Oliveira, Jennifer L.

Pulse oximetry is routinely used in the newborn nursery for clinical monitoring and to detect critical congenital heart disease. The differential diagnoses for reduced peripheral oxygen saturation in an infant include congenital heart disease, respiratory distress syndrome, transient tachypnea of the newborn, persistent pulmonary hypertension of the newborn, meconium aspiration syndrome, pneumonia, pneumothorax, and sepsis. The diagnostic evaluation for neonatal hypoxemia can be invasive and expensive. When this evaluation is unrevealing, other interventions may be tried without clear benefit to the patient, including, but not limited to, supplemental oxygen. Therefore, it is important to consider alternative, albeit rare, diagnoses, including hemoglobinopathies with abnormal oxygen binding properties. Mutations in the structure of alpha- and beta-globin chains can alter the affinity of hemoglobin for oxygen, and changes in oxygen affinity may result in changes in the oxygen saturation detected by pulse oximetry. These changes may or may not be of clinical significance. This case report describes Hemoglobin Sunshine Seth, a rare low-oxygen-affinity hemoglobin variant presenting as reduced peripheral oxygen saturation in an otherwise well-appearing infant male.

Key points Theoretical models suggest there is no benefit of high affinity haemoglobin to preserve maximal oxygen uptake in acute hypoxia but the comparative biology literature has many examples of species that are evolutionarily adapted to hypoxia and have high affinity haemoglobin. We studied humans with high affinity haemoglobin and compensatory polycythaemia. These subjects performed maximal exercise tests in normoxia and hypoxia to determine how their altered haemoglobin affinity impacts hypoxic exercise tolerance. The high affinity haemoglobin participants demonstrated an attenuated decline in maximal aerobic capacity in acute hypoxia. Those with high affinity haemoglobin had no worsening of pulmonary gas exchange during hypoxic exercise but had greater lactate and lower pH than controls for all exercise bouts. High affinity haemoglobin and compensatory polycythaemia mitigated the decline in exercise performance in acute hypoxia through a higher arterial oxygen content and an unchanged pulmonary gas exchange. AbstractThe longstanding dogma is that humans exhibit an acute reduction in haemoglobin (Hb) binding affinity for oxygen that facilitates adaptation to moderate hypoxia. However, many animals have adapted to high altitude through enhanced Hb binding affinity for oxygen. The objective of the study was to determine whether high affinity haemoglobin (HAH) affects maximal and submaximal exercise capacity. To accomplish this, we recruited individuals (n = 11, n = 8 females) with HAH (P50 = 16 ± 1 mmHg), had them perform normoxic and acute hypoxic (15% inspired oxygen) maximal exercise tests, and then compared their results to matched controls (P50 = 26 ± 1, n = 14, n = 8 females). Cardiorespiratory and arterial blood gases were collected throughout both exercise tests. Despite no difference in end‐exercise arterial oxygen tension in hypoxia (59 ± 6 vs. 59 ± 9 mmHg for controls and HAH, respectively), the HAH subjects’ oxyhaemoglobin saturation () was ∼7% higher. Those with HAH had an attenuated decline in maximal oxygen uptake () (4 ± 5% vs. 12 ± %, p < 0.001) in hypoxia and the change in between trials was related to the change in (r = −0.75, p < 0.0001). Compared to normoxia, the controls’ alveolar‐to‐arterial oxygen gradient significantly increased during hypoxic exercise, whereas pulmonary gas exchange in HAH subjects was unchanged between the two exercise trials. However, arterial lactate was significantly higher and arterial pH significantly lower in the HAH subjects for both exercise trials. We conclude that HAH attenuates the decline in maximal aerobic capacity and preserves pulmonary gas exchange during acute hypoxic exercise. Our data support the comparative biology literature indicating that HAH is a positive adaptation to acute hypoxia.

