Botero, Juliana Perez

Abstract Background Hip and knee arthroplasty (THA and TKA), in general, pose a high risk for venous thromboembolism (VTE), and pharmacologic VTE prophylaxis is often strongly recommended. In patients (pt) with hemophilia undergoing THA/TKA, given the underlying bleeding diathesis, the routine use of pharmacologic VTE prophylaxis is controversial. In this study, we report THA/TKA outcomes in pt with hemophilia in our institution. Methods Retrospective chart review of Mayo Comprehensive hemophilia center pt undergoing THA and TKA. Medical records were reviewed for objectively documented VTE for up to 3 months after surgery. Results 42 consecutive pt with hemophilia A (n=38) or B (n=4) underwent 71 operations: THA (n=32) and TKA (n=39) over a period of 39 years. All pt received compression stockings up to 6 weeks after surgery; 6/71 (8.4%) received sequential intermittent compression and 2/71 (2.8%) received postoperative low molecular weight heparin (LMWH). Symptomatic femoral vein DVT occurred in 1/42 pt (2%); (1/71, 1.4% of operations (1.4%)), 10 days after THA for traumatic hip fracture and after the LMWH was discontinued. The patient was subsequently found to be heterozygous for the factor V Leiden gene mutation. For up to 3 months after surgery, there were no additional cases of symptomatic DVT. There was no unexpected bleeding in the 2 patients receiving LMWH. Conclusion In this this study, routine use of compression stockings without the use of pharmacologic prophylaxis resulted in a low rate of symptomatic VTE in patients with hemophilia. This may be similar to the incidence in the general population receiving LMWH (Heit, JA et al Annals of Internal Medicine 2000) A limited sample size precludes definitive recommendations for practice. For appropriate high risk patients, limited use of pharmacologic prophylaxis may still be important. 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.

Abstract Background: Platelet transfusions are important for supporting patients with hematologic disorders. Refractoriness to platelet transfusions may lead to serious complications and pose a challenge to clinical management. A variety of laboratory strategies to optimize transfusion support in this population are being used; however, data on clinical correlation and success of these interventions is limited. We report the laboratory testing, transfusion yield, and clinical correlation in a cohort of patients receiving cross-matched platelet units. Methods: All consecutive adult patients refractory to platelet transfusions (failure to increment platelet count by 10 x 10(9) times two) with platelet crossmatch performed between June 2014 and April 2016 at our institution were included. Detailed clinical information, laboratory data of the crossmatch results, and Single Antigen Bead (SAB; Luminex) for each platelet unit cross-matched was retrospectively collected. Mean fluorescence intensity (MFI) of antibodies directed towards donor platelet HLA antigens identified through SAB were grouped into zones according to previously validated laboratory data: green zone (<4,000 MFI), yellow zone (4000-10000) and red zone (>10,000). Adequate transfusion yield was defined as an absolute increase of at least 10 x 10((9)/L platelets on a post-transfusion (i.e., within 1 hour) sample. Patients with major bleeding per International Society on Thrombosis and Haemostasis (ISTH) criteria, palpable splenomegaly, fever during transfusion, DIC, active sepsis, or antibodies directed against human platelet antigens were excluded from the final analysis. Importantly, the Hematologist and Pathologist were blinded to the other's data until collection was completed. Data analysis correlating adequate transfusion yield and laboratory parameters was performed. Results: 22 patients (72% female) met our study criteria. All patients had a hematologic malignancy with prolonged pancytopenia after chemotherapy, 4 (18%) had undergone allogeneic bone marrow transplantation. A total of 422 platelet cross-matches were performed, with 17 patients ultimately receiving 46 cross-matched units. The indication for transfusion was: prophylactic 35 (76%), bleeding 4 (9%) and peri-procedural 7 (15%). Ten (22%) transfusion events were excluded: splenomegaly 3, fever 4 and active severe bleeding 2. In one case a post transfusion platelet count was not performed. The overall success rate of transfusion was 64% (23/36). All transfusions leading to an adequate yield had a negative crossmatch. Of the 13 ineffective transfusions, 2 had a positive crossmatch. Based on single antigen MFI assignment, 26 (74%) donor units were classified as green zone, 8 (23%) yellow and 1 (3%) red. The success rates according to the single MFI zone assignment are presented in Table 1. These MFI-defined assignments were predictive of clinically successful transfusions. Conclusion: Selection of appropriate donor platelet units in refractory patients is a challenge that is managed in a variety of ways. While crossmatching is sometimes necessary, a strategy of antigen-avoidance can dramatically increase the identification of potentially effective platelet units for many patients. Understanding of how to navigate HLA antibody data is essential for identifying which HLA antigens should be avoided. Based on these data, in general, our practice is to avoid transfusing a platelet when there is a donor specific antibody of 8,000 MFI or greater. Furthermore, in our dataset there were two patients with both successful and unsuccessful transfusions after receiving crossmatch-negative units with green zone assignment. This finding highlights the limitations of laboratory testing and emphasizes the importance of post-transfusion platelet counts for continuously improving the platelet support of each immune-refractory patient. Disclosures No relevant conflicts of interest to declare.

