Retrospective analysis of HDFN due to ABO incompatibility in a single institution over 6 years

A Description of IVIG Use in Term Neonates with ABO Incompatibility

OBJECTIVE

 This study aimed to determine if treatment with IVIG of neonates with ABO incompatibility (without Rh incompatibility) results in decreased number of packed red blood cell (pRBC) transfusions and phototherapy use.

STUDY DESIGN

 An Institutional Review Board (IRB)-approved, single-institution retrospective study was conducted. Neonates ≥38 weeks' gestational age born between January 1, 2007, and December 31, 2016, with ABO incompatibility were included. The comparison among groups was performed using chi-square and Fisher's exact tests for categorical variables; continuous variables were assessed by Kruskal-Wallis test.

RESULTS

 Six hundred and sixty-eight neonates with ABO incompatibility met inclusion criteria, 579 were included in the analyses. From these, 431 (74%) neonates had positive Direct Antiglobulin Test (DAT); 98 (17%) received IVIG and 352 (61%) received phototherapy. Thirty-six (6%) neonates received pRBC and 6 (1%) required exchange transfusions. Only 3 (0.5%) infants received pRBC transfusions postdischarge, by 3 months of age. Neonates requiring IVIG had lower initial hemoglobin (13.6 vs. 16.0 g/dL, p ≤ 0.0001) and higher bilirubin at start of phototherapy (9.1 vs. 8.1 mg/dL, p = 0.0064). From the 42 (7%) neonates who received simple and exchange transfusions, IVIG use was not associated with decreased use or number of transfusions (p = 0.5148 and 0.3333, respectively). Newborns with A+ and B+ blood types had comparable initial hemoglobin, DAT positivity, APGAR, and bilirubin. However, infants with B+ blood group were more likely (than A + ) to require phototherapy (p < 0.001), receive IVIG (p = 0.003), and need phototherapy for a longer duration (p = 0.001).

CONCLUSION

 The results of this large retrospective study reveal that giving IVIG to neonates with ABO incompatibility was associated with increased simple or exchange transfusions. Newborns with B+ blood type required more phototherapy and IVIG. Further studies are needed to better stratify neonates who would benefit from IVIG use in order to optimize treatment strategies and avoid unnecessary risks and adverse events.

KEY POINTS

· IVIG use not associated with decreased use of pRBC or exchanges.. · Phototherapy duration associated with increased IVIG and pRBC use.. · Newborns with B+ blood type had worse hemolytic anemia..

Direct antiglobulin test in the differential diagnosis of ABO hemolytic disease of the newborn: an important tool with high negative predictive value

BACKGROUND

Hemolysis due to ABO incompatibility is an important differential diagnosis in newborns presenting with jaundice. Clinical studies evaluating ABO hemolytic disease of fetus and newborn (ABO-HDFN) question the diagnostic value of the direct antiglobulin test (DAT) in this situation.

GOALS

To determine the clinical and laboratorial findings associated with the occurrence of ABO-HDFN and to evaluate the accuracy of DAT as a diagnostic tool.

METHODS

This was a nested case control study with a cohort of 4122 newborns. Clinical and immunohematological data were retrieved from medical files including clinical and laboratorial factors associated with ABO-HDFN. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of positive DAT were calculated.

RESULTS

Among the 4122 newborns, 44 had the diagnosis of ABO-HDFN. Positive DAT, group O mother and group A newborn were significantly associated with the occurrence of neonatal jaundice and this association persisted in a multivariable model (p-value <0.001). DAT presented 65.85 % sensitivity, 96.28 % specificity, 16.9 % PPV and 99.6 % NPV for the diagnosis of ABO-HDFN. There were no cases of positive DAT in cases other than O/A and O/B incompatibilities. The newborn hemoglobin was significantly lower in O/A incompatibility (p-value <0.001).

CONCLUSION

Positive DAT, mother of group O and newborn of group A are independent risk factors associated with ABO-HDFN. DAT exhibited high NPV for the diagnosis of this complication. Thus, performing DAT in newborns with O/A and O/B incompatibilities is a cost-effective strategy that can be applied as routine by blood banks.