Background: Molecular genetic testing is increasingly utilized in clinical care, typically with peripheral blood as the preferred specimen. Despite the prevalence of therapeutic blood transfusions, whether donor DNA is present in a sufficient quantity to interfere with recipient genetic testing has not been systematically studied. Microchimerism secondary to transfusion of blood products with donor leukocytes has been well-documented in trauma patients receiving whole blood; however, most medical centers currently transfuse leukoreduced (LR) red blood cell products for non-trauma patients. The degree of leukoreduction varies among centers, but to meet AABB standards must be &lt;5x106 white blood cells (WBC) in 95% of units tested. We sought to determine what quantity, if any, of infused LR or non-LR (NLR) products leads to detectable microchimerism that may impact genetic test results. Methods: We performed an in vitro spiking study utilizing four whole blood units collected from different anonymous donors. Three were leukoreduced at varying levels in order to establish a LR (per our institutional guidelines and standards), a partially leukoreduced (PLR) and a NLR unit, which were then considered "donors". The 4th unit was divided to generate two separate "recipients". The first half was left untreated simulating an immunocompetent recipient while the other was leukoreduced to mimic a leukopenic recipient. Based on a 70 kg patient, we calculated the volume of blood from each "donor" to mix with aliquots of each "recipient" to represent a transfusion of 2, 5, or 16 units, with 2 units corresponding to a double apheresis red blood cell (RBC) transfusion and 16 units corresponding to a near total volume transfusion. DNA was extracted from each individual unit as well as all "transfused" combinations within 24 hours of mixing. Chimerism analysis was then performed by STR analysis using the GlobalFiler PCR amplification kit followed by ChimerMarker analysis software. Results: None of the LR units, despite volume transfused, revealed any level of microchimerism in either the immunocompetent or leukopenic "recipients". The PLR transfused combinations displayed levels ranging from 0.14% to 1.52% of donor chimerism for the immunocompetent "recipient", which is below the limit of detection for most clinical assays evaluating germline genetic variation, and 6.3% to 27.78% of donor chimerism for the leukopenic "recipient", which would be expected to impact a subset of clinical genetic assays. The NLR transfused combinations displayed levels ranging from 13.28% to 95.66% of donor chimerism. Discussion:In vitro "transfusion" of LR RBCs into simulated immunocompetent or leukopenic samples does not lead to detectable donor DNA. However, "transfusion" of PLR and NLR units in an in vitro model reveals significant levels of microchimerism dependent on volume transfused and immune status of the "recipient" which implies possible risk for impact on clinical genetic tests. The minimum time required for clearance of donor leukocytes in the recipient is unknown; we were unable to fully evaluate this and other variables in our in vitro system, but follow-up in vivo studies addressing this question are planned. Disclosures No relevant conflicts of interest to declare.

Introduction: Globin gene sequencing has long been impeded by repetitive regions, homology and structural variation. Currently, long-read sequencing technology has been limited by high cost and error rate. These challenges can be mitigated by sample multiplexing of targeted capture sequencing and the use of consensus reads, respectively. This ongoing study analyzes the utility of long range sequencing technology in identifying historically problematic beta globin cluster mutations. Materials and methods: Long range sequencing was performed on complex beta globin gene cluster cases utilizing the Sequel platform (Pacific Biosciences, Menlo Park, California, United States). Sample input was 1 microgram of DNA extracted from whole blood. Circular Consensus Sequence (CCS) FASTQ sequences files were mapped to reference genome (GRCh37/hg19) using NGMLR, followed by annotation of variants using a custom bioinformatics workflow. Comparison to multiplex ligation-dependent probe amplification (MLPA), Sanger sequencing, array CGH, short-range NGS (300 bp), hemoglobin protein, and clinical data was performed. Results: CCS read length varied from 1 to 10 kb, average 3.5. Analysis of the beta globin cluster region showed impressive superiority and comprehensiveness to Sanger, MLPA, array CGH and short range sequencing technology: 1) single nucleotide variants (SNVs) were identified to a sensitivity and specificity of 99.5%; 2) large structural variants (SVs) such as large deletions, duplications, insertions, crossovers and fusions spanning many kilobases were characterized in the heterozygous, homozygous and compound heterozygous state to a precise genomic coordinate (table 1); 3) phasing SNVs identified Hb S haplotypes (Central African region (CAR), Benin, Senegal, Arab-Indian and Cameroon). Conclusion: 1) Long range sequencing holds significant promise in genotyping hemoglobin disorders. This method improves efficiency with potential for a single test offering with increased resolution, particularly in large deletion analysis. Complex cases greatly benefited from improved range and resolution. 2) The decreased requirement of blood volume for extensive testing is of particular interest for the pediatric population. 3) Genotyping of Hb S patients detected by positive newborn screening will help predict need for prophylaxis or therapy by assessing variant zygosity, phasing and haplotypes. In conclusion, we believe that long range sequencing has immense potential to contribute extensively to thalassemia and hemoglobinopathy diagnostics and is far superior to the currently available technologies for beta globin cluster analysis. Disclosures Jen: Celgene: Employment.

