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The process of platelet production has so far been understood to be a 2-stage process: megakaryocyte maturation from hematopoietic stem cells followed by proplatelet formation, with each phase regulating the peripheral blood platelet count. Proplatelet formation releases into the bloodstream beads-on-a-string preplatelets, which undergo fission into mature platelets. For the first time, we show that preplatelet maturation is a third, tightly regulated, critical process akin to cytokinesis that regulates platelet count. We show that deficiency in cytokine receptor-like factor 3 (CRLF3) in mice leads to an isolated and sustained 25% to 48% reduction in the platelet count without any effect on other blood cell lineages. We show that Crlf3−/− preplatelets have increased microtubule stability, possibly because of increased microtubule glutamylation via the interaction of CRLF3 with key members of the Hippo pathway. Using a mouse model of JAK2 V617F essential thrombocythemia, we show that a lack of CRLF3 leads to long-term lineage-specific normalization of the platelet count. We thereby postulate that targeting CRLF3 has therapeutic potential for treatment of thrombocythemia.

AimsDetermination of the number of plasma cells in bone marrow biopsies is required for the diagnosis and ongoing evaluation of plasma cell neoplasms. We developed an automated digital enumeration platform to assess plasma cells identified by antigen expression in whole bone marrow sections in multiple myeloma, and compared it with manual assessments.MethodsBone marrow trephine biopsy specimens from 91 patients with multiple myeloma at diagnosis, remission and relapse were stained for CD138 and multiple myeloma oncogene 1 (MUM1). Manual assessment and digital quantification were performed for plasma cells in the entire trephine section. Concordance rates between manual and digital methods were evaluated for each antigen by intraclass correlation analyses (ICC) with associated Spearman’s correlations.ResultsThe digital platform counted 16 484–1 118 868 cells and the per cent CD138 and MUM1-positive plasma cells ranged from 0.05% to 93.5%. Overall concordance between digital and manual methods was 0.63 for CD138 and 0.89 for MUM1. Concordance was highest with diffuse plasma cell infiltrates (MUM1: ICC=0.90) and lowest when in microaggregates (CD138: ICC=0.13). Manual counts exceeded digital quantifications for both antigens (CD138: mean=26.4%; MUM1: mean=9.7%). Diagnostic or relapse threshold counts, as determined by CD138 manual assessments, were not reached with digital counting for 16 cases (18%).ConclusionsAutomated digital enumeration of the entire, immunohistochemically stained bone marrow biopsy section can accurately determine plasma cell burden, irrespective of pattern and extent of disease (as low as 0.05%). This increases precision over manual visual assessments which tend to overestimate plasma burden, especially for CD138, and when plasma cells are in clusters.

No specific translocation is associated with myeloproliferative neoplasms (MPNs). However, an interstitial deletion involving subband 17q11.2 which includes the NF1 gene, although rare, is a recurrent aberration in several myeloid disorders including MPNs. For the first time, we report an acquired novel translocation involving 10p13 and 17q11.2 in a 62-year-old Caucasian female which was referred for investigation of chronic and persistent unexplained thrombocytosis. The patient had no history of hematological sequelae and genomic testing for JAK2, CALR, and MPL mutations were negative. She was subsequently diagnosed with a triple negative essential thrombocythemia. Array-CGH analysis noted that the translocation harbored two cryptic deletions, one of which involved 17q11.2 encompassing the NF1 gene. One of the junction breakpoints involved the SUZ12 gene. Immunohistochemical assessment of the marrow trephine showed increased megakaryocytic expression of the SUZ12 protein, as well as EZH2 and Ki67; biochemical abnormalities suggestive of excess megakaryocytic hyperplasia. This novel translocation may affect the expression of SUZ12 and its downstream targets, and may represent a unique pathogenomic etiology which drives chronic thrombocytosis in essential thrombocythemia.

Simple Summary Approximately 50% of patients with uveal melanoma will develop incurable metastatic disease. This can be predicted, but requires a biopsy of the eye, which outside of centres of excellence, are not routinely performed. Given that uveal melanoma spreads through the blood, utilising circulating tumour cells from the blood might provide an alternative minimally invasive method to avoid the biopsy. However, the clinical application hinges on the detection rate of circulating tumour cells. Herein we assessed markers to improve the capture and detection of uveal melanoma circulating tumour cells and found that they could be detected in 86% of patients. We further found that ≥3 circulating tumour cells was significantly associated with worse survival. Abstract (1) Background: The stratification of uveal melanoma (UM) patients into prognostic groups is critical for patient management and for directing patients towards clinical trials. Current classification is based on clinicopathological and molecular features of the tumour. Analysis of circulating tumour cells (CTCs) has been proposed as a tool to avoid invasive biopsy of the primary tumour. However, the clinical utility of such liquid biopsy depends on the detection rate of CTCs. (2) Methods: The expression of melanoma, melanocyte, and stem cell markers was tested in a primary tissue microarray (TMA) and UM cell lines. Markers found to be highly expressed in primary UM were used to either immunomagnetically isolate or immunostain UM CTCs prior to treatment of the primary lesion. (3) Results: TMA and cell lines had heterogeneous expression of common melanoma, melanocyte, and stem cell markers. A multi-marker panel of immunomagnetic beads enabled isolation of CTCs in 37/43 (86%) patients with UM. Detection of three or more CTCs using the multi-marker panel, but not MCSP alone, was a significant predictor of shorter progression free (p = 0.040) and overall (p = 0.022) survival. (4) Conclusions: The multi-marker immunomagnetic isolation protocol enabled the detection of CTCs in most primary UM patients. Overall, our results suggest that a multi-marker approach could be a powerful tool for CTC separation for non-invasive prognostication of UM.