Distribution of ABO and D antigen expression in Yogyakarta, Java Island: a pioneer large-scale study in Indonesia

OBJECTIVE

Here, we sought to report ABO and D antigen distribution in blood donors from Yogyakarta, Java Island, Indonesia. Phenotype data (ABO/D) from donors who donated blood between January 1, 2018, and December 31, 2023, at the Yogyakarta Blood Donor Unit were extracted from the blood donor registry, and phenotype frequency was calculated subsequently.

RESULTS

In the 245,307 blood donors collected over six years, ABO phenotype frequency: O (frequency: 38.5%) > B (29.4%) > A (24.1%) > AB (8.0%). The D-positive phenotype was far more common (99.5%) than the D-negative phenotype (0.5%). The phenotypic pattern globally is similar to previous reports in Southeast Asia. The D antigen distribution is similar to world distribution as the most common blood group. For the first time in Indonesia, this distribution of ABO and D phenotype is reported in a large-scale study. This work is a pioneer in the coordinated optimization of transfusion guidelines at the national level.

Hemolytic disease of the fetus and newborn-a perspective of immunohematology

BACKGROUND

Hemolytic disease of the fetus and newborn is a public health problem caused by maternal-fetal incompatibility; no prophylaxis is available for most alloantibodies that induce this disease. This study reviews the literature regarding which antibodies are the most common in maternal plasma and which were involved in hemolytic disease of the fetus and newborn.

METHOD

Seventy-five studies were included in this review using a systematic search. Two independent authors identified studies of interest from the PubMed and SciELO databases.

MAIN RESULTS

Forty-four case reports were identified, of which 11 babies evolved to death. From 17 prevalence studies, the alloimmunization rate was 0.17 % with 161 babies receiving intrauterine transfusions and 23 receiving transfusions after birth. From 28 studies with alloimmunized pregnant women (7616 women), 455 babies received intrauterine transfusions and 21 received transfusions after birth.

CONCLUSION

Rh, Kell, and MNS were the commonest blood systems involved. The geographical distribution of studies shows that as these figures vary between continents, more studies should be performed in different countries. Investing in early diagnosis is important to manage the risks and complications of hemolytic disease of the fetus and newborn.

Positive Direct Antiglobulin Test: Is It a Risk Factor for Significant Hyperbilirubinemia in Neonates with ABO Incompatibility?

OBJECTIVE

ABO blood group (ABO) incompatibility is a common cause of neonatal indirect hyperbilirubinemia. The direct antiglobulin test (DAT) can identify infants developing hemolytic disease. This study aims to evaluate the significance of DAT positivity among neonates with ABO incompatibility.

STUDY DESIGN

This retrospective study included 820 neonates with blood group A or B who were born to blood group O mothers. The study group consisted of neonates (n = 79) who had positive DAT, and the control group consisted of infants (n = 741) who had negative DAT. Demographic and clinical data of the neonates regarding jaundice were collected and compared statistically.

RESULTS

The bilirubin level at 24 hours of life (study group: 8 ± 2.6 mg/dL, control group: 6 ± 2.2 mg/dL, p < 0.001) and the highest bilirubin level (study group: 12.7 ± 3.6 mg/dL, control group: 10.4 ± 4.2 mg/dL, p < 0.001) were higher in infants with positive DAT. A total of 37 (46.8%) infants in the study group and 83 (11.2%) infants in the control group received phototherapy (PT) in the nursery (p < 0.001). In neonates with positive DAT, direct bilirubin level, duration of hospitalization, and PT in the nursery were higher (p = 0.002, <0.001, and <0.001, respectively), whereas hemoglobin level was lower (p < 0.001).

CONCLUSION

In neonates with ABO incompatibility, a positive DAT is a risk factor for developing significant hyperbilirubinemia. Close follow-up of newborn infants with ABO incompatibility is crucial for early detection and treatment of neonatal jaundice to avoid early and late complications.

