RNA Sequencing Reveals Candidate Genes and Pathways Associated with Resistance to MDM2 Antagonist Idasanutlin in TP53 Wild-Type Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) is a genetically and clinically diverse hematological cancer affecting middle-aged and elderly individuals. Novel targeted therapy options are needed for patients who relapse following initial responses or who are intrinsically resistant to current treatments. There is a growing body of investigation currently underway on MDM2 inhibitors in clinical trials, reflecting the increasing interest in including these drugs in cancer treatment regimens. One of the developed compounds, idasanutlin (RG7388), has shown promise in early-stage clinical trials. It is a second-generation MDM2-p53-binding antagonist with enhanced potency, selectivity, and bioavailability. In addition to the TP53 status, which is an important determinant of the response, we have shown in our previous studies that the SF3B1 mutational status is also an independent predictive biomarker of the ex vivo CLL patient sample treatment response to RG7388. The objective of this study was to identify novel biomarkers associated with resistance to RG7388. Gene set enrichment analysis of differentially expressed genes (DEGs) between RG7388-sensitive and -resistant CLL samples showed that the increased p53 activity led to upregulation of pro-apoptosis pathway genes while DNA damage response pathway genes were additionally upregulated in resistant samples. Furthermore, differential expression of certain genes was detected, which could serve as the backbone for novel combination treatment approaches. This research provides preclinical data to guide the exploration of drug combination strategies with MDM2 inhibitors, leading to future clinical trials and associated biomarkers that may improve outcomes for CLL patients.

Expression and Activity of the NF-κB Subunits in Chronic Lymphocytic Leukaemia: A Role for RelB and Non-Canonical Signalling.

BACKGROUND: Canonical NF-κB signalling by p65 (RelA) confers chemo-resistance and poor survival in chronic lymphocytic leukaemia (CLL). The role of non-canonical NF-κB signalling (leading to RelB and p52 subunit activation) in CLL is less understood, but given its importance in other B-cell tumour types, we theorised that RelB and p52 may also contribute to the pathology of CLL. METHODS: DNA binding activity of all five NF-kB subunits, p65, p50, RelB, p52, and c-Rel, was quantified using ELISA and correlated to ex vivo chemoresistance, CD40L-stimulated signalling (to mimic the lymph node microenvironment), and clinical data. RESULTS: Importantly, we show for the first time that high basal levels of RelB DNA binding correlate with nuclear RelB protein expression and are associated with del(11q), ATM dysfunction, unmutated IGHV genes, and shorter survival. High levels of nuclear p65 are prevalent in del(17p) cases (including treatment-naïve patients) and also correlate with the outcome. CD40L-stimulation resulted in rapid RelB activation, phosphorylation and processing of p100, and subsequent CLL cell proliferation. CONCLUSIONS: These data highlight a role for RelB in driving CLL cell tumour growth in a subset of patients and therefore strategies designed to inhibit non-canonical NF-κB signalling represent a novel approach that will have therapeutic benefit in CLL.

SF3B1 Mutations Are Associated with Resistance to Non-Genotoxic MDM2 Inhibition in Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) is a genetically and clinically heterogeneous malignancy affecting older individuals. There are a number of current treatment options for CLL, including monoclonal antibodies, targeted drugs, chemotherapy, and different combinations of these. However, for those patients who are intrinsically treatment resistant, or relapse following initial responses, novel targeted therapies are still needed. Targeting the mouse double-minute-2 human homolog (MDM2), a primary negative regulator of p53, is an appealing therapeutic strategy for non-genotoxic reactivation of p53, since the TP53 gene is in its wild-type state at diagnosis in approximately 90% of patients. Mutated SF3B1 and TP53 are both associated with more aggressive disease, resistance to therapies and poorer overall survival for CLL. In this study, we performed a screen for SF3B1 and TP53 mutations and tested RG7388 (idasanutlin), a second-generation MDM2 inhibitor, in a cohort of CLL primary patient samples. SF3B1 mutations were detected in 24 of 195 cases (12.3%) and found associated with poor overall survival (hazard ratio [HR] 2.12, p = 0.032) and high CD38 expression (median CD38 (%) 32 vs. 5; p = 0.0087). The novel striking finding of this study was an independent link between SF3B1 mutational status and poor response to RG7388. Overall, SF3B1 mutations in CLL patient samples were associated with resistance to treatment with RG7388 ex vivo, and patients with the wild type for both SF3B1 and TP53 are more likely to benefit from treatment with MDM2 inhibitors.