Background: Genetic variants resulting in quantitative defects in the production of α-spectrin are associated with autosomal recessive hereditary spherocytosis (HS). Because erythroid cells produce α-spectrin in a 3-4:1 ratio in relation to β-spectrin, one defective allele is typically well-tolerated and a single null allele combined with a second partially defective allele may display a sub-clinical phenotype. Protein expression can be reduced by nonsense, frameshift, missense or splicing variants but reported large deletion events are extraordinarily rare (n = 1). Splicing variants include the low expression alleles αLELY - Low Expression LYon (SPTA1:c.6531-12C>T, p.?) and αLEPRA-Low Expression PRAgue (SPTA1:c.4339-99C>T, p.?) which reduce protein expression by 50% and 16%, respectively. Here, we present a family study with a whole gene SPTA1 deletion that characterizes the patient phenotype when a full gene mutation is co-inherited with the αLEPRA and αLELY low expression alleles. Methods: The 6 month-old male proband had a history of congenital Coombs negative hemolytic anemia requiring transfusion from 3 months of age and in whom a red cell membrane disorder was clinically suspected. Pretransfusion CBC and peripheral blood smear results were unknown. Transfused CBC indices were as follows: RBC 4 x 1012/L, HGB 11 g/dL, MCV 76 fL, MCH 27 pg, MCHC 36 g/dL and a reticulocyte count of 1.8%. The proband's mother, of Cuban descent, and father, of European descent, had no history of anemia or HS. Targeted high throughput sequencing of genes related to hereditary hemolytic anemia was performed for the detection of single nucleotide variants (SNVs) and small insertion/deletion variants (indels). Relative quantitative real time PCR (RT-PCR) was utilized to confirm large structural variants. Results: Sequencing identified a large heterozygous deletion that spanned the entire SPTA1 gene (NC_000001.11:g.(?_158656337)_(158581024_?) in the proband and his mother. In addition, the proband had inherited hemizygous αLEPRA from his father. The mother had hemizgous αLELY. The father showed heterozygous αLEPRA and no other SPTA1 variants (Table 1). Conclusion: To our knowledge, only Iolascon et al in 2011 has reported a SPTA1 gene large deletion (SpectrinExeter, exon 11-exon 12 deletion, loss of 83 amino acids) which resulted in a structurally abnormal protein and ellipto-poikilocytosis phenotype when in trans to αLELY. Our current case is the first reported SPTA1 full gene deletion and our family study allows comparison of the effects of coinheritance of the low expression alleles αLEPRA and αLELY. When in combination with complete absence of the SPTA1 gene in trans configuration, αLELY manifests in subclinical effects and αLEPRA causes a recessive HS phenotype, which resulted in severe anemia. This contrast further demonstrates that, unlike αLEPRA, αLELY does not decrease the α-spectrin concentration sufficiently to contribute to the baseline phenotype regardless of the severity of the second allele mutation for quantitative disorders such as HS. Disclosures No relevant conflicts of interest to declare.

