Cell-free DNA screening for common autosomal trisomies using rolling-circle replication in twin pregnancies.

OBJECTIVE: To evaluate the performance of prenatal screening for common autosomal trisomies in twin pregnancies through the use of rolling-circle replication (RCR)-cfDNA as a first-tier test. METHOD: Prospective multicenter study. Women who underwent prenatal screening for trisomy (T) 21, 18 and 13 between January 2019 and March 2022 in twin pregnancies were included. Patients were included in two centers. The primary endpoint was the rate of no-call results in women who received prenatal screening for common autosomal trisomies by RCR-cfDNA at the first attempt, compared to that in prospectively collected samples from 16,382 singleton pregnancies. The secondary endpoints were the performance indices of the RCR-cfDNA. RESULTS: 862 twin pregnancies underwent screening for T21, T18 and T13 by RCR-cfDNA testing at 10-33 weeks' gestation. The RCR-cfDNA tests provided a no-call result from the first sample obtained from the patients in 107 (0.7%) singleton and 17 (2.0%) twin pregnancies. Multivariable regression analysis demonstrated that significant independent predictors of test failure were twin pregnancy and in vitro fertilization conception. All cases of T21 (n = 20/862; 2.3%), T18 (n = 4/862; 0.5%) and T13 (n = 1/862; 0.1%) were correctly detected by RCR-cfDNA (respectively, 20, 4 and 1 cases). Sensitivity was 100% (95% CI, 83.1%-100%), 100% (95% CI 39.8%-100%) and 100% (95% CI 2.5%-100%) for T21, T18 and T13, respectively, in twin pregnancies. CONCLUSION: The RCR-cfDNA test appears to have good accuracy with a low rate of no-call results in a cohort of twin pregnancies for the detection of the most frequent autosomal trisomies.

Lack of the human choline transporter-like protein SLC44A2 causes hearing impairment and a rare red blood phenotype.

Blood phenotypes are defined by the presence or absence of specific blood group antigens at the red blood cell (RBC) surface, due to genetic polymorphisms among individuals. The recent development of genomic and proteomic approaches enabled the characterization of several enigmatic antigens. The choline transporter-like protein CTL2 encoded by the SLC44A2 gene plays an important role in platelet aggregation and neutrophil activation. By investigating alloantibodies to a high-prevalence antigen of unknown specificity, found in patients with a rare blood type, we showed that SLC44A2 is also expressed in RBCs and carries a new blood group system. Furthermore, we identified three siblings homozygous for a large deletion in SLC44A2, resulting in complete SLC44A2 deficiency. Interestingly, the first-ever reported SLC44A2-deficient individuals suffer from progressive hearing impairment, recurrent arterial aneurysms, and epilepsy. Furthermore, SLC44A2null individuals showed no significant platelet aggregation changes and do not suffer from any apparent hematological disorders. Overall, our findings confirm the function of SLC44A2 in hearing preservation and provide new insights into the possible role of this protein in maintaining cerebrovascular homeostasis.

Pilot study on the use of basophil activation tests and skin tests for the prevention of allergic transfusion reactions.

Background and objectives: Management of severe allergic transfusion reactions (ATR) is challenging. In this study, we investigate the usefulness of skin tests and basophil activation tests (BAT) in chronically transfused patients for the prevention of future ATR. Materials and methods: BAT and skin tests were carried with the supernatant of red blood cell (RBC) units for a sickle-cell disease patient under chronic exchange transfusion who has presented a severe ATR, in order to prevent potential future ATR. If the results for both BAT and skin tests were negative, the RBC units could be transfused to the patient. If either one of the results was positive, the tested RBC unit was discarded for the patient. Results: 192 RBC units were tested with both tests. The level of results concordance between the two tests was 95%. Out of the 169 negative units with both tests, 118 units were transfused to the patient for which he presented no ATR. Conclusion: In our study, combining both BAT and skin tests was associated with a good negative predictive value since we were able to safely transfuse our patient. Further studies are still necessary to confirm this result but this pilot study indicates that skin tests and BAT might help prevent ATR. When BAT is not available, skin tests may also be useful in preventing ATR.

Management of sickle cell disease during pregnancy: experience in a third-level hospital and future recommendations.