Splicing Modulation Results in Aberrant Isoforms and Protein Products of p53 Pathway Genes and the Sensitization of B Cells to Non-Genotoxic MDM2 Inhibition.

Several molecular subtypes of cancer are highly dependent on splicing for cell survival. There is a general interest in the therapeutic targeting of splicing by small molecules. E7107, a first-in-class spliceosome inhibitor, showed strong growth inhibitory activities against a large variety of human cancer xenografts. Chronic lymphocytic leukaemia (CLL) is a clinically heterogeneous hematologic malignancy, with approximately 90% of cases being TP53 wild-type at diagnosis. An increasing number of studies are evaluating alternative targeted agents in CLL, including MDM2-p53 binding antagonists. In this study, we report the effect of splicing modulation on key proteins in the p53 signalling pathway, an important cell death pathway in B cells. Splicing modulation by E7107 treatment reduced full-length MDM2 production due to exon skipping, generating a consequent reciprocal p53 increase in TP53WT cells. It was especially noteworthy that a novel p21WAF1 isoform with compromised cyclin-dependent kinase inhibitory activity was produced due to intron retention. E7107 synergized with the MDM2 inhibitor RG7388, via dual MDM2 inhibition; by E7107 at the transcript level and by RG7388 at the protein level, producing greater p53 stabilisation and apoptosis. This study provides evidence for a synergistic MDM2 and spliceosome inhibitor combination as a novel approach to treat CLL and potentially other haematological malignancies.

Genome-wide association study identifies risk loci for progressive chronic lymphocytic leukemia.

Prognostication in patients with chronic lymphocytic leukemia (CLL) is challenging due to heterogeneity in clinical course. We hypothesize that constitutional genetic variation affects disease progression and could aid prognostication. Pooling data from seven studies incorporating 842 cases identifies two genomic locations associated with time from diagnosis to treatment, including 10q26.13 (rs736456, hazard ratio (HR) = 1.78, 95% confidence interval (CI) = 1.47-2.15; P = 2.71 × 10-9) and 6p (rs3778076, HR = 1.99, 95% CI = 1.55-2.55; P = 5.08 × 10-8), which are particularly powerful prognostic markers in patients with early stage CLL otherwise characterized by low-risk features. Expression quantitative trait loci analysis identifies putative functional genes implicated in modulating B-cell receptor or innate immune responses, key pathways in CLL pathogenesis. In this work we identify rs736456 and rs3778076 as prognostic in CLL, demonstrating that disease progression is determined by constitutional genetic variation as well as known somatic drivers.

Epigenome-wide analysis reveals functional modulators of drug sensitivity and post-treatment survival in chronic lymphocytic leukaemia.

BACKGROUND: Chronic lymphocytic leukaemia (CLL) patients display a highly variable clinical course, with progressive acquisition of drug resistance. We sought to identify aberrant epigenetic traits that are enriched following exposure to treatment that could impact patient response to therapy. METHODS: Epigenome-wide analysis of DNA methylation was performed for 20 patients at two timepoints during treatment. The prognostic significance of differentially methylated regions (DMRs) was assessed in independent cohorts of 139 and 163 patients. Their functional role in drug sensitivity was assessed in vitro. RESULTS: We identified 490 DMRs following exposure to therapy, of which 31 were CLL-specific and independent of changes occurring in normal B-cell development. Seventeen DMR-associated genes were identified as differentially expressed following treatment in an independent cohort. Methylation of the HOXA4, MAFB and SLCO3A1 DMRs was associated with post-treatment patient survival, with HOXA4 displaying the strongest association. Re-expression of HOXA4 in cell lines and primary CLL cells significantly increased apoptosis in response to treatment with fludarabine, ibrutinib and idelalisib. CONCLUSION: Our study demonstrates enrichment for multiple CLL-specific epigenetic traits in response to chemotherapy that predict patient outcomes, and particularly implicate epigenetic silencing of HOXA4 in reducing the sensitivity of CLL cells to therapy.

Non-genotoxic MDM2 inhibition selectively induces a pro-apoptotic p53 gene signature in chronic lymphocytic leukemia cells.