Background Acute myeloid leukaemia (AML) results from the clonal expansion of blast cells of myeloid origin driven by genomic defects. The advances in next-generation sequencing (NGS) have allowed the identification of many mutated genes important in the pathogenesis of AML. Aims In this study, we aimed to assess the mutation types and frequency in a Chinese cohort presenting with de novo AML cohort using a targeted NGS strategy. Methods In total, we studied samples from 87 adult patients with de novo AML who had no prior history of cytotoxic chemotherapy. Samples were evaluated using a 120-gene targeted NGS panel to assess the mutation profile. Results Of the 87 AML patients, there were 60 (69%) with a normal karyotype. 89.7% of patients had variants, with an average of 1.9 mutations per patient (range: 0-5 mutations per patient). DNMT3A variants were the most common, being detected in 33 patients (37.9%). NPM1 (34.5%), IDH1/2 (24.1%) and FLT3-ITD (20.7%) mutations was the next most common. Of the patients with DNMT3A mutations, 24.2% also had mutations NPM1 and FLT3-ITD and 6.1% NPM1, FLT3-ITD and IDH mutations. Conclusion Both DNMT3A and NPM1 mutations were more common than in other Chinese and Western AML cohorts that have been studied. DNMT3A mutations tended to co-occur with NPM1 and FLT3-ITD mutations and were most commonly seen with a normal karyotype.

Imaging flow cytometry is an automated method that enables cells and fluorescent signals to be visualized and quantified. Here, we describe a new imaging flow cytometry method whereby fluorescence in situ hybridization (FISH) is integrated with cell phenotyping. The method, called "immuno-flowFISH," provides an exciting new dimension for the analysis of genomic changes in cytological samples (e.g., blood, bone marrow). Cells are analyzed in suspension without any requirement for prior cell isolation or separation. Multiple antibodies and FISH probes, each with a unique fluorophore, can be added and many thousands of cells analyzed. Specific cell populations are identified by their antigenic profile and then analyzed for the presence of chromosomal defects. Immuno-flowFISH was applied to the assessment of chronic lymphocytic leukemia (CLL), a mature B-cell neoplasm where chromosomal abnormalities predict prognosis and treatment requirements. This integrated immunophenotyping and multi-probe FISH strategy could detect both structural and numerical chromosomal changes involving chromosomes 12 and 17 in CLL cells. Given that many thousands of cells were analyzed and the leukemic cells were positively identified by their immunophenotype, this multi-probe method adds precision to the cytogenomic analysis of CLL. © 2021 Wiley Periodicals LLC.

AimsCytogenetic abnormalities involving the IGH gene are seen in up to 55% of patients with multiple myeloma. Current testing is performed manually by fluorescence in situ hybridisation (FISH) on purified plasma cells. We aimed to assess whether an automated imaging flow cytometric method that uses immunophenotypic cell identification, and does not require cell isolation, can identify IGH abnormalities.MethodsAspirated bone marrow from 10 patients with multiple myeloma were studied. Plasma cells were identified by CD38 and CD138 coexpression and assessed with FISH probes for numerical or structural abnormalities of IGH. Thousands of cells were acquired on an imaging flow cytometer and numerical data and digital images were analysed.ResultsUp to 30 000 cells were acquired and IGH chromosomal abnormalities were detected in 5 of the 10 marrow samples. FISH signal patterns seen included fused IGH signals for IGH/FGFR3 and IGH/MYEOV, indicating t(4;14) and t(11;14), respectively. In addition, three IGH signals were identified, indicating trisomy 14 or translocation with an alternate chromosome. The lowest limit of detection of an IGH abnormality was in 0.05% of all cells.ConclusionsThis automated high-throughput immuno-flowFISH method was able to identify translocations and trisomy involving the IGH gene in plasma cells in multiple myeloma. Thousands of cells were analysed and without prior cell isolation. The inclusion of positive plasma cell identification based on immunophenotype led to a lowest detection level of 0.05% marrow cells. This imaging flow cytometric FISH method offers the prospect of increased precision of detection of critical genetic lesions involving IGH and other chromosomal defects in multiple myeloma.