Background: Voxelotor (GBT440) is a small molecule allosteric effector with high specificity for hemoglobin (Hb) that inhibits Hb S polymerization by increasing hemoglobin oxygen affinity. Developed as an oral, once-daily medication, it is undergoing phase 3 randomized clinical trials in sickle cell disease patients. Therapeutic monitoring of Hb quantitative fractions is routine in sickle cell disease patients to assess medication and transfusion effects and future treatment requirements. In the clinical laboratory, some therapies can alter the Hb fraction percentages or characteristic protein migration/elution patterns and can mimic complex hemoglobinopathy disorders causing misinterpretation or unnecessary additional testing. We present the effects of voxelotor on hemoglobin identification/monitoring testing in multiple testing platforms. Methods: A whole blood anticoagulated sample from a male patient who was undergoing treatment for sickle cell disease was received for routine hemoglobin testing. Five additional samples with similar features were also received from three male patients (age range of all patients was 18 to 22 years) with sickle cell disease. Hemoglobin protein analysis was performed using standard methods including cation-exchange high performance liquid chromatography (HPLC), capillary electrophoresis (CE), isoelectric focusing (IEF), intact globin chain mass spectrometry (MS), sickle solubility and hemoglobin stability studies. DNA sequencing of the alpha (HBA1/HBA2) and beta globin (HBB) genes was performed on one sample. Results: CE (initial and 50:50 mix, figures 1A and 1B, respectively) revealed a Hb S peak with a shoulder and additional small peaks at position 203 (D zone) and 234 (cusp of zones E/A2). In some cases the 234 peak interfered with instrument designation of the A2 peak (50:50 mix with normal) and shifted the Hb S peak into the E zone which risks variant misidentification (figure 1C). Our laboratory overcame this limitation by substituting the normal sample with beta thalassemia trait to enhance the Hb A2 peak after mixing. HPLC tracings (figure 1D) showed a duplex peak pattern in the D and S windows with separate peak quantification percentages (index case showed elution at 4.18 and 4.37 minutes with 14.9% and 66.4%, respectively). The dual peaks detected by HPLC partially mimicked compound Hb S/D-Punjab. IEF (figure 1E) showed additional bands at -4.7, and -11.5 (Schneider-Barwick ratios). The additional peaks identified by CE and IEF mimicked an alpha chain hemoglobin variant; however, the expected hybrid patterns were atypical prompting further investigation. Sickle solubility was positive, heat stability studies were negative and mass spectrometry did not definitively detect abnormal peaks other than βS. DNA sequencing of the alpha and beta globin genes did not reveal abnormalities other than homozygous Hb S. Similar hemoglobin patterns were identified in all samples tested. Conclusion: Voxelotor treatment in sickle cell patients results in a distinctive pattern alteration in hemoglobin testing. Methods may not give accurate variant percentage estimation and the treatment may result in shifts in variant mobility causing erroneous laboratory results. Novel therapies are increasing in the treatment of hemoglobin disorders and medication effect should be a consideration when atypical patterns are encountered in the laboratory. Knowledge of these artifacts by clinicians and laboratorians is paramount to avoid erroneous diagnosis, unnecessary additional testing and inaccurate Hb variant quantitation for monitoring purposes. Notification of current treatment regimens to testing facilities is highly recommended in these patients. Figure 1 Disclosures No relevant conflicts of interest to declare.

Arterial oxygen tension and oxyhemoglobin saturation ([Formula: see text]) decrease in parallel during hypoxia. Distinguishing between changes in oxygen tension and oxygen content as the relevant physiological stimulus for cardiorespiratory alterations remains challenging. To overcome this, we recruited nine individuals with hemoglobinopathy manifesting as high-affinity hemoglobin [HAH; partial pressure at 50% [Formula: see text] (P50) = 16 ± 0.4 mmHg] causing greater [Formula: see text] at a given oxygen partial pressure compared with control subjects ( n = 12, P50 = 26 ± 0.4 mmHg). We assessed ventilatory and cardiovascular responses to acute isocapnic hypoxia, iso-oxic hypercapnia, and 20 min of isocapnic hypoxia (arterial Po2 = 50 mmHg). Blood gas alterations were achieved with dynamic end-tidal forcing. When expressed as a function of the logarithm of oxygen partial pressure, ventilatory sensitivity to hypoxia was not different between groups. However, there was a significant difference when expressed as a function of [Formula: see text]. Conversely, the rise in heart rate was blunted in HAH subjects when expressed as a function of partial pressure but similar when expressed as a function of [Formula: see text]. Ventilatory sensitivity to hypercapnia was not different between groups. During sustained isocapnic hypoxia, the rise in minute ventilation was similar between groups; however, heart rate was significantly greater in the controls during 3 to 9 min of exposure. Our results support the notion that oxygen tension, not content, alters cellular Po2in the chemosensors and drives the hypoxic ventilatory response. Our study suggests that in addition to oxygen partial pressure, oxygen content may also influence the heart rate response to hypoxia.NEW & NOTEWORTHY We dissociated the effects of oxygen content and pressure of cardiorespiratory regulation studying individuals with high-affinity hemoglobin (HAH). During hypoxia, the ventilatory response, expressed as a function of oxygen tension, was similar between HAH variants and controls; however, the rise in heart rate was blunted in the variants. Our work supports the notion that the hypoxic ventilatory response is regulated by oxygen tension, whereas cardiovascular regulation may be influenced by arterial oxygen content and tension.