Introduction Patients with inherited and acquired platelet disorders (PD) frequently present with thrombocytopenia and/or mucocutaneous bleeding. Diagnosis of PDs relies on both clinical and laboratory investigation, which encompasses both routine and esoteric platelet testing. The former includes platelet indices, light transmission aggregation (LTA) and platelet function analyzer (PFA-100). The latter includes platelet glycoprotein (GP) assessment by flow cytometry and platelet transmission electron microscopy (PTEM). Several recent studies have demonstrated limited sensitivities of routine platelet testing. It is uncertain if a combination of both routine and esoteric testing can vastly improve the sensitivity. Our goal is to assess the value of platelet esoteric testing and the ultimate sensitivity of laboratory platelet testing in diagnosing PDs. Methods Patients (between year 2012 and 2015) with a known or suspected inherited or acquired platelet disorders were recruited for platelet routine and esoteric testing. Patients' clinical features including ISTH bleeding assessment tool (BAT) scores, platelet count, LTA, PFA-100 ADP (CADP) and epinephrine (CEPI) cartridge closure times, GP expression by flow cytometry and PTEM were performed. All clinical and laboratory variables were collected and statistically analyzed. Results A total of 69 patients (51 females; median age 40 years; range: 8 months to 76 years) were enrolled to this cohort study. By retrospective chart review, 34 patients (49%) had a positive ISTH-BAT score (range 0 to 16). The most common bleeding manifestations (on any degree of severity) were cutaneous bleeding present in 53% of patients (n=37), menorrhagia in 47% of females (n=24), epistaxis in 36% (n=25) and postoperative bleeding in 35% (n=24). Joint, muscle and CNS hemorrhage were the least frequent with 7%, 6% and 1% of patients reporting bleeding in these sites. A total of 22 patients (32%) had thrombocytopenia at the time of their evaluation. Fifty-eight patients (84%) had platelet aggregation studies and of those 15 (26%) had an abnormal study. PFA-100 was performed in 57 patients (83%) of whom 42% (n=24) had prolonged closure times with either ADP or epinephrine. PTEM was performed on all samples. Twenty-seven patients (39%) had abnormal platelet structure including 17 patients who had dense granule deficiency. GP by flow cytometry was performed in 41 patients (59%) and abnormal glycoprotein expression was detected in 6 patients (15%). Of the 55 patients who had all tests performed, 22 patients (40%) had completely normal results. Of the routine tests, only PFA-CEPI or -CADP prolongation is associated with the likelihood of a PTEM abnormality (P<0.005). With the assistance of molecular testing, there were 2 cases of MYH-9 mutation-related platelet disorders, one of RUNX1 mutation-associated thrombocytopenia, one of York platelet syndrome, two of Bernard Soulier variants, one of Quebec syndrome and three of gray platelet syndrome or variants. Bleeding scores showed no statistically significant association with severity of any laboratory abnormalities. Conclusion In this cohort, the sensitivity of routine platelet testing in clinically suspected PDs is about 30-40%. Addition of platelet esoteric testing improves the sensitivity to 60%. However, the degree of platelet laboratory abnormalities do not predict severity of bleeding. The findings of this cohort underscore the importance of clinical assessment and both platelet routine and esoteric testing in investigation of patients with suspected PDs. Disclosures No relevant conflicts of interest to declare.

