Company: BLLN
Filing Date: 2025-10-17
Form Type: S-1/A
Source: 0001193125-25-242632
Chunk: 221

Company: BillionToOne, Inc.
Filing Date: 2025-10-17
Form: S-1/A
Chunk 221
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immunized pregnancies and detects key fetal RBC antigens, including D, C, c, E, K (Kell), and Fya (Duffy), helping to guide clinical decisions and reduce unnecessary monitoring. As the only commercially available test for fetal antigen screening in the United States, UNITY Fetal Antigen NIPT not only solves a previously unmet clinical need but has deepened our relationships with Maternal-Fetal Medicine (MFM) specialists.

| 61 |     | Rego, S., Balogun, O. A., Emanuel, K., Overcash, R., Gonzalez, J. M., Denomme, G. A., Hoskovec, J., King, H., Wilson, A., Wynn, J., & Moise, K. J. Jr. (2024). Cell-free DNA analysis for the determination of fetal 
 red blood cell antigen genotype in individuals with alloimmunized pregnancies. Obstetrics & Gynecology, 144(4), 436-443.                                                                                             |

| 62 |     | Wynn, J., Hoskovec, J., Carter, R., et al. (2023). “Performance of single-gene noninvasive prenatal testing for autosomal recessive conditions in a general population setting.” Prenatal Diagnosis, 
 43(10), 1344-1354.                                                                                                                                                                                   |

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Current Clinical Recommendation WEEK 10 Partner sample collected to determine antigen status. (assuming partner is available) WEEK 12 If partner is antigen positive, invasive diagnostic testing offered but frequently declined. WEEKS 12-13 Titers are monitored frequently via maternal blood draw. Regular middle cerebral arterial Doppler assessment may be recommended. WEEK 37 Baby likely to be delivered early. UNITY Fetal Antigen NIPT WEEK 9 Fetal Antigen NIPT ordered WEEK 10 Fetal antigen status provided as "detected" or "not detected" to guide pregnancy management. up to 65% of pregnancies are not at risk

UNITY Fetal Antigen NIPT’s clinical accuracy has been validated in multiple peer-reviewed publications, including a Scientific Reports study demonstrating 100%
concordance between test results and neonatal antigen status. UNITY Fetal Antigen NIPT offers 100% sensitivity and specificity while maintaining a no-call rate of <0.1%, ensuring highly reliable results.

In 2024, ACOG issued two clinical guideline updates, referencing UNITY Fetal RhD NIPT and UNITY Fetal Ant