Chromosomal analysis is traditionally performed by karyotyping on metaphase spreads, or by fluorescent in situ hybridization (FISH) on interphase cells or metaphase spreads. Flow cytometry was introduced as a new method to analyze chromosomes number (ploidy) and structure (telomere length) in the 1970s with data interpretation largely based on fluorescence intensity. This technology has had little uptake for human cytogenetic applications primarily due to analytical challenges. The introduction of imaging flow cytometry, with the addition of digital images to standard multi-parametric flow cytometry quantitative tools, has added a new dimension. The ability to visualize the chromosomes and FISH signals overcomes the inherent difficulties when the data is restricted to fluorescence intensity. This field is now moving forward with methods being developed to assess chromosome number and structure in whole cells (normal and malignant) in suspension. A recent advance has been the inclusion of immunophenotyping such that antigen expression can be used to identify specific cells of interest for specific chromosomes and their abnormalities. This capability has been illustrated in blood cancers, such as chronic lymphocytic leukemia and plasma cell myeloma. The high sensitivity and specificity achievable highlights the potential imaging flow cytometry has for cytogenomic applications (i.e., diagnosis and disease monitoring). This review introduces and describes the development, current status, and applications of imaging flow cytometry for chromosomal analysis of human chromosomes.

Myeloproliferative neoplasms are characterised by somatic mutations in pathways that regulate cell proliferation, epigenetic modifications, RNA splicing or DNA repair. Assessment of the mutational profile assists diagnosis and classification, but also aids assessment of prognosis, and may guide the use of emerging targeted therapies. The most practical way to provide information on numerous genetic variants is by using massively parallel sequencing, commonly in the form of disease specific next generation sequencing (NGS) panels. This review summarises the diagnostic and prognostic value of somatic mutation testing in Philadelphia-negative myeloproliferative neoplasms: polycythaemia vera, essential thrombocythaemia, primary myelofibrosis, chronic neutrophilic leukaemia, systemic mastocytosis, and chronic eosinophilic leukaemia. NGS panel testing is increasing in routine practice and promises to improve the accuracy and efficiency of pathological diagnosis and prognosis. Refereed/Peer-reviewed

In 2012, the International Council for Standardization in Hematology (ICSH) published recommendations for the identification, quantitation, and diagnostic value of schistocytes. In the present review, the impact of these recommendations is evaluated. This work is based on citations in peer-reviewed papers published since 2012. The first 2012 ICSH Recommendations have also been revised to incorporate newly published data in the literature and current best laboratory practice. Recommended reference ranges have been proposed for healthy adults and full-term neonates of 1% or less schistocytes. More than 1% of morphologically identified schistocytes on the blood film are considered suspicious for thrombotic microangiopathy. For preterm infants, a normal level of 5% or less is recommended. The fragment red cell count (FRC) generated by some automated hematological analyzers provides a valuable screening tool for the presence of schistocytes. Specifically, the absence of FRCs can be used as a valuable parameter to exclude the presence of schistocytes on the blood film. The validity and usefulness of microscope schistocytes and automated FRCs, respectively, are discussed in the context of the laboratory diagnostic tests used for thrombotic microangiopathies.

Supplemental Digital Content is available in the text., Background: Approximately 25% of patients with pulmonary arterial hypertension (PAH) have been found to harbor rare mutations in disease-causing genes. To identify missing heritability in PAH, we integrated deep phenotyping with whole-genome sequencing data using Bayesian statistics. Methods: We analyzed 13 037 participants enrolled in the NBR study (NIHR BioResource—Rare Diseases), of which 1148 were recruited to the PAH domain. To test for genetic associations between genes and selected phenotypes of pulmonary hypertension, we used the Bayesian rare variant association method BeviMed. Results: Heterozygous, high impact, likely loss-of-function variants in the kinase insert domain receptor (KDR) gene were strongly associated with significantly reduced transfer coefficient for carbon monoxide (posterior probability=0.989) and older age at diagnosis (posterior probability=0.912). We also provide evidence for familial segregation of a rare nonsense KDR variant with these phenotypes. On computed tomographic imaging of the lungs, a range of parenchymal abnormalities were observed in the 5 patients harboring these predicted deleterious variants in KDR. Four additional PAH cases with rare likely loss-of-function variants in KDR were independently identified in the US PAH Biobank cohort with similar phenotypic characteristics. Conclusions: The Bayesian inference approach allowed us to independently validate KDR, which encodes for the VEGFR2 (vascular endothelial growth factor receptor 2), as a novel PAH candidate gene. Furthermore, this approach specifically associated high impact likely loss-of-function variants in the genetically constrained gene with distinct phenotypes. These findings provide evidence for KDR being a clinically actionable PAH gene and further support the central role of the vascular endothelium in the pathobiology of PAH.

