How I use noninvasive prenatal testing for red blood cell and platelet antigens

Abstract Alloimmunization during pregnancy occurs when a mother produces antibodies against fetal antigens, leading to complications like hemolytic disease of the fetus and newborn (HDFN) and fetal and neonatal alloimmune thrombocytopenia (FNAIT). HDFN involves destruction of fetal red blood cells, potentially causing severe anemia, hydrops fetalis, and fetal death. FNAIT affects fetal platelets and possibly endothelial cells, resulting in risk of intracranial hemorrhage and brain damage. Traditional invasive methods for fetal antigen genotyping, like amniocentesis, carried miscarriage risks. The discovery of cell-free fetal DNA (cff-DNA) in maternal plasma enabled safe, noninvasive prenatal testing (NIPT). Initially used for Rhesus antigen D blood group typing, NIPT now covers various blood group antigens. Advances in technology have further enhanced the accuracy of NIPT. Despite challenges such as low cff-DNA fractions and complex genetic variations, NIPT has become essential in managing alloimmunized pregnancies. In NIPT it is important to prevent both false-positive results and false-negative results. Particularly in the coming decades, more possibilities for personalized antenatal treatment for HDFN and FNAIT cases will become apparent and accurate NIPT blood group antigen typing results are crucial for guiding clinical decisions. In this paper we describe this journey and provide practical tools for the clinic.