not to one laboratory, and it named positive predictive value as the weak point. | Public record |
| Prospective performance | Obstetrics and Gynecology, August 2026: 2,403 cell free DNA results in 2,212 pregnant carriers at nine US sites, outcomes known for 98.6%. Sensitivity 94.4%, specificity 99.5%, negative predictive value 99.9%, positive predictive value 58.6%. | Public record |
| Who writes the evidence | The validation and outcomes papers for UNITY and Northstar list company employees among the authors, several with BillionToOne email addresses, alongside clinical sites. | Public record |
| Society guidance | ACOG endorsed SMFM Consult Series #74 in November 2025. It covers trisomies 21, 18 and 13, sex chromosome aneuploidies and microdeletions. It sets no recommendation for cell free DNA screening of recessive single gene conditions. | Public record |
| Published case report | AJP Reports, 2026: a couple both carrying CFTR F508del received a UNITY result of 1 in 51, reported as decreased risk. A competing test returned 92 in 100. Amniocentesis confirmed an affected fetus. | Independent |
| The company’s reply | Two BillionToOne authors answered in the same journal that one discordant result among hundreds of thousands of tests does not move population level estimates, and that the competing assay had no published validation. | Company-stated |
| A second critique | A separate letter argues the four category clinical report does not line up with the two category thresholds used in the published validation studies, so the same 1 in 51 result would have been scored high risk in those papers. | Independent |
| Oncology validation | Journal of Liquid Biopsy, September 2025: a prospective head to head study in 182 patients against six commercial assays, reporting 51% more pathogenic variants and indels. | Public record |
| Registered trials | ADVANCE (NCT07643896), the company’s observational circulating fetal cell study, started January 10, 2026 with 1,000 participants planned. | Public record |
Read plainly: the aneuploidy half of UNITY sits inside a category professional societies have endorsed, and the recessive condition half, which is what makes the product different, sits outside it. The company has answered that gap with volume and with a large prospective study, and that study is real evidence. It is also evidence the company helped write, in a field where the sharpest published criticism has come from clinicians with no stake in either laboratory.
What to watch
- Whether SMFM, ACOG or ACMG issue guidance on single gene cell free DNA screening, and what they say about risk thresholds and reporting categories.
- Whether validation data appear from authors with no company affiliation.
- Results from ADVANCE, and the evidence behind Unity Confirm, reported at launch on 16 validation samples.
- The 130 gene panel launched in August 2026. A wider panel raises both the conditions screened and the absolute number of false positives.
- Whether oncology, at $13.7 million in the second quarter of 2026, grows fast enough to matter next to prenatal.
In their words
“What is the most challenging, most impactful global healthcare problem that physics allows us to solve, but that no one else will tackle?”
Oguzhan Atay, co-founder and CEO, letter in the Form S-1, 2025 · Company filing
“It was more difficult to raise the initial $300,000 than the $300,000,000 that followed it.”
Oguzhan Atay, letter in the Form S-1, 2025 · Company filing
“Within the confines of the government shutdown, you can only upsize it 20%, so we took it up 20% just to give our long term public investors enough to start their positions”
Oguzhan Atay to Reuters, November 6, 2025 · Interview
“While health care providers widely use NIPS tests, none have yet been authorized, cleared, or approved by the FDA.”
FDA safety communication, April 19, 2022 · Public record
“These tests are not currently standard of care and are not yet recommended by any obstetric or genetics professional societies.”
Case report on discrepant single gene prenatal results, AJP Reports, 2026 · Peer reviewed
“Conversely, the false reassurance from the first sgNIPT may have deterred her from pursuing CVS at an earlier gestational age.”
Same case report, AJP Reports, 2026 · Peer reviewed
“A single discordant result in one patient out of hundreds of thousands who have been tested neither contradicts nor meaningfully modifies these population-level estimates.”
Julia Wynn and Jennifer Hoskovec, BillionToOne, AJP Reports, 2026 · Company-stated
“In other words, different metrics are used in clinical reporting and validation studies.”
Laura G. Hendon, University of Mississippi Medical Center, AJP Reports, 2026 · Peer reviewed
Related companies
Sources
- Public recordBillionToOne, Inc. Form S-1
- Public recordGenetic Non-Invasive Prenatal Screening Tests May Have False Results
- Public recordA Prospective, Multi-Site Study of Performance of Cell-Free DNA Testing for Recessive Conditions
- Peer reviewedDiscrepant Results on Two Different Single Gene Non-invasive Prenatal Tests for Cystic Fibrosis
- Company-statedImportant Limitations on the Conclusions of that case report
- Peer reviewedAlignment between Published Performance Metrics and Clinical Reporting in sgNIPT
- Peer reviewedFalse reassurance following single gene non-invasive prenatal testing for cystic fibrosis
- Company-statedResponse to Zemanick et al.
- Public recordScreening for Fetal Chromosomal Abnormalities, endorsing SMFM Consult Series #74
- Public recordValidation of a liquid biopsy assay with increased sensitivity
- Public recordNIH RePORTER 1R43HL144322-01
- Public recordClinicalTrials.gov NCT07643896, NCT07096362, NCT05733689
- IndependentBillionToOne valued at $4.4 billion in blockbuster Nasdaq debut
- IndependentDNA test maker BillionToOne raises $314M in IPO
- IndependentUnity Confirm fetal cell-based test launches
- IndependentWhy We Invested in BillionToOne
- CompanyFourth Quarter and Full Year 2025 Results
- CompanySecond Quarter 2026 Results
- CompanyMedicare Coverage for Northstar Select
- Company1 Million UNITY Tests
Profile researched and written by Healthcare Discovery. Last updated September 29, 2026.