KEY POINTS

· The clinical spectrum of ABO incompatibility varies widely.. · The ABO incompatibility with positive DAT are at greater risk for high bilirubin levels.. · Infants with blood group incompatibilities must be monitored closely..

A study on diagnostic performance of different immunohematological diagnostic tests in assessing the prevalence of ABO Hemolytic Disease of Newborn in the antenatal O group mothers and their neonatal outcome in a tertiary care hospital in Northern India

BACKGROUND

Hemolytic disease of the newborn (HDN) results in the decreased lifespan of the red cells. HDN related to ABO incompatibility is mostly unnoticed because routine screening is not being done. This study was done to assess the prevalence of ABO-HDN and to compare different immunohematological tests. Methods-In this study 213 O group mothers and the 122 ABO-incompatible newborns born to them were included. Quantifying the maternal IgG anti-A/anti-B antibody titer was done by Conventional Tube Technique (CTT) using Dithiothreitol (DTT) pretreated maternal serum. Hemolysin test was performed on the mothers having titer > 256. These cases were followed up and, after delivery, were monitored for ABO HDN, along with direct antiglobulin testing and elution studies. The prevalence of ABO-HDN was calculated, and the different diagnostic parameters of the tests were calculated. Results- The prevalence of ABO-HDN in our population was estimated to be 1.7%, 6.1% & 10.6% in our population, O group mothers, and O group mothers with ABOincompatible newborns, respectively. Maternal titer≥ 512 strongly correlated with ABOHDN. DAT positivity is a good predictor of ABO-HDN, especially using sensitive techniques. Maternal IgG titers have the highest sensitivity & Negative Predictive Value, while DAT has the highest specificity & Positive Predictive Value. Conclusion - Maternal ABO antibody titration may be advocated in the centers to identify high-risk groups. It can advocate institutional delivery and dedicated follow-up of newborns with ABO-HDN. Blood grouping & DAT may be performed in all newborns born to O blood group to identify high-risk cases.

Clinical value of combination detection of direct antiglobulin test and serum albumin globulin ratio in severe hyperbilirubinemia caused by ABO hemolytic disease of the newborn

Background To explore of a combination of antiglobulin test(DAT) and albumin globulin ratio(AGR) could predict the severity of ABO hemolytic disease of the newborn(ABO-HDN).Methods The measurement of DAT, AGR and combination detection of DAT and AGR was done to predict severe ABO-HDN hyperbilirubinemia in 270 full-term infants based on whether the infants received transfusions of blood components. The infants were divided into three groups according to the results of DAT and ARG and compared the differences of phototherapy day and hospitalization day of the three groups.Results Of the 270 cases enrolled in this study, 69 infants were DAT positive. Peak total bilirubin, AGR, and positive DAT were independently associated with the need for blood components transfusion. ROC curve analysis for blood components transfusion showed that DAT cutoff value >± with a sensitivity of 39.4% and a specificity of 83.9%, AGR cutoff value <2.05 with a sensitivity of 54.1% and a specificity of 85.7%, and combination detection of DAT and ARG with a sensitivity of 62.1% and a specificity of 91.2%. The AUCs for DAT, AGR, and combination detection of DAT and AGR were .621, .740, and .750 respectively. The phototherapy day and hospitalization day were significantly longer in group of AGR <2.05 and DAT >± than that of a group of AGR <2.05 and group of DAT >±.Conclusions DAT and ARG could be early predictors for the severity ABO-HDN hyperbilirubinemia and combination detection of DAT and AGR could further increase its predictive value.

Significance of immunohematologic testing in mother and newborn ABO incompatibility