No specific translocation is associated with myeloproliferative neoplasms (MPNs). However, an interstitial deletion involving subband 17q11.2 which includes the NF1 gene, although rare, is a recurrent aberration in several myeloid disorders including MPNs. For the first time, we report an acquired novel translocation involving 10p13 and 17q11.2 in a 62-year-old Caucasian female which was referred for investigation of chronic and persistent unexplained thrombocytosis. The patient had no history of hematological sequelae and genomic testing for JAK2, CALR, and MPL mutations were negative. She was subsequently diagnosed with a triple negative essential thrombocythemia. Array-CGH analysis noted that the translocation harbored two cryptic deletions, one of which involved 17q11.2 encompassing the NF1 gene. One of the junction breakpoints involved the SUZ12 gene. Immunohistochemical assessment of the marrow trephine showed increased megakaryocytic expression of the SUZ12 protein, as well as EZH2 and Ki67; biochemical abnormalities suggestive of excess megakaryocytic hyperplasia. This novel translocation may affect the expression of SUZ12 and its downstream targets, and may represent a unique pathogenomic etiology which drives chronic thrombocytosis in essential thrombocythemia.

Gray platelet syndrome (GPS) is a rare recessive disorder caused by variants in NBEAL2 and characterized by bleeding symptoms, the absence of platelet ɑ-granules, splenomegaly and bone marrow (BM) fibrosis. Due to its rarity, it has been difficult to fully understand the pathogenic processes that lead to these clinical sequelae. To discern the spectrum of pathological features, we performed a detailed clinical genotypic and phenotypic study of 47 GPS patients. We identified 33 new causal variants in NBEAL2. Our GPS patient cohort exhibited known phenotypes, including macro-thrombocytopenia, BM fibrosis, megakaryocyte emperipolesis of neutrophils, splenomegaly, and elevated serum vitamin B12 levels. We also observed novel clinical phenotypes; these include reduced leukocyte counts and increased presence of autoimmune disease and positive autoantibodies. There were widespread differences in the transcriptome and proteome of GPS platelets, neutrophils, monocytes, and CD4-lymphocytes. Proteins less abundant in these cells were enriched for constituents of granules, supporting a role for Nbeal2 in the function of these organelles across a wide range of blood cells. Proteomic analysis of GPS plasma showed increased levels of proteins associated with inflammation and immune response. One quarter of plasma proteins increased in GPS are known to be synthesized outside of hematopoietic cells, predominantly in the liver. In summary, our data demonstrate that, in addition to the well-described platelet defects in GPS, there are also immune defects. The abnormal immune cells may be the drivers of systemic abnormalities, such as autoimmune disease.

The diagnosis of haematological malignancies requires an understanding of the diseases and the uses and limitations of the range of available investigations. The relative importance of different investigations varies by disease entity. The blood count is one of the most widely used tests in all of medicine and often the first indication of an underlying haematological malignancy. Some blood count features are ‘diagnostic’ and others may give an indication of a bone marrow defect. Morphological assessment of a stained blood film adds value to an abnormal blood count. It may identify abnormal morphology of red cells, leucocytes, or platelets which may be specific and diagnostic, or give clues suggesting a diagnosis. Bone marrow aspirate (liquid sample) gives cytological detail, and trephine biopsy provides information about marrow cellularity, architecture, cellular distribution, and extent of fibrosis. Immunophenotyping detects cellular antigens in clinical samples and is essential in the diagnosis and classification of haematological malignancies. It is also used for disease staging and monitoring, to detect surrogate markers of genetic aberrations, identify potential immunotherapeutic targets, and to aid prognostic prediction. Cytogenetics assesses the number and structure of whole chromosomes and chromosomal regions in neoplastic cells and is performed to diagnose and classify some haematological malignancies. Molecular genetic methods facilitate the detection of mutations, rearrangements, or translocations in genes. Applications in malignant haematology include confirming clonality, detecting disease-associated genotypes, determining prognosis, disease monitoring following therapy, predicting imminent clinical relapse, and identifying patients who are likely (or not) to respond to new targeted inhibitor therapies.