Chronic lymphocytic leukemia (CLL) is a clinically heterogeneous hematologic malignancy. In approximately 90% of cases the TP53 gene is in its wildtype state at diagnosis of this malignancy. As mouse double-minute-2 homolog (MDM2) is a primary repressor of p53, targeting this protein is an attractive therapeutic approach for non-genotoxic reactivation of p53. Since the discovery of the first MDM2 inhibitor, Nutlin-3a, newer potent and bioavailable compounds have been developed. In this study we tested the second-generation MDM2 inhibitor, RG7388, in patient-derived CLL cells and normal cells, examining its effect on the induction of p53-transcriptional targets. RG7388 potently decreased viability in p53-functional CLL cells, whereas p53-non-functional samples were more resistant to the drug. RG7388 induced a pro-apoptotic gene expression signature with upregulation of p53-target genes involved in the intrinsic (PUMA, BAX) and extrinsic (TNFRSF10B, FAS) pathways of apoptosis, as well as MDM2 Only a slight induction of CDKN1A was observed and upregulation of pro-apoptotic genes dominated, indicating that CLL cells are primed for p53-dependent apoptosis. Consequently, RG7388 led to a concentration-dependent increase in caspase-3/7 activity and cleaved poly (ADP-ribose) polymerase. Importantly, we observed a preferential pro-apoptotic signature in CLL cells but not in normal blood and bone marrow cells, including CD34+ hematopoietic cells. These data support the further evaluation of MDM2 inhibitors as a novel additional treatment option for patients with p53-functional CLL.

Efficiency and Health Economic Evaluations of BD OneFlow™ Flow Cytometry Reagents for Diagnosing Chronic Lymphoid Leukemia.

REASON FOR THE STUDY: To standardize the use of flow cytometry for classifying hematological malignancies and make the results reliable and reproducible across laboratories, the EuroFlow™ Consortium published a comprehensive specification of antibody-fluorochrome conjugates, standard protocols, and algorithms for analysis. The BD OneFlow™ system builds on, and further standardizes, the EuroFlow protocols. We aimed to assess the effects on safety, efficiency, and costs for laboratories of adopting the BD OneFlow reagent tubes (LST and B-CLPD T1) for diagnosing chronic lymphocytic leukemia. METHODS: We compared in-house laboratory processes and results with those using the LST and B-CLPD T1 reagent tubes with, and without, blood film morphology. Outcome measures included concordance in classification results, and efficiency within the laboratory, that is, resource usage, staff time, unwanted events, and cost-consequences. RESULTS: There was 100% concordance between the classifications made with in-house flow cytometry and those with the BD OneFlow reagent tubes. Using BD OneFlow tubes required 13 hours less staff time per month (i.e. for 100 samples) than the in-house process. Sensitivity analyses explored the effects of uncertainties in the price of the BD OneFlow tubes and the prevalence of CLL and identified the thresholds at which laboratories might expect cost-savings from adopting the BD OneFlow system. Laboratory and clinical staff considered the BD OneFlow system to be safe and effective. CONCLUSIONS: Laboratories adopting the BD OneFlow system for classifying patients with suspected CLL can expect safe, efficient processes that can be cost saving if the discount on the list price, and prevalence of CLL (which will both vary between sites and countries), is within the thresholds suggested by the health economics sensitivity analysis. © 2019 International Clinical Cytometry Society.

Biofilm Challenge: Lactic Acid Bacteria Isolated from Bovine Udders versus Staphylococci.

Mastitis poses a considerable threat to productivity and to animal welfare on modern dairy farms. However, the common way of antibiotic treatment does not always lead to a cure. Unsuccessful cures can, among other reasons, occur due to biofilm formation of the causative agent. This has attracted interest from researchers to introduce promising alternative therapeutic approaches, such as the use of beneficial lactic acid bacteria (LAB). In fact, using LAB for treating mastitis probably requires the formation of a beneficial biofilm by the probiotic bacteria. The present study investigated the ability of five LAB strains, selected on the basis of results from previous studies, to remove and to replace pathogenic biofilms in vitro. For this purpose, Staphylococcus (S.) aureus ATCC 12,600 and two strains-S. xylosus (35/07) and S. epidermidis (575/08)-belonging to the group of coagulase negative staphylococci (CNS) were allowed to form biofilms in a 96-well plate. Subsequently, the LAB were added to the well. The biofilm challenge was evaluated by scraping off and suspending the biofilm cells, followed by a plate count of serial dilutions using selective media. All the LAB strains successfully removed the staphylococcal biofilms. However, only Lactobacillus (L.) rhamnosus ATCC 7469 and L. plantarum 2/37 formed biofilms of their own to replace the pathogenic ones.