The aim of this study was to define risk factors for jaundice and anemia in newborns with a positive direct antiglobulin test (DAT) and/or with an incompatible crossmatch due to ABO incompatibility between mother and newborn. ABO incompatibility has become a more significant cause of hemolytic disease of the fetus and newborn since the introduction of effective anti-D prophylaxis. The condition is common and, if clinically significant at all, causes only mild jaundice, which can be treated with phototherapy (PT). However, rare and serious presentations, requiring transfusion therapy, have been noted. Clinical, laboratory, and immunohematologic data were collected retrospectively from medical records of ABO-incompatible newborns and their mothers over a 5-year period (2016-2020) from University Hospital Centre Zagreb. Two groups of newborns were compared: those who needed medical intervention because of hyperbilirubinemia or anemia and those who did not. Within the group of newborns requiring intervention, we also compared those with A and B blood groups. Over the 5-year period, 72 of 184 (39%) newborns required treatment. The treatment was PT in 71 (38%) newborns and erythrocyte transfusion in 2 (1%). In 112 (61%) newborns, ABO incompatibility was an accidental finding while performing blood group typing; these newborns did not require any therapy. In conclusion, we found a statistical, but not clinically significant, difference between the groups of treated and untreated newborns, related to the mode of delivery and DAT positivity within hours of delivery. There were no statistically significant differences in characteristics between the groups of treated newborns, except for two newborns with blood group A who received erythrocyte transfusions.

A retrospective comparison of phototherapy need in O-B versus O-A incompatibility in a single Saudi institution

BACKGROUND

ABO incompatibility is a major risk factor for neonatal indirect hyperbilirubinemia (NIH), requiring treatment. It has been shown that there are racial differences in direct antiglobulin test (DAT) positivity and phototherapy need in the O--B versus (vs) O--A incompatibility. The comparison between the O--B and O--A incompatibility is not well studied in Saudi Arabia.

AIMS

We aimed to compare DAT positivity and phototherapy need in O-B vs O-A incompatibility in Saudi Arabia.

METHODS

This retrospective cohort study was conducted in one Saudi hospital. We included a convenience sample of neonates born between 01 January 2013 and 31 December 2021. We included healthy neonates admitted to the nursery care unit only, born at≥38 weeks gestation, and had normal G6PD levels. Neonates that had no G6PD level measurement or lost follow-up post-discharge were excluded. The data span was the first 14 days of life.

RESULTS

A total of 611 neonates met our inclusion criteria. Positive DAT was more prevalent in the O-B than the O-A incompatibility [43.5% vs 29.2%, p <  0.001). A greater odd of phototherapy need was observed in the O--B vs O-A incompatibility across various strata. Readmission for NIH, use of 360° exposure phototherapy, or intravenous immunoglobulin administration was more prevalent in the O-B than the O-A incompatibility (13.2% vs 5.0%, p <  0.001). A logistic regression analysis revealed that the O-B incompatibility modified the association between DAT positivity and phototherapy need.

CONCLUSIONS

The O-B incompatibility had a mediator effect on the relationship between DAT positivity and the need for phototherapy in the study population, which emphasizes that the O-B and O-A are not the same from the NIH point of view.

ABO hemolytic disease of the newborn: a need for clarity and consistency in diagnosis

The diagnosis of ABO hemolytic disease of the newborn (ABO HDN) has been the subject of considerable debate and clinical confusion. Its use as an overarching default diagnosis for hyperbilirubinemia in all ABO incompatible neonates regardless of serological findings is problematic and lacks diagnostic precision. Data on hemolysis indexed by carbon monoxide (CO) levels in expired air (ETCOc) and blood (COHbc) support an essential role for a positive direct antiglobulin test (DAT) in making a more precise diagnosis of ABO HDN. A working definition that includes ABO incompatibility, significant neonatal hyperbilirubinemia, and a positive DAT is needed to gain clarity and consistency in the diagnosis of ABO HDN. Absent a positive DAT, the diagnosis of ABO HDN is suspect. Instead, a negative DAT in a severely hyperbilirubinemic ABO incompatible neonate should trigger an exhaustive search for an alternative cause, a search that may require the use of targeted gene panels.

Early indicators of neonatal-onset hereditary thrombotic thrombocytopenia purpura

Background

Neonatal-onset hereditary thrombotic thrombocytopenia purpura (hTTP) is often misdiagnosed due to its rarity. It begins with jaundice, similar to infants with ABO incompatibility.

Objective

To explore early indicators of neonatal-onset hTTP.

Methods

This study was a retrospective case series of newborns with hTTP and ABO incompatibility. We compared the clinical characteristics and laboratory test results in these two groups.