Abstract BACKGROUND: Complement-mediated thrombotic microangiopathies (TMAs) are a subset of TMAs in which the thrombocytopenia, microangiopathic hemolytic anemia, and end organ damage are caused by mutations in genes encoding the alternative complement pathway. Numerous complement genes have been implicated in complement-mediated TMAs including complement factor H (CFH), CD46 (MCP), complement factor I (CFI), complement component 3 (C3), complement factor B (CFB), factor H related 5 (CFHR5), and thrombomodulin (THBD) among others. Genetic analysis typically yields a mutation in 60% of patients whose TMA is presumed to be mediated by complement dysregulation. However, the description of novel disease-associated variants may increase this proportion. METHODS: A retrospective study of patients with TMAs diagnosed between 2000 and 2014 was performed. TMA diagnosis was made based on thrombocytopenia and evidence of microangiopathic hemolytic anemia. Analysis was performed with Alamut¨ software with additional in silico prediction tools (SIFT, MutationTaster, and Polyphen) for classification of gene variants. Variants of unknown significance (VUS) and likely pathogenic variants were further assessed using several mutation databases, including HGMD, ClinVar, and Factor H database RESULTS: Of patients diagnosed with a TMA, genetic analysis was performed in only a 10% of patients. Of the 29 patients with genetic studies performed, mutations were identified in 18 patients (62%). The majority of the mutations had been described previously in the literature, but four novel variants were identified: three missense and one splice-site. The table below summarizes these variants as well as laboratory findings on presentation. These were two variants of CFH, one variant of CFHR5, and one variant of CFI. In silico modeling of these variants revealed two polymorphisms likely to be pathogenic, one polymorphism likely benign given the lack of predicted splicing changes, and one VUS. Table 1. Protein Mutation Classification Age Sex Hemoglobin (g/dL) Platelets (thousands) Creatinine (mg/dL) CFH c.245-10_245-9dup Likely benign 61 F 11.6 51 6.7 CFH c.476G>A, p.Ser159Asn Likely pathogenic 43 F 9.1 101 9.1 CFHR5 c.1412G>A p.Gly471Glu Likely pathogenic 30 F 9.8 129 4.9 CFI c.1190T>A p.Val397Glu Unknown significance 51 M 9.4 125 6.1 DISCUSSION: With therapy available to target the alternative complement pathway, genetic analysis to identify genetic variants capable of causing complement mediated TMAs is an essential part of the evaluation. This genetic data must be interpreted and correlated with functional analysis and clinical phenotype. The reporting of novel variants in clinical databases, with inclusion of relevant clinical findings, is necessary to accurately classify and verify variants as pathologic mutations or benign polymorphisms. The full understanding of this diverse disease requires a more complete understanding of its genetics. While complement pathway-directed therapies are available, their rational use requires thorough interpretation of laboratory data, including genetic analysis. Disclosures Murray: Mayo Clinic: Patents & Royalties: Patent Application Filed.

Abstract Background Congenital/hereditary qualitative platelet disorders (CQPD) can be classified by platelet count (eg, normal or decreased) and platelet size as well as by functional defect. Based on mean platelet volume (MPV), congenital thrombocytopenias (CT) are classified as macro-thrombocytopenias (eg, Bernard-Soulier syndrome [BSS], MYH-9 [myosin heavy chain 9, non-muscle]-associated thrombocytopenias, gray platelet syndrome [GPS], etc.); microthrombocytopenias (eg, Wiskott-Aldrich syndrome and variants); and those with normal platelet size. CQPDs with normal platelet count include Glanzmann thrombasthenia (GT), dense granule storage pool disorders (DG-SPD) including Hermansky-Pudlak syndrome (HPS), platelet secretion disorders and many others. Diagnosis has relied on platelet counting and sizing, blood smear light microscopy, platelet aggregation (agg) and platelet function analyzer (PFA-100) studies. Platelet transmission electron microscopy (PTEM) and flow cytometry can provide supplementary information and molecular analysis is also evolving. The objective of this study was to determine the roles of platelet transmission electron microscopy (PTEM) and flow cytometry in the diagnosis of CQPD and CT. Methods In this retrospective cohort study, after IRB approval, the electronic medical record system was queried for patients (pt) with a confirmed CQPD or CT seen at Mayo Clinic between 2000 and 2015. A detailed chart review was undertaken. Results 54 pt (64% female) met our study criteria; median age was 32 years (range 1 day to 81 years). 18/54 (33%) pt had macrothrombocytopenia: BSS 4 (7%); MYH-9 10 (19%); gray platelet syndrome 4 (7%). 