RARE DISEASE
Hemolytic disease due to fetomaternal alloimmunization
Hemolytic disease due to fetomaternal alloimmunization
Hemolytic disease due to fetomaternal alloimmunization
Synonyms: HDFN, Hemolytic disease of the fetus and newborn
Synonyms: HDFN, Hemolytic disease of the fetus and newborn
Synonyms: HDFN, Hemolytic disease of the fetus and newborn
Drug discovery
3
drugs
With orphan designations
Overview
Hemolytic disease due to fetomaternal alloimmunization occurs when maternal IgG antibodies target fetal red blood cell antigens (typically RhD, Kell, or Duffy), causing hemolysis, anemia, and hyperbilirubinemia. It arises from maternal sensitization via prior pregnancy, transfusion, or fetomaternal hemorrhage. Severe cases may lead to hydrops fetalis or kernicterus, but RhD immunoprophylaxis has significantly reduced incidence [1][4][8].
Burden
Perinatal mortality has declined from 50% to <5% with IUT and immunoprophylaxis [4][8].
Up to 30% of neonates require postnatal transfusions for anemia, with hydrops fetalis linked to 61% survival versus 96% in non-hydropic cases [2][12].
Non-RhD alloimmunization is rising proportionally, contributing to residual morbidity despite RhD prevention [6][9].
Therapies
Antenatal: Intrauterine transfusion (IUT) for fetal anemia detected via middle cerebral artery Doppler velocimetry [2][10], with 90% survival in non-hydropic fetuses [2].
Postnatal: Phototherapy, exchange transfusion, and IV immunoglobulin for hyperbilirubinemia; late anemia often requires transfusions [4][8][12].
Prevention: Anti-D immunoglobulin for RhD-negative mothers, but no prophylaxis exists for non-RhD antigens [3][5][9].
Categories: rare hematological diseases
Research Papers
722 drug discovery papers about Hemolytic disease due to fetomaternal alloimmunization, with 2 first-in-class and 9 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
722 drug discovery papers about Hemolytic disease due to fetomaternal alloimmunization, with 2 first-in-class and 9 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-04-25 | Rare antigen-negative red blood cells from pluripotent stem cells for precision transfusion medicine.
Blood bank identification of antibodies against high-prevalence antigens remains a challenge due to the scarcity of antigen-negative reagent red cells sourced from blood donors. The MAM antigen, encoded by EMP3, is one such antigen associated with red cell alloimmunization and hemolytic disease of the fetus and newborn. We used CRISPR-Cas9 gene editing to generate an EMP3 knockout (EMP3KO) induced pluripotent stem cell (iPSC) line from a type O, Rh null parent line, enabling production of rare MAM-negative red blood cells. Since a prior study suggested that loss of EMP3 may enhance erythroid proliferation, we hypothesized that EMP3KO could both yield a rare reagent cell and potentially improve erythroid expansion to support scalable production. Transcriptomic analysis allowed us to further investigate the effect of EMP3 loss in late erythroblasts. EMP3KO cells differentiated efficiently into erythroid cells, showing >95% CD235/CD71 co-expression and orthochromatic erythroblast morphology. Compared to unedited cells, no proliferative advantage was observed, contrasting with prior non-isogenic cell models. Agglutination assays confirmed complete loss of MAM antigen and demonstrated the diagnostic utility for identifying MAM antibodies. Transcriptomic profiling of EMP3KO erythroblasts revealed expression of key erythroid genes, as well as regulators of proliferation and heme metabolism, was comparable to the parent line. This study demonstrates that iPSC technology combined with gene editing can generate rare antigen-negative RBCs for immunohematology applications. Beyond MAM, this platform offers a strategy to create additional rare RBC phenotypes, advancing precision transfusion medicine and improving antibody identification against high-prevalence antigens.
2026-04-24 | Adverse perinatal outcomes indicative of RhD-mediated hemolytic disease of the fetus and newborn in Eastern Ethiopia: evidence of maternal health inequity in a multicenter cohort study.