Results

This study included four hTTP patients and 20 ABO-incompatible newborns. All patients manifested disease during the neonatal period. There were equal numbers of males and females in each group. hTTP newborns showed earlier (median difference, 57.0 h; 95% confidence interval [CI], 24.0-65.0) and more severe hyperbilirubinemia (mean difference, 8.0 mg/dl; 95% CI, 3.8-12.1) than ABO-incompatible newborns. In hTTP newborns, anemia was more common within 7 days after birth than in ABO-incompatible newborns (odds ratio, 25.4; 95% CI, 1.2-551.6), and platelet counts were lower than in ABO-incompatible newborns (17 ± 12 × 109/L vs. 291 ± 76 × 109/L). The levels of serum creatinine (median difference, 51.8 μmol/L; 95% CI, 16.0-109.4) and blood urea nitrogen (median difference, 5.7 mmol/L; 95% CI, 2.8-38.7) were higher in hTTP newborns than in ABO-incompatible newborns. There were no significant differences in white blood cell counts, C-reactive protein, alanine aminotransferase, or albumin levels.

Conclusions

Severe jaundice soon after birth, early anemia, and severe thrombocytopenia were more common in newborns with hTTP than ABO incompatibility. These are distinguishing early features of hTTP.

Hemolytic Disease of Newborn due to ABO Incompatibility between B Blood Group Mother and A Blood Group Neonate

ABO incompatibility between O blood group mother and non–O blood group neonate is common. It rarely causes anemia and hyperbilirubinemia in neonate, requiring invasive management. Direct antiglobulin test may be positive in these cases with immunoglobulin (Ig)-G antibody specificity. There are few cases of hemolytic disease of newborn due to ABO incompatibility between mother and newborn with non ̶ O blood group mother. After obtaining consent from the patient, we reported a case of incompatibility in a B blood group mother and A blood group neonate, and it was managed with phototherapy.

ABO haemolytic disease of the newborn: Improved prediction by novel integration of causative and protective factors in newborn and mother

BACKGROUND AND OBJECTIVES

Prediction of haemolytic disease of the foetus and newborn (HDFN) caused by maternal anti-A/-B enables timely therapy, thereby preventing the development of kernicterus spectrum disorder. However, previous efforts to establish accurate prediction methods have been only modestly successful.

MATERIALS AND METHODS

In a case-control study, we examined 76 samples from mothers and 76 samples from their newborns; 38 with and 38 without haemolysis. The IgG subclass profile of maternal anti-A and anti-B was determined by flow cytometry. Samples from newborns were genetically analysed for the A² subgroup, secretor and FcγRIIa receptor alleles.

RESULTS

Surprisingly, we found a correlation between the newborn secretor allele and haemolysis (p = 0.034). No correlation was found for FcγRIIa alleles. The A² subgroup was found only in newborns without haemolysis. Unexpectedly, different reaction patterns were found for maternal anti-A and anti-B; consequently, the results were treated separately. For the prediction of haemolysis in A-newborns, the maternal IgG1 subclass determination resulted in an accuracy of 83% at birth. For B-newborns, an accuracy of 91% was achieved by the maternal IgG2 subclass determination.

CONCLUSION

We improved the prediction of ABO-HDFN by characterizing maternal anti-A and anti-B by flow cytometry and we presented genetic traits in newborns with correlation to haemolysis. We propose a new understanding of A- and B-substances as immunogens that enhance the maternal immune response and protect the newborn, and we suggest that the development of ABO-HDFN is different when caused by maternal anti-A compared to maternal anti-B.

