BillionToOne Inc is a molecular diagnostics company. It offers a portfolio of ultrasensitive tests covering prenatal genetic testing, cancer therapy selection, and response monitoring, which are based on its Quantitative Counting Templates (QCT) molecular counting platform. The company's product portfolio comprises UNITY, a portfolio of prenatal testing products that can conduct fetal risk analysis without requiring a paternal sample; Northstar Select, a ultrasensitive liquid biopsy test that provides insights into appropriate therapies for stage III or IV cancer patients; and Northstar Response, a tissue-free, pan-cancer, liquid biopsy test that measures several genomic loci uniquely methylated in cancer to provide insight into dynamic changes in therapy response.