Gray platelet syndrome (GPS) is a rare recessive disorder caused by biallelic variants in NBEAL2 and characterized by bleeding symptoms, the absence of platelet α-granules, splenomegaly, and bone marrow (BM) fibrosis. Due to the rarity of GPS, it has been difficult to fully understand the pathogenic processes that lead to these clinical sequelae. To discern the spectrum of pathologic features, we performed a detailed clinical genotypic and phenotypic study of 47 patients with GPS and identified 32 new etiologic variants in NBEAL2. The GPS patient cohort exhibited known phenotypes, including macrothrombocytopenia, BM fibrosis, megakaryocyte emperipolesis of neutrophils, splenomegaly, and elevated serum vitamin B12 levels. Novel clinical phenotypes were also observed, including reduced leukocyte counts and increased presence of autoimmune disease and positive autoantibodies. There were widespread differences in the transcriptome and proteome of GPS platelets, neutrophils, monocytes, and CD4 lymphocytes. Proteins less abundant in these cells were enriched for constituents of granules, supporting a role for Nbeal2 in the function of these organelles across a wide range of blood cells. Proteomic analysis of GPS plasma showed increased levels of proteins associated with inflammation and immune response. One-quarter of plasma proteins increased in GPS are known to be synthesized outside of hematopoietic cells, predominantly in the liver. In summary, our data show that, in addition to the well-described platelet defects in GPS, there are immune defects. The abnormal immune cells may be the drivers of systemic abnormalities such as autoimmune disease. ispartof: BLOOD vol:136 issue:17 pages:1956-1967 ispartof: location:United States status: published

The heritable thrombocytopenias (HTs) are genetically heterogeneous rare disorders in whichreduced circulating platelet levels may be associated with nonhematological features. Amongrecently discovered HTs, DIAPH1-related disorder (D-RD; OMIM #124900) was initially reported in pedigrees with macrothrombocytopenia and hearing loss. This phenotype segregated with aheterozygous p.R1213* variant in DIAPH1, which encodes the cytoskeletal regulator diaphanoushomolog 1 (DIAPH1). This predicted truncation of the DIAPH1 C terminus diaphanous autoregulatory domain (DAD) and was proposed to confer gain-of-function, resulting in megakaryocyte (MK) cytoskeletal dysregulation and impaired proplatelet formation. Macrothrombocytopenia and hearing loss have subsequently been reported in further isolated pedigrees with DAD DIAPH1 variants,4-6 suggesting that D-RD is a distinct syndromic HT. However, other descriptions of similar DIAPH1 variants include hearing loss but not hematological findings. To provide a full phenotypic description of D-RD and the relationship with different DIAPH1 variants, we report detailed hematological findings from 5 D-RD pedigrees, including the in vitro response and clinical outcome of treatment with the thrombopoietin (TPO) receptor agonisteltrombopag.

Background Both anaemia and red blood cell (RBC) transfusion are common and associated with adverse outcomes in patients admitted to the intensive care unit (ICU). The aim of this study was to determine whether serum hepcidin concentration, measured early after ICU admission in patients with anaemia, could identify a group in whom intravenous (IV) iron therapy decreased the subsequent RBC transfusion requirement. Methods We conducted a prospective observational study nested within a multicenter randomized controlled trial (RCT) of IV iron versus placebo. The study was conducted in the ICUs of four tertiary hospitals in Perth, Western Australia. Critically ill patients with haemoglobin (Hb) of

Chronic Lymphocytic Leukaemia (CLL), the most common leukaemia in the Western world, has a characteristic phenotype and prognosis largely defined by the presence of cytogenetic aberrations. The gold standard for detecting these cytogenetic abnormalities is interphase fluorescence in situ hybridisation (FISH) performed on cell smears or tissue sections on glass slides. Fluorescently labelled DNA probes bind to specific chromosomal regions and the signal detected by fluorescent microscopy. Generally only 200 cells are assessed and the limit of sensitivity is 3% positive cells. Here we report the development and use of imaging flow cytometry to assess chromosomes by FISH in phenotyped CLL cells in suspension. Thousands of CLL cells, identified by their phenotype, are assessed for specific FISH probe signals using an automated, high throughput imaging flow cytometer. The "extended depth of field" capability of the imaging flow cytometer enables FISH probe signals ("spots") to be resolved and localised within the (stained) nucleus of the immunophenotyped cells. We report the development of the automated "immuno-flowFISH" on normal blood using the Amnis ImageStreamX mark II platform and illustrate the clinical application of the method for the assessment of chromosome 12 in CLL. It is a powerful new method which has potential to be applied at diagnosis for disease stratification, and following treatment to assess residual disease. These applications will assist clinicians in optimising therapeutic decision making and thereby improve patient outcome.