From A to AB: A Caucasian Mother with High Anti-B Titer Causing Hemolytic Disease of the Newborn

We report on a term infant with clinically significant hemolysis and hyperbilirubinemia. Testing revealed ABO incompatibility between maternal type A and infant type AB. The maternal alloantibody screen was negative. The infant's direct antiglobulin test was positive, and anti-B IgG was eluted off the infant's red blood cells (RBCs). Testing of the mother's plasma revealed a high anti-B titer. The infant was successfully treated with phototherapy and intravenous immunoglobulin. The bilirubin and hematocrit stabilized, and the infant was discharged home. This case was unusual because of its severity and unusual ABO constellation. Furthermore, this report is an exemplary educational case study on how effective collaboration between the clinical team and the blood bank laboratory is critical in reaching the correct diagnosis. In summary, the differential diagnosis of more unusual and atypical ABO-incompatible constellations must be considered when an infant presents with unexplained hemolysis.

Hemolytic Disease of the Fetus and Newborn Caused by Anti-Group A IgG From a Group B Mother

ABO incompatibility has emerged as the premier reason for hemolytic disease of the fetus and newborn (HDFN). It always occurs in the offspring of blood group O mother. We present a rare case that the fetus of group A got HDFN caused by the anti-group A immunoglobulin G from a group B mother. The direct Coombs test of the fetus blood was negative, but the indirect Coombs test on A1 standard blood cells was strong positive (4+). The acid release test of antibody on the membrane of red blood cells to A1 standard blood cells was also strong positive (4+). Bilirubin of the fetus reached the threshold of exchange transfusion, but she just received 4 days' phototherapy and 2.2 g albumin intravenous injection, with no packed blood cells transfusion, because her family refused, and came to a favorable outcome. This case reminds us not to ignore the possibility of HDFN in offspring of mothers with non-O blood group.

Direct antiglobulin test in the prediction of hyperbilirubinemia and predischarge bilirubin levels in infants with mother-infant blood type incompatibility

BACKGROUND

This research evaluated the association between the mother-infant blood type or rhesus (ABO or Rh) incompatibility, the pattern of neonatal jaundice, and serum bilirubin (TSB) values obtained prior to discharge from hospital of healthy born neonates with gestational age >34 weeks and birth weight >2000 g.

METHODS

We utilized a laboratory and neonatal database to identify the cord blood ABO/Rh and direct antiglobulin test (DAT) and TSB measured during hospitalization and re-admission with hyperbilirubinemia for phototherapy treatment. We used hour-specific TSB to analyze the TSB levels for ABO/Rh compatibility and isoimmunization using chi-square, analysis of variance, and regression models.

RESULTS

Of the 901 infants studied, 158 (17.5%) had ABO/Rh incompatibility, including 27 with positive DAT. Hyperbilirubinemia was diagnosed in 33.3% DAT positive, 6.9% DAT negative, and 4.6% of infants with compatible blood types. Increased predischarge TSB was observed in DAT positive infants at 48-72 h of postnatal age (P < 0.001). After controlling for age at TSB testing and weight loss percentage, multiple regression analysis did not show any impact of ABO/Rh incompatibility and DAT results on the predischarge TSB levels.

CONCLUSION

Blood type incompatibility increases the frequency of hyperbilirubinemia only in the DAT-positive infants. Irrespective of the isoimmunization status, it does not significantly affect the level of predischarge TSB.

Intravenous immunoglobulin G in the treatment of ABO hemolytic disease of the newborn during the early neonatal period at a tertiary academic hospital: a retrospective study

OBJECTIVE

To evaluate the efficacy and safety of intravenous immunoglobulin G (IVIG) in infants with ABO hemolytic disease of the newborn (HDN).

METHODS

Infants with moderate-to-severe ABO HDN during early neonatal period (<7 days) at our hospital in 2017 were included in this retrospective study. Patients treated with IVIG and phototherapy were classified as the IVIG group, and those who only received phototherapy were classified as the phototherapy only group.

RESULTS

Forty-six patients were classified into the IVIG group and 68 other patients were classified into the phototherapy only group. There was no significant difference in duration of phototherapy, hospitalization periods, needs for exchange transfusion, transfusions, and incidence of bilirubin-induced neurological sequelae between these two groups (P = 0.20, 0.27, 0.65, 0.47, 0.78, respectively).

CONCLUSION

It seems unnecessary to expose neonates to IVIG in moderate-to-severe ABO HDN when the available data show no appreciable benefits.