OBJECTIVE: To describe the outcomes of sickle-cell disease in pregnancy according to the different treatments adopted before and during pregnancy and to propose a systematic approach to treat sickle-cell disease (SCD) during pregnancy. METHODS: A retrospective descriptive study compared pregnancy outcomes among women with SCD who stopped hydroxyurea (HU) once pregnant (Group 1), were never treated before and during pregnancy (Group 2) or were treated by HU before conception who received prophylactic transfusion during pregnancy (Group 3). For each group we recorded the population's characteristics and the transfusion-related, obstetrical, perinatal and SCD complications. RESULTS: We found 11 patients for group 1 (9/11 with at least 3 painful crises during the 12 months before conception), 4 for group 2 (3/4 with no sickle-cell complications during the year before pregnancy) and 2 for group 3 (one with previous multiorgan failure (MOF), one with previous stroke). No transfusion-related complication occurred. Group 1 and 2 developed SCD complications and a high number of acute transfusions and hospital admissions. Group 3 showed none of these complications, but one patient developed preeclampsia and preterm birth. Several obstetrical and perinatal complications occurred in group 1. CONCLUSION: Not treating sickle-cell during pregnancy increases maternal and perinatal morbidity, even in mildly affected women. All sickle-cell pregnancies should be treated, according to the treatment adopted before but also to patient's SCD-history. We propose chronic transfusion to women with previous stroke or MOF or already under transfusion program, and HU for severely and mildly affected patients, respectively from the second and third trimesters. Additional prospective studies are needed to validate the results of the proposed protocol.

Low Levels of Natural Anti-α-N-Acetylgalactosamine (Tn) Antibodies Are Associated With COVID-19.

Human serum contains large amounts of anti-carbohydrate antibodies, some of which may recognize epitopes on viral glycans. Here, we tested the hypothesis that such antibodies may confer protection against COVID-19 so that patients would be preferentially found among people with low amounts of specific anti-carbohydrate antibodies since individual repertoires vary considerably. After selecting glycan epitopes commonly represented in the human anti-carbohydrate antibody repertoire that may also be expressed on viral glycans, plasma levels of the corresponding antibodies were determined by ELISA in 88 SARS-CoV-2 infected individuals, including 13 asymptomatic, and in 82 non-infected controls. We observed that anti-Tn antibodies levels were significantly lower in patients as compared to non-infected individuals. This was not observed for any of the other tested carbohydrate epitopes, including anti-αGal antibodies used as a negative control since the epitope cannot be synthesized by humans. Owing to structural homologies with blood groups A and B antigens, we also observed that anti-Tn and anti-αGal antibodies levels were lower in blood group A and B, respectively. Analyses of correlations between anti-Tn and the other anti-carbohydrates tested revealed divergent patterns of correlations between patients and controls, suggesting qualitative differences in addition to the quantitative difference. Furthermore, anti-Tn levels correlated with anti-S protein levels in the patients' group, suggesting that anti-Tn might contribute to the development of the specific antiviral response. Overall, this first analysis allows to hypothesize that natural anti-Tn antibodies might be protective against COVID-19.

Covid-19 and blood groups: ABO antibody levels may also matter.

BACKGROUND: Susceptibility to Covid-19 has been found to be associated with the ABO blood group, with O type individuals being at a lower risk. However, the underlying mechanism has not been elucidated. Here, we aimed to test the hypothesis that Covid-19 patients might have lower levels of ABO antibodies than non-infected individuals as they could offer some degree of protection. METHODS: After showing that the viral spike protein harbors the ABO glycan epitopes when produced by cells expressing the relevant glycosyltransferases, like upper respiratory tract epithelial cells, we enrolled 290 patients with Covid-19 and 276 asymptomatic controls to compare their levels of natural ABO blood group antibodies. RESULTS: We found significantly lower IgM anti-A + anti-B agglutination scores in blood group O patients (76.93 vs 88.29, P-value = 0.034) and lower levels of anti-B (24.93 vs 30.40, P-value = 0.028) and anti-A antibodies (28.56 vs 36.50, P-value = 0.048) in blood group A and blood group B patients, respectively, compared to controls. CONCLUSION: In this study, we showed that ABO antibody levels are significantly lower in Covid-19 patients compared to controls. These findings could indicate that patients with low levels of ABO antibodies are at higher risk of being infected.

A Tutsi family harbouring two new RHCE variant alleles and a new haplotype in the Rh blood group system.