Chronic lymphocytic leukaemia is a genetically heterogeneous disease with treatment and prognosis varying based on chromosomal abnormalities. These are detectable in up to 80% of cases when tested on the nuclei of interphase cells by fluorescence in situ hybridisation (FISH). Despite the clinical importance of FISH in management, as only up to 200 nuclei are generally assessed, it is not suitable for minimal residual disease (MRD) assessment. Since clinical decisions are based on detection thresholds of 10 -4, MRD assays are restricted to flow cytometry and molecular based assessment. Here we have explored the utility of a cutting-edge automated imaging flow cytometry method that incorporates cell immunophenotype and FISH ("immuno-flowFISH") to detect chromosomal abnormalities in CLL. Aims: Our aim was to determine the capability of immuno-flowFISH using imaging flow cytometry to detect del(17p) and +12 in CLL, and, the lowest limit of detection. We hypothesized that this integrated automated immuno-flowFISH method would be suitable for MRD assessment of CLL. Methods: Blood from 75 patients with CLL, at diagnosis or on therapy, was analysed. For MRD studies, cells from the CI cell line were spiked into normal blood at concentrations of 0.001 - 10%. After red cell lysis, samples were incubated with CD3, CD5 and CD19 fluorophore-conjugated antibodies (fluorophores: BV480, BV605, AF647). Following fixation and membrane permeabilization, DNA was denatured at 78 oC for 5 mins. FISH probes to 17p12 and centromeres of chromosomes 12 and 17 were added and hybridized for 24 hours at 42 oC. Nuclei were then stained with SYTOX AADvanced and up to 600,000 cells acquired on the Amnis ® ImageStream ®XMk II imaging flow cytometer. Digital images (x60 objective) and quantitative data derived from computational algorithms (IDEAS software) were used to assess FISH signals overlying cell nuclei. IDEAS was then used to assess the number and percent CD19/CD5-positive CLL cells with FISH abnormalities. Results: Between 10,000 and 600,000 cells (mean 60,000) were acquired. CLL (CD19/CD5-positive) and T- (CD3/CD5-positive) cells could be clearly identified by their immunophenotype and assessed individually for probe signals. FISH signals were identifiable on the digital images as specific "spots" overlying the SYTOX AADvanced nuclear stain. The IDEAS software could enumerate the number of FISH spots per cell and this was confirmed by quantitative mean channel fluorescence intensity for each probe. A chromosome 12 or 17 abnormality was detected in 23 of the 75 CLL cases. Of these, 10 cases had only one 17p signal (but 2 for the centromere of chromosome 17), indicative of del(17p). Del(17p) was detected in 2-35% of CD19/CD5-positive cells (i.e. 0.4-23% or 270-35,441 of all cells), the lowest seen in a patient on cytoreductive therapy. In 13/75 cases, there were 3 FISH signals for CEP12, consistent with trisomy 12 (+12) in 0.1-46% of all cells analysed; the lowest number of 0.1% was when 26 out of 26,000 cells analysed were CD19/CD5-positive and had +12. We also performed multi-FISH, incorporating CEP12, CEP17 and 17p probes together with the CD3, CD5 and CD19 antibodies. This required 7-fluorophores (antibodies, probes and nucleus) and confirmed the ability to detect del(17p) and chromosome 12 copy number simultaneously in a single analysis. Spiking of CI CLL cells into normal blood demonstrated that +12 could be detected to a lowest limit of 10 -5. In all analyses, CLL cells had normal diploid spots for the control CEP17 probe, and the CD3/CD5-positive T cells had dual signals for CEP12, CEP17 and 17p12 probes on numerical analysis and on digital imagery. Conclusion: This study of confirms that high-throughput automated imaging flow cytometry, integrating FISH and immunophenotyping, can detect chromosomal defects in CLL. The lowest limit of detection for a FISH-detectable abnormality was 10 -5. This high sensitivity and specificity exceeds current clinical practice (10 -4), and was achieved through the analysis of many thousands of cells and positive identification of CLL cells based on their phenotype. This immuno-flowFISH method does not require any prior cell separation and is automated. It adds a new dimension to chromosomal analysis in CLL, both at diagnosis and for MRD monitoring. The high precision and specificity of immuno-flowFISH illustrates that this has a real place as a new MRD assessment tool for CLL. Disclosures No relevant conflicts of interest to declare.

Myeloproliferative neoplasms (MPN) are a group of clonal hematopoietic stem cell disorders characterized by well-known driver mutations [1]. The mutational status of Janus kinase 2 (JAK2), calretic...

Introduction The bacterial content of donated human milk is either endogenous or introduced via contamination. Defining milk bank bacterial content will allow researchers to devise appropriate tests for significant and commonly encountered organisms. Objective A retrospective audit was conducted on data recorded from the Perron Rotary Express Milk Bank, King Edward Memorial Hospital, Subiaco, Western Australia. This aimed to describe the incidence of bacterial species detected in donated human milk and to identify potentially pathogenic bacteria. Material and methods The data comprised of 2890 batches donated by 448 women between 2007 and 2011. Results Coagulase negative Staphylococcus (CoNS) represented the highest prevalence of bacteria in donated milk, isolated from 85.5% of batches (range: 20 to 650,000CFU/mL) followed by Acinetobacter species in 8.1% of batches (range: 100 to 180,000CFU/mL). Staphylococcus aureus was the most prevalent potentially pathogenic bacteria in 5% of batches (range: 40 to 100,000CFU/mL). Conclusion Further investigation is warranted to better define the risks posed by the presence of toxin-producing S. aureus in raw and pasteurized human milk which may allow minimization of risk to the preterm infants.