Next Generation Sequencing-Based Fetal ABO Blood Group Prediction by Analysis of Cell-Free DNA from Maternal Plasma

Introduction

ABO blood group incompatibility between a pregnant woman and her fetus as a cause of morbidity or mortality of the fetus or newborn remains an important, albeit rare, risk. When a pregnant woman has a high level of anti-A or anti-B IgG antibodies, the child may be at risk for hemolytic disease of the fetus and newborn (HDFN). Performing a direct prenatal determination of the fetal ABO blood group can provide valuable clinical information.

Objective

Here, we report a next generation sequencing (NGS)-based assay for predicting the prenatal ABO blood group.

Materials and Methods

A total of 26 plasma samples from 26 pregnant women were tested from gestational weeks 12 to 35. Of these samples, 20 were clinical samples and 6 were test samples. Extracted cell-free DNA was PCR-amplified using 2 primer sets followed by NGS. NGS data were analyzed by 2 different methods, FASTQ analysis and a grep search, to ensure robust results. The fetal ABO prediction was compared with the known serological infant ABO type, which was available for 19 samples.

Results

There was concordance for 19 of 19 predictable samples where the phenotype information was available and when the analysis was done by the 2 methods. For immunized pregnant women (n = 20), the risk of HDFN was predicted for 12 fetuses, and no risk was predicted for 7 fetuses; one result of the clinical samples was indeterminable. Cloning and sequencing revealed a novel variant harboring the same single nucleotide variations as ABO*O.01.24 with an additional c.220C>T substitution. An additional indeterminable result was found among the 6 test samples and was caused by maternal heterozygosity. The 2 indeterminable samples demonstrated limitations to the assay due to hybrid ABO genes or maternal heterozygosity.

Conclusions

We pioneered an NGS-based fetal ABO prediction assay based on a cell-free DNA analysis from maternal plasma and demonstrated its application in a small number of samples. Based on the calculations of variant frequencies and ABO*O.01/ABO*O.02 heterozygote frequency, we estimate that we can assign a reliable fetal ABO type in approximately 95% of the forthcoming clinical samples of type O pregnant women. Despite the vast genetic variations underlying the ABO blood groups, many variants are rare, and prenatal ABO prediction is possible and adds valuable early information for the prevention of ABO HDFN.

Silica microbeads capture fetal nucleated red blood cells for noninvasive prenatal testing of fetal ABO genotype

ABO hemolytic disease of the newborn (ABO-HDN), which may cause neonatal jaundice and polycythemia, or even stillbirth or neonatal death, is widespread in China. Prenatal testing for the fetal ABO blood group can reduce unnecessary concerns or ensure prompt treatment. Herein, we presented a method to employ high-density silica microbeads (SiO₂ MBs) for capturing fetal nucleated red blood cells (fnRBCs) in maternal peripheral blood, and we detected the ABO genotype of the fetus using these captured cells. We evaluated 52 patients using the SiO₂ MBs. Among 26 pregnant women with type O blood, 8 (30.8%) of the fetuses had type A blood, 5 (19.2%) had type B blood, and 13 (50%) had type O blood. SRY genes were detected in all 27 male fetuses. This study represents a simple and effective method for noninvasive prenatal detection of the fetal ABO genotype. We believe that this method has great potential for noninvasive prenatal testing of the fetal Rh blood group and other fetal diseases as well.

Severe Fetal Hemolysis and Cholestasis Due to High-Titer Maternal IgG Anti-A Antibodies

ABO blood group incompatibility between mother and fetus can lead to hemolytic disease of the fetus and newborn (HDFN). We present the first case of severe O/A HDFN associated with extremely high-titer (1:32 000) immunoglobulin G anti-A antibodies in a Cameroon mother. Cord blood analysis revealed severe fetal hemolytic anemia and conjugated hyperbilirubinemia. After exclusion of an underlying disease and other risk factors, cholestasis resolved after treatment with ursodeoxycholic acid, a red blood cell transfusion, and intravenous immunoglobulins. This case is presented to create awareness for a more severe course of ABO HDFN in nonwhite and non-European mother-child pairs.