Abstract Introduction Myelodysplastic syndromes (MDS) are heterogeneous myeloid disorders characterized by dysplasia in one or more hematopoietic cell lines, peripheral cytopenia(s), and distinct cytogenetic abnormalities. The presence of certain cytogenetic abnormalities [e.g. 7/del(7q), -5/del(5q), 13/del(13q), i(17p)], in the setting of unexplained persistent cytopenia, has been considered presumptive evidence of MDS, despite definitive morphologic features of MDS. Conversely, chromosomal abnormalities such as isolated 20q- are not considered definitive evidence for MDS, in the absence of dysplasia. Based on our previous findings, patients with isolated 20q- without morphologic features of a myeloid neoplasm have varied clinical outcomes (Jawad MD et al. Am J Hematol.2016). In this study, we investigate the frequency of recurrent somatic gene mutations in these patients, and their relationship to progression to a myeloid neoplasm. Methods We retrospectively reviewed the bone marrow pathology reports of patients evaluated at our institution from 01/2005 to 09/2015 who had isolated 20q- in at least 2 of 20 metaphases. Patients with isolated 20q- and without myeloid neoplasms were included in the study, along with medical record review. A 35-gene next generation sequencing (NGS) panel (OncoHeme) targeting myeloid neoplasms was performed on available archived bone marrow aspirate pellets. Statistical analyses were performed using JMP Pro software version 13. Parametric (t-test) or nonparametric tests such as the Fisher-exact test, chi-square test, or Wilcoxon rank-sum test, were utilized as appropriate for test variables. Statistical significance was based on a 2-sided significance level of .05. Kaplan-Meier analysis was used for analyzing time to progression to myeloid neoplasms and progression-free survival (i.e. time to progression to myeloid neoplasms or death from any cause). Results Fifty-six (42 males, 14 females) patients with isolated 20q- were identified. The average percentage of 20q- was 38.5 % (±29.3). The median age was 68 years (range: 44-90) and the median hemoglobin (Hb), absolute neutrophil count (ANC) and platelet count (Plt) were 11.7 g/dL (range: 8.3-15.1), 2.7 x 10(9)/L (range: 0.6-9.4) and 138 x 10(9)/L (range: 16-392), respectively. The indications for bone marrow biopsies ranged from cytopenia (21), multiple myeloma (20), non-Hodgkin lymphoma (10), amyloidosis (2), CLL (2) and transplant donor evaluation (1). Twenty-three patients harbored pathogenic mutations (15 had one mutation, 1 had two mutations and 7 had three mutations). The identified pathogenic mutations included ASXL1 (8), TET2 (8), SRSF2(3),PHF6 (2), SF3B1 (2), CBL (2), U2AF1 (2), IDH1 (1), IDH2 (1), BCOR (1), JAK2 (1), PTPN11(1), TP53 (1) and RUNX1 (1). Nine patients (16.1%) progressed to myeloid neoplasms (5 MDS, 2 acute myeloid leukemia, 2 chronic myeloid neoplasm-not otherwise specified) at a median follow-up of 36.7 months (range: 1.9-57.4). Of these 9 patients, 5 had one mutation (BCOR, TET2, DNM3TA, CBL, IDH2), 1 had two mutations (SF3B1/CBL) and 3 had three mutations (ASXL1/IDH1/SRSF2,DNM3TA/PTPN11/TET2, PHF6/TET2/TET2). In contrast, only 29.8% of non-progressed cases showed at least 1 mutation. Kaplan-Meier analysis demonstrated the presence of genetic mutations in patients with isolated 20q- carried significantly higher chance of progression to myeloid neoplasms (p<.05, Figure 1A and 1B). However, the number of genetic mutations was not predictive of progression in our relatively small study cohort (p=.66). There was no significant difference between those who did and did not progress with respect to age, gender, Hb, ANC, Plt, 20q- or mutational allele burden. Conclusions Most of the patients with isolated 20q- and without morphologic features of a myeloid neoplasm did not harbor myeloid neoplasm associated gene mutations and further did not develop a myeloid neoplasm during the course of our study. Among patients with pathogenic mutations, nearly one-third showed progression to a myeloid neoplasm. Of the clinical and laboratory variables, the presence of genetic mutation is a significant risk factor for progression to a myeloid neoplasm. This study revealed the underlying molecular heterogeneity of isolated 20q- in the absence of morphologic features of a myeloid neoplasm, and underscored the prognostication value of genetic mutation analysis in these cases. Disclosures No relevant conflicts of interest to declare.