Mutations in more than 250 genes are implicated in inherited retinal dystrophy; the encoded proteins are involved in a broad spectrum of pathways. The presence of unsolved families after highly parallel sequencing strategies suggests that further genes remain to be identified. Whole-exome and -genome sequencing studies employed here in large cohorts of affected individuals revealed biallelic mutations in ARHGEF18 in three such individuals. ARHGEF18 encodes ARHGEF18, a guanine nucleotide exchange factor that activates RHOA, a small GTPase protein that is a key component of tight junctions and adherens junctions. This biological pathway is known to be important for retinal development and function, as mutation of CRB1, encoding another component, causes retinal dystrophy. The retinal structure in individuals with ARHGEF18 mutations resembled that seen in subjects with CRB1 mutations. Five mutations were found on six alleles in the three individuals: c.808A>G (p.Thr270Ala), c.1617+5G>A (p.Asp540Glyfs ∗ 63), c.1996C>T (p.Arg666 ∗ ), c.2632G>T (p.Glu878 ∗ ), and c.2738_2761del (p.Arg913_Glu920del). Functional tests suggest that each disease genotype might retain some ARHGEF18 activity, such that the phenotype described here is not the consequence of nullizygosity. In particular, the p.Thr270Ala missense variant affects a highly conserved residue in the DBL homology domain, which is required for the interaction and activation of RHOA. Previously, knock-out of Arhgef18 in the medaka fish has been shown to cause larval lethality which is preceded by retinal defects that resemble those seen in zebrafish Crumbs complex knock-outs. The findings described here emphasize the peculiar sensitivity of the retina to perturbations of this pathway, which is highlighted as a target for potential therapeutic strategies.

Inherited retinal disease is a common cause of visual impairment and represents a highly heterogeneous group of conditions. Here, we present findings from a cohort of 722 individuals with inherited retinal disease, who have had whole-genome sequencing (n = 605), whole-exome sequencing (n = 72), or both (n = 45) performed, as part of the NIHR-BioResource Rare Diseases research study. We identified pathogenic variants (single-nucleotide variants, indels, or structural variants) for 404/722 (56%) individuals. Whole-genome sequencing gives unprecedented power to detect three categories of pathogenic variants in particular: structural variants, variants in GC-rich regions, which have significantly improved coverage compared to whole-exome sequencing, and variants in non-coding regulatory regions. In addition to previously reported pathogenic regulatory variants, we have identified a previously unreported pathogenic intronic variant in $\textit{CHM}$ in two males with choroideremia. We have also identified 19 genes not previously known to be associated with inherited retinal disease, which harbor biallelic predicted protein-truncating variants in unsolved cases. Whole-genome sequencing is an increasingly important comprehensive method with which to investigate the genetic causes of inherited retinal disease.

Platelets are subcellular blood elements with a well-established role in haemostasis. Upon activation platelets undergo granule exocytosis, resulting in α-granule P-Selectin being expressed on the cell membrane. This allows binding of activated platelets to P-Selectin glycoprotein ligand 1 (PSGL-1) expressing leukocytes, forming leukocyte-platelet aggregates (LPAs). Whole blood flow cytometry (FCM) has demonstrated that elevated circulating LPAs (especially monocyte LPAs) are linked to atherothrombosis in high risk patients, and that activated platelet binding influences monocytes towards a pro-adhesive and pro-atherogenic phenotype. However, a limitation of conventional FCM is the potential for coincident events to resemble LPAs despite no tethering. Imaging cytometry can be used to characterize LPA formation and distinguish circulating MPAs from coincidental events. Platelets and leukocyte subsets are identified by expression of surface markers (e.g. the lipopolysachharide receptor CD14 on monocytes, glycoprotein Ib CD42b on platelets). In conventional FCM, all events with both leukocyte and platelet characteristics are designated as LPAs. However, by using an 'internal' mask based on the brightfield image and the fluorescent platelet identifier, imaging flow cytometry is able to distinguish leukocytes with tethered platelets (genuine LPAs) from leukocyte with coincidental, untethered platelets nearby. Mechanisms (e.g. adhesion molecules) or consequences (e.g. signal transduction) can then be separately analysed in platelet tethered and untethered leukocytes. Imaging flow cytometry therefore provides a more accurate approach for both enumeration and analysis of LPAs than conventional FCM.

