Carrier screening, a form of genetic testing, can identify pregnancies at risk for genetic conditions that may be treated before birth, offering a pathway to early intervention for diseases like fetal and neonatal alloimmune thrombocytopenia (FNAIT), according to results of a study presented recently at the SMFM Annual Pregnancy Meeting.
FNAIT is an immune-mediated condition not detected through genetic screening but similarly managed with prenatal monitoring and, in some cases, in utero therapy. Together, these approaches highlight how identifying risk during pregnancy can enable targeted fetal care.
“Carrier screening can identify pregnancies at risk for conditions with available or emerging IU [intrauterine] therapies,” explained the authors of this study.
Prenatal interventions for genetic conditions are rapidly expanding, including in utero transfusions for fetal anemia and experimental enzyme replacement therapies for lysosomal storage disorders.
In contrast, FNAIT arises when maternal antibodies attack fetal platelets and is typically managed with maternal treatments such as intravenous immunoglobulin, with intrauterine platelet transfusions reserved for severe cases. Despite these differences, both models rely on recognizing risk early enough to intervene.
Read more about treatment and care of FNAIT
In this retrospective study, researchers analyzed carrier screening results from 1,077,487 women aged 18 to 55 years tested at a US commercial laboratory between January 2021 and August 2024. Among the screened population, 97% were tested for at least one gene of interest, most frequently SMN1, CFTR and HBA1/2. A subset of 117,870 women, or 10.9% of the cohort, underwent screening for all 13 conditions associated with potential in utero therapies.
Among those fully screened, the likelihood of being a carrier for a condition with established in utero treatment or an active clinical trial was 1 in 24, or 4.3%. For conditions with investigational therapies, the carrier frequency was 1 in 16, or 6.5%. Although individual gene frequencies varied by self-reported race and ethnicity, the overall probability of carrying at least one relevant condition remained consistently high across groups.
While each genetic condition is rare on its own, their combined frequency suggests a broader opportunity for prenatal diagnosis and treatment. Unlike FNAIT, which is identified through immune risk rather than carrier status, these conditions can be flagged through screening before or early in pregnancy, potentially expanding access to specialized fetal therapies.
For patients, the findings underscore that carrier screening may offer more than risk awareness. It may open access to treatment options before birth, similar in intent to how FNAIT is proactively managed, though through different biological pathways and clinical strategies. Educating patients about both genetic and non-genetic prenatal risks may help families make informed decisions about screening and care, with the goal of improving outcomes for their babies.
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