Abstract Background: The 2016 revision to the World Health Organization (WHO) classification of myeloid neoplasms has specifically categorized germline mutations that are associated with myeloid clonal evolution (Arber et al. Blood 2016). This group consists of myeloid neoplasms with an isolated germline predisposition (CEBPA, DDX41), myeloid neoplasms associated with congenital thrombocytopenia (ETV6, RUNX1, ANKRD26) and germline myeloid neoplasms with multi-organ dysfunction (GATA2, chromosomal breakage disorders, telomere biology disorders etc). We carried out this study to describe the clinical spectrum of germline disorders with predisposition to myeloid neoplasms as categorized by the 2016 WHO classification revision. Methods: After Institutional Review Board (IRB) approval, the adult and pediatric bone marrow failure syndrome database (1990-2016) and the electronic medical record were queried for germline disorders involving GATA2, CEBPA, DDX41, ETV6, RUNX1, ANKRD26, Down syndrome and Noonan syndrome. Chromosomal breakage assays (Diepoxybutane/Mitomycin-C), flow-fluorescent in-situ hybridization (FISH) for telomere length assessment, Fanconi anemia complementation assays and Sanger/Next Generation sequencing (NGS) for the aforementioned germline disorders with myeloid predisposition were carried out in Clinical Laboratory Improvement Amendments (CLIA)-certified laboratories. These disorders were then classified based on the 2016 WHO classification revision. Results : 54 individuals (37 families) were included in the study. Eleven (20%) patients belonging to 5 families were identified as having germline mutations with a preexisting platelet disorder: ETV6 (n=1), ANKRD26 (n=5), RUNX1 (n=5). Forty-three (79%) patients (32 families) had inherited syndromes with multi-organ dysfunction: GATA2 (n=11, 26%), bone marrow failure syndromes (n=14, 33%) and telomere biology disorder (n=14, 33%). There was one patient with neurofibromatosis with a germline PTPN11 mutation who developed juvenile myelomonocytic leukemia, while there were three patients with Down syndrome; 2 with transient abnormal myelopoiesis and one who developed acute megakaryocytic leukemia. The clinical phenotype, prevalence and characteristics of myeloid clonal evolution and outcomes are presented in Table 1. No patients with germline CEBPA or DDX41 mutations were identified. Patients with germline platelet disorders did not have any prominent non-hematological manifestations. Erythrocytosis (20%) with long-standing thrombocytopenia (100%) was a unique feature associated with ANKRD26 mutations. Non-hematologic clues such as human papillomavirus (HPV)-driven warts, primary lymphedema (Emberger syndrome) and frequent atypical infections with monocytopenia were seen in patients with germline GATA2 mutations, and preceded myeloid clonal evolution (morphologic, cytogenetic and molecular). Notably, the age at presentation and penetrance of myeloid transformation was variable, with individuals from the same family developing symptoms during the first decade of life and others remaining asymptomatic to date (fifth decade). Somatic ASXL1 mutations were detected in all 3 (100%) patients with GATA2 mutations and in one patient with ANKRD26 mutation that developed myeloid clonal evolution. In our study myeloid clonal evolution was seen in 40% with RUNX1 mutations, 27% with GATA2 mutations, and 20% with ANKRD26 mutations. We could not calculate the same for bone marrow failure syndromes as the total number of cases seen are still being assessed. Outcomes with allogeneic stem cell transplantation were favorable in appropriately selected patients (Table 1). Conclusion : The 2016 WHO revision to the classification of myeloid neoplasms highlights the importance of recognition and molecular characterization of germline mutations (syndromic and non-syndromic) with risk for myeloid clonal evolution. While some of these disorders (GATA2, Fanconi anemia, telomere biology disorders) may have important non-hematological clues, many present with isolated thrombocytopenia (RUNX1, ETV6). The age and frequency of myeloid evolution is highly variable. Acquisition of somatic ASXL1 mutations at the time of clonal myeloid transformation highlights the role of epigenetic dysregulation in disease evolution. Disclosures Kenderian: Novartis: Patents & Royalties, Research Funding.