Biofilm formation and adhesion to bovine udder epithelium of potentially probiotic lactic acid bacteria.

Mastitis is one of the most important diseases threatening modern dairy herds. The idea of fighting the disease through colonising the udder with lactic acid bacteria (LAB), thereby building a beneficial biofilm, is the base for a probiotic approach towards mastitis control. The purpose of this study was to screen 13 LAB strains (eleven wild strains, two ATCC strains) inhibitory to the growth of mastitis-causing pathogens for their in vitro ability to form a biofilm and to adhere to bovine glandular mammary epithelium in order to assess their probiotic potential. Furthermore, we aimed to gain knowledge about the chemical nature of the adhesins involved by subjecting the bacteria to various chemical and enzymatical pre-treatments. The biofilms were grown on hydrophilic glass and on hydrophobic polypropylene in de Man, Rogosa and Sharpe (MRS) broth and afterwards quantified with a crystal violet assay. Biofilm formation was observed in all strains. However, the extent strongly depended on the strain, surface charge and medium. The adhesion assay also revealed a strong strain dependency, but this trait was also present in all of the investigated LAB isolates. Depending on the strain, chemical or enzymatical pre-treatment revealed carbohydrate molecules as well as proteins and lipids to be crucial for the adhesion of LAB to epithelial cells. The seven strains showing the strongest biofilm formation and/or adhesion represent promising candidates for further investigation in order to develop a probiotic remedy for the treatment of mastitis. Still, their safety for consumers and patients as well as their capability to colonise the udder remain to be investigated in in vivo studies.

Age of platelet concentrates and time to the next transfusion.

BACKGROUND: Storage time of platelet (PLT) concentrates has been negatively associated with clinical efficacy outcomes. The aim of this study was to quantify the association between storage time of PLT concentrates and interval to the next PLT transfusion for different types of PLT components, stored for up to 7 days and transfused to transfusion-dependent hematooncology patients with thrombocytopenia. STUDY DESIGN AND METHODS: From a cohort of patients from 10 major Dutch hospitals, patients were selected whose transfusion patterns were compatible with PLT transfusion dependency due to hematooncologic disease. Mean time to the next transfusion and mean differences in time to the next transfusion for different storage time categories (i.e., fresh, <4 days; intermediate, 4-5 days; and old, >5 days) were estimated, per component type, using multilevel mixed-effects linear models. RESULTS: Among a cohort of 29,761 patients who received 140,896 PLT transfusions we selected 4441 hematooncology patients who had received 12,724 PLT transfusions during periods of PLT transfusion dependency. Transfusion of fresh, compared to old, buffy coat-derived PLTs in plasma was associated with a delay to the next transfusion of 6.2 hours (95% confidence interval [CI], 4.5-8.0 hr). For buffy coat-derived PLTs in PAS-B and -C this difference was 7.7 hours (95% CI, 2.2-13.3 hr) and 3.9 hours (95% CI, -2.1 to 9.9 hr) while for apheresis PLTs in plasma it was only 1.8 hours (95% CI, -3.5 to 7.1 hr). CONCLUSION: Our results indicate that the time to the next transfusion shortens with increasing age of transfused buffy coat-derived PLT concentrates. This association was not observed for apheresis PLTs.

Decoding subjective decisions from orbitofrontal cortex.

When making a subjective choice, the brain must compute a value for each option and compare those values to make a decision. The orbitofrontal cortex (OFC) is critically involved in this process, but the neural mechanisms remain obscure, in part due to limitations in our ability to measure and control the internal deliberations that can alter the dynamics of the decision process. Here we tracked these dynamics by recovering temporally precise neural states from multidimensional data in OFC. During individual choices, OFC alternated between states associated with the value of two available options, with dynamics that predicted whether a subject would decide quickly or vacillate between the two alternatives. Ensembles of value-encoding neurons contributed to these states, with individual neurons shifting activity patterns as the network evaluated each option. Thus, the mechanism of subjective decision-making involves the dynamic activation of OFC states associated with each choice alternative.