BACKGROUND: RHCE*ceEK is a rare RH allele mostly encountered in people of African descent. This allele is defined by four single nucleotide substitutions: c.48G>C, c.712A>G, c.787A>G and c.800T>A. Until now, it has only been reported to segregate with either RHD*01N.01 or RHD*DAR1.00. MATERIALS AND METHODS: Blood samples were drawn from a 32-year-old Tutsi pregnant woman during an antenatal visit in order to perform her type and screen. To further investigate the results found in the patient, a family study was conducted. Standard haemagglutination methods were used to investigate the subjects' red blood cells and plasma. Molecular workup on RHD and RHCE genes was carried out by DNA microarray, real-time PCR and DNA sequencing techniques. RESULTS: The patient was phenotyped as group B, D+C-E-c+e+, Hr-. A complex mixture of anti-E, anti-c, anti-Hr and anti-hrS was detected in her plasma. She was found to carry a normal RHD gene, a conventional RHCE*ceEK allele and an alternative RHCE*ceEK allele (RHCE*ceEK without c.48G>C). The family study showed that the conventional RHCE*ceEK and the alternative RHCE*ceEK alleles were associated with a RHD*01 allele and a RHD*01N.01 allele, respectively. Molecular analysis performed in the proband's mother showed a novel RHCE*ce variant allele on a RHCE*ceS -like background (RHCE*ceS with c.609G>A). CONCLUSIONS: This case study brought out new associations between RHD and RHCE alleles encoding the rare Hr- phenotype: the conventional RHCE*ceEK allele linked to the RHD*01 allele and an alternative RHCE*ceEK allele associated with the RHD*01N.01 allele. A novel RHCE*ce variant (RHCE*ceS with c.609G>A) was also reported.

Acute hemolytic transfusion reaction associated with anti-Mta : case report and review of the literature.

BACKGROUND: Mta (MNS14) is a low-prevalence antigen of the MNS system. A few cases of hemolytic disease of the fetus and newborn caused by anti-Mta have been reported in the literature, but up to now this antibody has never been associated with a hemolytic transfusion reaction (HTR). CASE REPORT: A 38-year-old male with sickle cell disease undergoing exchange transfusion presented with shivering, nausea, dyspnea, and pain in the lower limbs. Biologic parameters showed increased hemolysis. The administered red blood cell (RBC) units had been issued by electronic crossmatch due to a negative antibody screening test. In the posttransfusion investigations, crossmatch of the transfused RBC units with the patient's serum showed incompatibility of one unit. The presence of an antibody against a low-prevalence antigen was suspected and further serologic testing was performed for identification. RESULTS: Anti-Mta was identified in the patient's serum. The RBCs of the incompatible unit implicated in the HTR were Mt(a+). An eluate of a posttransfusion blood sample of the patient was nonreactive with the incompatible RBCs, and the direct antiglobulin test was negative. CONCLUSION: To our knowledge, this is the first case report of an HTR associated with anti-Mta .

Automated RBC exchange compared to manual exchange transfusion for children with sickle cell disease is cost-effective and reduces iron overload.

BACKGROUND: Chronic transfusion in sickle cell disease (SCD) remains the gold standard therapy for stroke prevention and for patients with severe disease despite adequate hydroxyurea treatment. The aim of our study was to assess the safety and efficacy of automated red blood cell exchange (aRBX) in patients with SCD previously treated with manual exchange transfusion (MET). Costs related to transfusion and chelation overtime were evaluated. STUDY DESIGN AND METHODS: Beginning in January 2012, children with SCD who weighed 30 kg or more on MET could switch to aRBX. Clinical, biological, and procedures' data, including costs, were recorded for the last 6 months on MET and compared to those after the first and the second year on aRBX. RESULTS: Ten patients switched from MET to aRBX at a median age of 11.8 years. After the switch, median hemoglobin S (HbS) increased significantly (33.5% on MET compared to 45% on aRBX; p < 0.001) but remained in the target values for all patients. Median ferritin decreased significantly (663.3 µg/L on MET compared to 126.8 µg/L on aRBX; p < 0.001) and intervals between procedures were significantly longer. The requirements of red blood cells (RBCs)/kg/year were not different on MET (0.88 unit/kg/year) than during the second year on aRBX (1.07 unit/kg/year; p = NS). MET costs were similar compared to aRBX since chelation was stopped in previously treated patients. CONCLUSION: Erythrocytapheresis reduces iron overload and allows a longer interval between procedures without a higher RBC requirement from the second year on aRBX. The cost did not increase as estimated in our Belgian Health Care System.

Transfusion-related acute lung injury.

Transfusion-related acute lung injury (TRALI) is defined as the onset or the worsening of respiratory distress within 6  h of the transfusion of a plasma-containing blood component. It is currently considered to be one of the leading causes of severe posttransfusion morbidity and acute mortality in countries with a high development index. Understanding of the pathogenesis of TRALI has resulted in the development of preventive measures that have contributed to reducing its incidence. Early recognition of the clinical symptoms allow the clinician to identify the syndrome and to undertake therapeutic measures that may reduce the morbidity and mortality associated with this complication.

Blood storage duration and morbidity and mortality in children undergoing cardiac surgery. A retrospective analysis.