Although hemolytic disease of the fetus and newborn (HDFN) has become rare in high-income countries, it remains a significant cause of perinatal death in low-and middle-income countries. Nonetheless, true epidemiological data in Africa are lacking. To obtain insight into the prevalence of anti-Rhesus D-mediated HDFN in Ethiopia, pregnancy outcomes were compared between RhD-negative and RhD-positive women. A multicenter facility-based retrospective cohort study was performed on 6796 women who gave birth (≥28 weeks of gestation) in 13 Ethiopian Obstetric Surveillance System hospitals from January to March 2024. Data were retrospectively collected from maternal and neonatal medical records from antenatal care to birth and neonatal registry. The composite adverse perinatal outcomes (APO) included stillbirth, neonatal loss, or Neonatal Intensive Care Unit admission. The likelihood of HDFN was based on clinical review by 3 experts blinded to the maternal blood group. In 6141 of 6796 women with known RhD status, 327 (5.3%) were RhD-negative. APO was seen in 13.3% women, and occurred twice as often in RhD-negative, as compared to RhD-positive women (aOR=2.3; 95% CI: 1.7-2.9). Clinical signs were highly suggestive of HDFN in 5.8% of RhD-negative women, as compared to 0.2% in RhD-positive women (P<.0001). Our study identifies that RhD-negative women experience a two-fold increased odds of APO, most likely due to HDFN. This highlights the need for strategies to address these maternal and child health inequities, including using anti-RhD immunoprophylaxis to prevent HDFN and screening for blood group antibodies to identify pregnancies at risk.
2026-04-13 | Routine transfusion of Rh(D)-positive RBCs to Rh(D)-negative patients designated as do not resuscitate conserves Rh(D)-negative red blood cell inventory.
A minority of blood donors are Rh(D)-negative, and Rh(D)-negative red blood cell (RBC) products are often overutilized. As such, Rh(D)-negative RBCs may be difficult to maintain in blood bank inventory. We changed our blood bank laboratory policy to approve non-alloimmunized Rh(D)-negative patients to receive Rh(D)-positive RBCs for routine transfusion under defined criteria. Those criteria included Rh(D)-negative males (all ages) and females (aged >50 years) who were designated as do not resuscitate (DNR), either with or without intubation, in the electronic medical record. From August 15, 2024 through August 15, 2025, a total of 204 Rh(D)-negative patients met the above criteria and were approved to receive routine Rh(D)-positive RBC transfusions. Within that group, 23 patients received Rh(D)-positive RBCs. The remaining patients either did not require transfusion or were issued Rh(D)-negative RBC units. Since implementing this practice, a total of 68 Rh(D)-negative units were conserved during this time frame. Notably, 28 of the 68 units (41%) were type O, Rh(D)-negative. Rh(D)-positive RBCs can be routinely given to non-alloimmunized Rh(D)-negative patients who are not at risk for developing hemolytic disease of the fetus and newborn (HDFN). By creating clear guidelines for the routine administration of Rh(D)-positive RBCs to patients who are not at risk for HDFN, the inventory of Rh(D)-negative RBC units can be directed to those patients who would most benefit from this limited resource.
2026-04-25 | Rare antigen-negative red blood cells from pluripotent stem cells for precision transfusion medicine.
Blood bank identification of antibodies against high-prevalence antigens remains a challenge due to the scarcity of antigen-negative reagent red cells sourced from blood donors. The MAM antigen, encoded by EMP3, is one such antigen associated with red cell alloimmunization and hemolytic disease of the fetus and newborn. We used CRISPR-Cas9 gene editing to generate an EMP3 knockout (EMP3KO) induced pluripotent stem cell (iPSC) line from a type O, Rh null parent line, enabling production of rare MAM-negative red blood cells. Since a prior study suggested that loss of EMP3 may enhance erythroid proliferation, we hypothesized that EMP3KO could both yield a rare reagent cell and potentially improve erythroid expansion to support scalable production. Transcriptomic analysis allowed us to further investigate the effect of EMP3 loss in late erythroblasts. EMP3KO cells differentiated efficiently into erythroid cells, showing >95% CD235/CD71 co-expression and orthochromatic erythroblast morphology. Compared to unedited cells, no proliferative advantage was observed, contrasting with prior non-isogenic cell models. Agglutination assays confirmed complete loss of MAM antigen and demonstrated the diagnostic utility for identifying MAM antibodies. Transcriptomic profiling of EMP3KO erythroblasts revealed expression of key erythroid genes, as well as regulators of proliferation and heme metabolism, was comparable to the parent line. This study demonstrates that iPSC technology combined with gene editing can generate rare antigen-negative RBCs for immunohematology applications. Beyond MAM, this platform offers a strategy to create additional rare RBC phenotypes, advancing precision transfusion medicine and improving antibody identification against high-prevalence antigens.