Where do all the red blood cells (RBCs) go? Results of a survey of RBC use in England and North Wales in 2014.

BACKGROUND: Knowledge of blood utilization can assist clinicians in directing patient blood management (PBM) initiatives and can facilitate demand planning by blood services. We describe a national study of red blood cell (RBC) utilization in England and North Wales in 2014. STUDY DESIGN AND METHODS: All hospitals that are supplied with blood components by NHS Blood and Transplant (NHSBT) were asked to provide data on the age and sex of all recipients of transfusions of RBCs, and the clinical indication for every unit transfused, for two separate weeks in 2014. Clinical indication categories were derived from those used in previous studies in an English region. Completeness of data collection was checked against NHSBT issue and wastage data. RESULTS: Data on 46,111 RBC units were collected, representing 73% of all RBCs issued by NHSBT during the weeks surveyed. A total of 67% of RBC units were transfused for a medical indication, with 27 and 6% being transfused for surgical and obstetric/gynecologic indications, respectively. For comparison, figures from a study in the North of England in 2009, on which this national study was based, showed that 64% of RBCs were transfused to medical patients. All but 20 units could be ascribed to a broad clinical heading, for example, "gastrointestinal bleeding." CONCLUSION: Our findings confirm the previous regional finding that the percentage of RBC units that are transfused to surgical patients in England and North Wales is now much lower than for medical patients and suggest that PBM initiatives should now focus on medical patients.

Capturing the temporal evolution of choice across prefrontal cortex.

Activity in prefrontal cortex (PFC) has been richly described using economic models of choice. Yet such descriptions fail to capture the dynamics of decision formation. Describing dynamic neural processes has proven challenging due to the problem of indexing the internal state of PFC and its trial-by-trial variation. Using primate neurophysiology and human magnetoencephalography, we here recover a single-trial index of PFC internal states from multiple simultaneously recorded PFC subregions. This index can explain the origins of neural representations of economic variables in PFC. It describes the relationship between neural dynamics and behaviour in both human and monkey PFC, directly bridging between human neuroimaging data and underlying neuronal activity. Moreover, it reveals a functionally dissociable interaction between orbitofrontal cortex, anterior cingulate cortex and dorsolateral PFC in guiding cost-benefit decisions. We cast our observations in terms of a recurrent neural network model of choice, providing formal links to mechanistic dynamical accounts of decision-making.

PARP1 expression, activity and ex vivo sensitivity to the PARP inhibitor, talazoparib (BMN 673), in chronic lymphocytic leukaemia.

In chronic lymphocytic leukemia (CLL), mutation and loss of p53 and ATM abrogate DNA damage signalling and predict poorer response and shorter survival. We hypothesised that poly (ADP-ribose) polymerase (PARP) activity, which is crucial for repair of DNA breaks induced by oxidative stress or chemotherapy, may be an additional predictive biomarker and a target for therapy with PARP inhibitors.We measured PARP activity in 109 patient-derived CLL samples, which varied widely (192 - 190052 pmol PAR/106 cells) compared to that seen in healthy volunteer lymphocytes (2451 - 7519 pmol PAR/106 cells). PARP activity was associated with PARP1 protein expression and endogenous PAR levels. PARP activity was not associated with p53 or ATM loss, Binet stage, IGHV mutational status or survival, but correlated with Bcl-2 and Rel A (an NF-kB subunit). Levels of 8-hydroxy-2'-deoxyguanosine in DNA (a marker of oxidative damage) were not associated with PAR levels or PARP activity. The potent PARP inhibitor, talazoparib (BMN 673), inhibited CD40L-stimulated proliferation of CLL cells at nM concentrations, independently of Binet stage or p53/ATM function.PARP activity is highly variable in CLL and correlates with stress-induced proteins. Proliferating CLL cells (including those with p53 or ATM loss) are highly sensitive to the PARP inhibitor talazoparib.

ABO-incompatible cardiac transplantation in pediatric patients with high isohemagglutinin titers.