BACKGROUND: Blood transfusion is frequently required in children undergoing cardiac surgery and is associated with altered postoperative outcome. This may be due to alterations in red blood cell properties related to the storage process. OBJECTIVE: To evaluate the effect of blood storage duration on postoperative morbidity and mortality in children undergoing cardiac surgery. DESIGN: A retrospective review of a paediatric cardiac surgery database. SETTING: Department of Anaesthesiology, Queen Fabiola Children's University Hospital, Brussels, Belgium. PARTICIPANTS: Children transfused with one or two units of blood in the perioperative period. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Storage duration was used to allocate children to the Group 'Young' or the Group 'Old' (cut-off = 7 days). The primary endpoint was a composite based on the incidence of hospital mortality and/or the incidence of at least one organ failure. RESULTS: From 1014 children in the database, 570 were included in the final analysis. One hundred and eighteen patients were included in the Group 'Young' [median (interquartile range, IQR) storage duration 6 (5 to 7) days] and 452 in the Group 'Old' [storage duration 14 (11 to 19) days]. No difference was found in mortality, length of ICU stay, mechanical ventilation duration, postoperative infection and major organ dysfunction. Duration of storage used as a continuous variable did not influence the incidence of the composite endpoint when evaluated by univariate or multivariate logistic regression analyses. CONCLUSION: Red blood cell storage duration did not influence postoperative morbidity and mortality in paediatric cardiac surgery patients transfused with one or two units of blood.

Transfusion support of autoimmune hemolytic anemia: how could the blood group genotyping help?

Conventional pretransfusion testing based on hemagglutination assays can be challenging for patients with autoimmune hemolytic anemia (AIHA) because of the presence of auto-antibodies. It has been suggested that deoxyribonucleic acid-based methods could be more efficient in the selection of antigen-matched red blood cell units in those settings. Because of the high risk of alloimmunization of these patients and the labor-intensive nature of adsorption techniques, we decided to evaluate the feasibility of selecting antigen-matched units on the basis of RBC genotyping. We included in our routine RBC genotyping program samples from 7 patients with AIHA presenting a strongly positive direct antiglobulin test. This made the routine compatibility tests difficult. Most patients had previously received transfusions because of warm AIHA. Matched donor units were selected according to the genotype. For all but 1 patient, blood group genotyping could be done on time to allow antigen-matched transfusion. Four patients received antigen-matched red blood cell units based on RBC genotyping and for 1 patient the fact that no matched units were available led us to postpone the transfusion. After each transfusion, the recovery was recorded and considered satisfactory for all transfused patients.

Evaluation of immunochemiluminometric assays for the measurement of insulin and C-peptide using the ADVIA Centaur.

We evaluated new immunochemiluminometric assays (ICMAs) for insulin and C-peptide (ADVIA Centaur Insulin & C-Peptide-Serum assays). Both ADVIA Centaur assays are two-site sandwich immunoassays using direct chemiluminescent technology. Precision was investigated using serum pools at three levels of the two analytes, measured in duplicate for 10 days. Total Coefficient of Variations (CVs) were 5, 7 and 4% for insulin and 9, 6 and 10% for C-peptide, with intra-assay precisions of 5, 4 and 5% and 5, 3 and 3%, respectively. The minimum detectable concentrations were 0.5 mU/L and < 0.1 microg/L for insulin and for C-peptide, respectively. Day-to-day reproducibility of single measurements was 5.4, 7.1 and 4.3% for pools with an insulin concentration of 0.6 mU/L, 2.0 mU/L and 4.0 mU/L; it was 4.4, 6.6 and 5.3% for pools with a C-peptide concentration of 0.2, 0.3 and 1.0 microg/L. The functional sensitivity did not differ from 3 SD Minimal Detectable Concentration (MDC) (0.5 mU/L for insulin and < 0.1 microg/L for C-peptide). The linearity was good in the range of 0.6-20 mU/L for insulin and 0.3-9 microg/L for C-peptide. The comparison with the RIA used in our laboratory was analyzed by Passing-Bablok and Bland-Altman plots and revealed a proportional bias of approximately 20% (slope: 1.20; CI: 1.14 to 1.26) for C-peptide and a systematic bias of -1.6 mU/L (slope: 0.94; CI: 2.7 to -0.5) for insulin which should not have any clinical consequence in the interpretation of results. Finally, we tested the influence of hemolysis on insulin in serum and plasma and found the same negative effect for both samples when more than 2% of red cells were hemolyzed, and this effect increased with the lag time before freezing. In conclusion, both assays were satisfactorily correlated with the routine RIA test used in our laboratory. The major problem was the sensitivity to hemolysis which is common to all insulin immunometric assays.