2026-04-24 | Adverse perinatal outcomes indicative of RhD-mediated hemolytic disease of the fetus and newborn in Eastern Ethiopia: evidence of maternal health inequity in a multicenter cohort study.
Although hemolytic disease of the fetus and newborn (HDFN) has become rare in high-income countries, it remains a significant cause of perinatal death in low-and middle-income countries. Nonetheless, true epidemiological data in Africa are lacking. To obtain insight into the prevalence of anti-Rhesus D-mediated HDFN in Ethiopia, pregnancy outcomes were compared between RhD-negative and RhD-positive women. A multicenter facility-based retrospective cohort study was performed on 6796 women who gave birth (≥28 weeks of gestation) in 13 Ethiopian Obstetric Surveillance System hospitals from January to March 2024. Data were retrospectively collected from maternal and neonatal medical records from antenatal care to birth and neonatal registry. The composite adverse perinatal outcomes (APO) included stillbirth, neonatal loss, or Neonatal Intensive Care Unit admission. The likelihood of HDFN was based on clinical review by 3 experts blinded to the maternal blood group. In 6141 of 6796 women with known RhD status, 327 (5.3%) were RhD-negative. APO was seen in 13.3% women, and occurred twice as often in RhD-negative, as compared to RhD-positive women (aOR=2.3; 95% CI: 1.7-2.9). Clinical signs were highly suggestive of HDFN in 5.8% of RhD-negative women, as compared to 0.2% in RhD-positive women (P<.0001). Our study identifies that RhD-negative women experience a two-fold increased odds of APO, most likely due to HDFN. This highlights the need for strategies to address these maternal and child health inequities, including using anti-RhD immunoprophylaxis to prevent HDFN and screening for blood group antibodies to identify pregnancies at risk.
2026-04-13 | Routine transfusion of Rh(D)-positive RBCs to Rh(D)-negative patients designated as do not resuscitate conserves Rh(D)-negative red blood cell inventory.
A minority of blood donors are Rh(D)-negative, and Rh(D)-negative red blood cell (RBC) products are often overutilized. As such, Rh(D)-negative RBCs may be difficult to maintain in blood bank inventory. We changed our blood bank laboratory policy to approve non-alloimmunized Rh(D)-negative patients to receive Rh(D)-positive RBCs for routine transfusion under defined criteria. Those criteria included Rh(D)-negative males (all ages) and females (aged >50 years) who were designated as do not resuscitate (DNR), either with or without intubation, in the electronic medical record. From August 15, 2024 through August 15, 2025, a total of 204 Rh(D)-negative patients met the above criteria and were approved to receive routine Rh(D)-positive RBC transfusions. Within that group, 23 patients received Rh(D)-positive RBCs. The remaining patients either did not require transfusion or were issued Rh(D)-negative RBC units. Since implementing this practice, a total of 68 Rh(D)-negative units were conserved during this time frame. Notably, 28 of the 68 units (41%) were type O, Rh(D)-negative. Rh(D)-positive RBCs can be routinely given to non-alloimmunized Rh(D)-negative patients who are not at risk for developing hemolytic disease of the fetus and newborn (HDFN). By creating clear guidelines for the routine administration of Rh(D)-positive RBCs to patients who are not at risk for HDFN, the inventory of Rh(D)-negative RBC units can be directed to those patients who would most benefit from this limited resource.
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Drug Discovery Landscape
3 orphan drug designations for Hemolytic disease due to fetomaternal alloimmunization.
3 orphan drug designations for Hemolytic disease due to fetomaternal alloimmunization.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
nipocalimab | antibodies | FDA | 2020-06-26 | — | Janssen Research & Development, LLC |
Anti-neonatal Fc receptor human monoclonal antibody | antibodies | EMA | 2019-10-17 | — | Janssen-Cilag International N.V. |
Trisaccharides A and B | small molecules | FDA | 1987-04-12 | — | Chembiomed, Ltd. |
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