BACKGROUND: ABO-incompatible (ABOi) cardiac transplantation is now used widely in infants with isohemagglutinin titers <1:4, but there is increasing evidence that ABOi transplantation can also be used in children with significantly higher titers. We reviewed our high-titer ABOi transplants and report our results here. METHODS: Patients who underwent ABOi cardiac transplantation from 2000 to 2013 with pre-existing isohemagglutinin titers of ≥1:16 were identified from departmental databases. Outcomes were reviewed using medical and laboratory records. RESULTS: Thirty patients underwent ABOi cardiac transplantation between 2000 and 2013. Twelve (40%) had pre-transplant isohemagglutinin titers of ≥1:16 and were included for further study. Median age was 14.9 (range 9.8 to 107.3) months and median weight was 9.6 (range 7.6 to 25) kg. Five (42%) were male. Pre-transplant diagnosis was cardiomyopathy in 8 of 12 (67%) and congenital heart disease in 4 of 12 (33%). Highest pre-transplant isohemagglutinin titer was 1:256 in 2 patients. Four patients (33%) had early antibody-mediated rejection (AMR), all within 15 days post-transplant. Management included use of rituximab, bortezomib, immunoadsorption and eculizumab. Three patients died but no deaths were associated with high isohemagglutinin titers. CONCLUSIONS: ABOi cardiac transplantation in patients with isohemagglutinin titers ≥1:16 is possible. AMR may occur early and immunoadsorption has proven effective at decreasing antibody titers.

The Role of Prefrontal Cortex in Working Memory: A Mini Review.

A prominent account of prefrontal cortex (PFC) function is that single neurons within the PFC maintain representations of task-relevant stimuli in working memory. Evidence for this view comes from studies in which subjects hold a stimulus across a delay lasting up to several seconds. Persistent elevated activity in the PFC has been observed in animal models as well as in humans performing these tasks. This persistent activity has been interpreted as evidence for the encoding of the stimulus itself in working memory. However, recent findings have posed a challenge to this notion. A number of recent studies have examined neural data from the PFC and posterior sensory areas, both at the single neuron level in primates, and at a larger scale in humans, and have failed to find encoding of stimulus information in the PFC during tasks with a substantial working memory component. Strong stimulus related information, however, was seen in posterior sensory areas. These results suggest that delay period activity in the PFC might be better understood not as a signature of memory storage per se, but as a top down signal that influences posterior sensory areas where the actual working memory representations are maintained.

A hierarchy of intrinsic timescales across primate cortex.

Specialization and hierarchy are organizing principles for primate cortex, yet there is little direct evidence for how cortical areas are specialized in the temporal domain. We measured timescales of intrinsic fluctuations in spiking activity across areas and found a hierarchical ordering, with sensory and prefrontal areas exhibiting shorter and longer timescales, respectively. On the basis of our findings, we suggest that intrinsic timescales reflect areal specialization for task-relevant computations over multiple temporal ranges.

Familial pseudohyperkalemia in blood donors: a novel mutation with implications for transfusion practice.

BACKGROUND: Familial pseudohyperkalemia (FP) is a dominantly inherited condition in which red blood cells (RBCs) have an increased cold-induced permeability to monovalent cations. Potassium leaks into the supernatant of all stored blood with time, but FP RBCs leak potassium more rapidly. We investigated two unrelated blood donors whose RBC donations demonstrated unexpectedly high potassium after 5 and 6 days' storage. We matched the observed pattern of RBC cation leak to a previously recognized family with FP (FP-Cardiff) and investigated the likely cause with targeted DNA analysis. STUDY DESIGN AND METHODS: Cation leakage from the donor RBCs and from standard donor units was measured. DNA analysis of donors and family members with FP-Cardiff was performed. Allele frequencies were obtained from human variation databases. RESULTS: Both implicated donors were found to have increased cold-induced potassium leak identical in pattern to affected members of the family with FP-Cardiff. We found a heterozygous substitution Arg723Gln in the ATP-binding cassette, Subfamily B, Member 6 protein that segregated with FP in the Cardiff family and was also present in both blood donors. Arg723Gln is listed in human variation databases with an allele frequency of approximately 1:1000. CONCLUSIONS: We describe a novel FP mutation that may affect 1:500 European blood donors and causes rapid loss of potassium from stored RBCs. This finding has implications for neonates and infants receiving large-volume RBC transfusions. Genomic screening of donors could be used to identify donors with this mutation and potentially improve the quality and safety of donor units.