36/54 (66%) had normal MPV: Glanzmann thrombasthenia 6 (11%); storage pool disorders including DG-SPD 10 (19%) and HPS 2 (3%), mild alpha granule deficiency 3 (6%) and York platelet syndrome 4 (7%); platelet secretion disorders 4 (7%); ANKRD26 mutation 3 (6%); congenital amegakaryocytic thrombocytopenia 1 (2%); GATA-1 mutation 1 (2%); RUNX-1 mutation 1 (2%); and Jacobsen syndrome 1 (2%). 44 pt (81%) had a positive bleeding history: epistaxis 52%, cutaneous bleeding 57%, gastrointestinal bleeding 21% and menorrhagia 54%; 10 pt (19%) had a negative bleeding history. Results of standard and esoteric platelet testing are summarized in Table 1. Diagnosis in the 10 pt with glycoprotein deficiency (BSS or GT) was established by agg; flow cytometry was confirmatory but not necessary. Of the 23 pt with SPD, 5 had a negative bleeding history; 4 pt had normal agg and PFA-100 and were diagnosed exclusively by PTEM. In this group, the abnormalities on platelet aggregation and PFA were variable and PTEM allowed for a better definition of the specific abnormalities. For MYH-9 patients, PTEM confirmed leukocyte inclusions that had already been identified on light microscopy. PTEM was the only diagnostic modality able to identify the abnormality in York platelet syndrome. In 5/54 (9%) genetic testing was necessary for diagnosis (GATA-1, ANKRD26 and RUNX-1) Conclusion In this cohort, standard platelet assays established the diagnosis in the large majority of CQPD and CT. PTEM was essential for confirmation in DG-SPD, mild alpha granule deficiency and York platelet syndrome and useful in combination with molecular testing to establish a diagnosis in selected cases. Guidance on selection of patients for such specialized testing requires further study. Table 1. Results of standard and esoteric platelet testing for 54 patients with congenital qualitative platelet disorders and/or thrombocytopenia Disorder n (%) Platelet aggregation PFA PTEM Flow cytometry Confirmation by genetics Done Abnormal Done Abnormal Done Abnormal Done Abnormal Glanzmann thrombasthenia 6 (11) 6 6 5 5 1 0 3 3 0 Bernard-Soulier syndrome & variants 4 (7) 4 4 4 4 3 0 4 4 0 MYH-9 related disorders 10 (19) 7 2 8 3 5 5 4 2 5 Dense granule deficiency and HPS 12 (22) 12 8 12 8 12 12 4 0 0 Alpha granule deficiency* 7 (13) 7 4 7 6 7 7 4 4 1 York platelet syndrome 4 (7) 1 0 1 1 4 4 1 1 0 TXA2 or PG synthesis/receptor defect 4 (7) 4 4 4 3 3 0 3 0 0 CATM 1 (2) 0 - 0 - 0 - 0 - 1 ANKRD26 3 (6) 3 3 3 2 3 3 3 3 3 GATA-1 1 (2) 0 - 1 1 1 1 1 1 1 RUNX-1 1 (2) 1 0 1 1 0 - 0 - 1 Jacobsen syndrome 1 (2) 1 0 1 1 1 1 1 0 1 MYH-9: myosin heavy chain 9, non-muscle (MHY-9) associated thrombocytopenia, HPS: Hermansky-Pudlak Syndrome, TXA2: thromboxane A2, PG: prostaglandin CATM: congenital amegakaryocytic thrombocytopenia. * Includes gray platelet syndrome Disclosures Pardanani: Stemline: Research Funding.

Abstract Background: While Factor V Leiden is associated with an increased risk of thrombosis, the magnitude of that risk among homozygous carriers is uncertain. Methods: In a cross-sectional study of Mayo Clinic patients referred to the Special Coagulation Laboratory for a thrombophilia profile (n=379) over the 18-year period, 1996-2013, the prevalence of venous and arterial thrombosis was estimated for patients found to be Factor V Leiden carriers based on leukocyte genomic DNA genotyping. T tests and chi-square tests were used for continuous and categorical variables, respectively. Results: Among homozygous (n=111) and heterozygous (n=268) carriers, the mean age at testing (50.3 and 50.5 years, respectively; p=0.9) and the proportion of females (50% and 54%, respectively; p=0.5) did not differ significantly. Of 29 asymptomatic carriers at the time of testing, 14 were homozygotes. Of the remaining 350 carriers, the mean age at first venous or arterial thrombosis (42 vs 43.8 years; p=0.5) among homozygous and heterozygous carriers, respectively, did not differ significantly. Thirty-five (33%) and 83 (31%) homozygous and heterozygous carriers, respectively, had at least one recurrent venous or arterial thrombosis (p=0.72). The prevalence of deep venous thrombosis (DVT) was 61% and 46% in homozygous and heterozygous carriers, respectively (p=0.008); the prevalence of pulmonary embolism was 18% and 20%, respectively (p=0.69). The prevalence of arterial thrombosis (mainly stroke and/or TIA) was higher in heterozygous (23%) compared to homozygous carriers (8%). Conclusion: In the largest sample of homozygous Factor V Leiden carriers reported to date, thrombosis penetrance and phenotype did not appear to differ among homozygous vs. heterozygous carriers with the exception of a higher prevalence of DVT among homozygous carriers. These data should be interpreted with caution due to the potential for referral bias. Disclosures No relevant conflicts of interest to declare.