The approach directly assesses fetal risk from maternal blood, achieving 94.4% sensitivity while addressing gaps caused by incomplete partner carrier testing.
BillionToOne announced the publication of a multi-site study in The Green Journal evaluating the performance of cell-free DNA (cfDNA) testing for recessive conditions in a large, general-risk pregnancy population. The study provides evidence supporting the routine use of cfDNA fetal risk assessment in general-risk pregnancies, according to a press release from the company.
Conducted across nine US institutions, the prospective study evaluated 2,212 pregnant carriers where partner carrier status was unknown at the time of testing. Investigators assessed these carriers for cystic fibrosis, spinal muscular atrophy, and alpha- and beta-hemoglobinopathies. The research team collected outcomes for 98.6% of pregnancies that completed care at participating sites.
Clinical Performance and Sensitivity
The Unity Fetal Risk Screen demonstrated 94.4% sensitivity, 99.5% specificity, and a negative predictive value of more than 99.9%. According to the company, this approach identifies more affected pregnancies than traditional carrier screening, which typically classifies fewer than 50% of affected pregnancies as high-risk due to incomplete partner screening.
Traditional carrier screening depends on partner testing to determine fetal risk, but partner follow-up is often incomplete or unavailable due to logistical and financial barriers. The cfDNA approach assesses fetal risk directly from maternal blood rather than inferring it from parental genotypes.
“Multi-center studies with this level of outcome completeness are rare in prenatal screening,” says Eliza McElwee, MD, assistant professor in the college of medicine department of obstetrics and gynecology at Medical University of South Carolina, in a release. “These results provide clinicians with a much stronger evidence base for incorporating cfDNA fetal risk assessment into routine carrier screening, with data that are directly relevant to everyday clinical practice.”
Addressing Limitations in Partner Testing
The study also demonstrated consistent performance across a racially and ethnically diverse population, supporting access to prenatal genetic screening without the requirement for partner testing. The assay provides a personalized, quantitative fetal risk result as high as 9-in-10, compared to the maximum 1-in-4 risk offered by traditional screening when both partners are confirmed carriers.
“This publication shows that carrier screening with cfDNA fetal risk assessment performs reliably in the general-risk population, not just in a research setting,” says Haywood Brown, MD, chief medical officer, prenatal at BillionToOne, in a release. “For patients, that means a high-risk pregnancy is far less likely to be missed simply because a partner sample was never collected.”
The Unity Fetal Risk Screen uses proprietary Quantitative Counting Template technology to quantify disease-related DNA fragments with single base-pair resolution. The technology allows for the detection and quantification of genetic targets down to the single DNA molecule.
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