Del(17p) in chronic lymphocytic leukemia (CLL) and plasma cell myeloma has a unique genomic profile leading to refractoriness to conventional therapies and poor overall survival. Detection is generally by fluorescence in situ hybridization (FISH) on a slide with analysis of up to 200 nuclei, not necessarily all of being neoplastic cells. The small cell sample analyzed, and high threshold for a positive result (>5% positive cells) makes FISH a low precision test. This means false negative results are inevitable, especially if del(17p) is only in a minor clone, potentially leading to suboptimal treatment. To address this, we developed an automated FISH method with analysis on an imaging flow cytometer, an instrument with the functionality of a standard flow cytometer which generates high-resolution digital images of each cell. By combining immunophenotyping with FISH, on whole cells in a single test, we can detect chromosomal defects in cells with a specific phenotype. Aims: Our aim was to determine the capability of this automated integrated immunophenotyping-FISH imaging flow cytometry method to detect del(17p) in CLL and myeloma, the two commonest hematological malignancies, and in which this genetic defect encodes poor prognosis. We hypothesized that it would be more sensitive and specific than standard FISH. Methods: Bone marrow and/or blood samples in EDTA anticoagulant from 19 cases of CLL or myeloma, at diagnosis or on therapy, were studied. After red cell lysis, cells were incubated with fluorochrome-conjugated antibodies to CD3, CD5, CD19, CD38, and CD138 antigens (fluorochromes: BV480, BV605, AF647). Following fixation, cell membranes were permeabilized and double-stranded DNA denatured (78oC for 5 mins). FISH probes to the centromere of chromosome 17 (CEP17, Spectrum Green) and 17p12 locus (Orange-Red) were added and hybridized for 24 hours at 37oC. Nuclei were stained with SYTOX AADvanced. Data for up to 200,000 cells was collected on the Amnis® ImageStream®XMk II imaging flow cytometer. Digital images (x60) and quantitative data derived from computational algorithms (IDEAS software) were used to assess FISH signals overlying the nuclei of CD5/CD19-positive CLL cells or CD38/CD138-positive plasma cells for each probe. Digital images and quantitative data were assessed for FISH signals within immunophenotyped cells. Results: Between 10,000 and 200,000 (mean 60,000) cells were analyzed per sample. The FISH signals were seen on the digital images and confirmed by quantitative mean channel fluorescence intensity of the probes. There were 12 CLL cases with one 17p FISH signal in the CD5/CD19-positive population, with the number of del(17p) CLL cells ranging from 2 - 35% (or 0.4 - 23% of all cells analyzed) (Fig 1). This amounted to between 270 and 35,441 cells in the analysed sample with del(17p). The lowest del(17p) burden was in a patient on cytoreductive therapy. All CLL cells had normal diploid spots for the control CEP17 probe, and the CD3/CD5-positive T cells had dual signals for both CEP17 and 17p12 probes. There were 5 myeloma cases with 1 FISH signal for 17p overlying the nucleus of the CD38/CD138-positive plasma cells (Fig 2). In these cases, 52-90% of cells (15,600-18,000 cells) had a plasma cell phenotype and 13-19% of these (or 2,340-2,964 CD38/CD138-positive cells) showed del(17p). This represented 1-5% of all cells in the sample. All gated plasma cells had 2 FISH spots for CEP17. Conclusion: This imaging flow cytometry method that integrates FISH with immunophenotyping could detect del(17p) in CLL and myeloma with a lowest limit of detection of 0.4% and 1% respectively. The high sensitivity was achieved as many thousands of cells were analyzed, and 17p was only assessed in gated cells with the phenotype of interest (i.e. CD5/CD19 or CD38/CD138). This method, that includes positive cell identification by phenotype, precludes the need for prior cell sorting or purification. Imaging flow cytometry for del(17p) by "immuno-flowFISH" brings a new dimension to FISH analysis at diagnosis and for disease monitoring. Its high precision and specificity will enable detection of del(17p), even when only present in minor sub-clones, for therapeutic decision making and prognostic stratification. This technique has a real place in clinical assessment of del(17p) in CLL and myeloma and could be applied for other significant chromosomal defects of therapeutic and prognostic significance. Figure 1 Disclosures Augustson: Roche: Other: Support of parent study and funding of editorial support. Cheah:Celgene, F. Hoffmann-La Roche, Abbvie, MSD: Research Funding; Celgene, F. Hoffmann-La Roche, MSD, Janssen, Gilead, Ascentage Pharma, Acerta, Loxo Oncology, TG therapeutics: Honoraria.

Imaging flow cytometry is emerging as a diagnostic tool for the assessment of leukemia. It has the functionality of standard flow cytometry and generates high-resolution digital images of each cell with quantifiable numerical data. We demonstrate the use of an automated high-throughput method for performing fluorescence in situ hybridization (FISH) on immunophenotyped whole cells in suspension and analyzed by imaging flow cytometry, a technique called "Immuno-flowFISH". The aim of this study was to demonstrate the application of immuno-flowFISH for the detection of chromosomal abnormalities in CLL, specifically trisomy 12 and del(17p). Mononuclear cells were isolated and immunophenotyped with fluorescently conjugated CD3, CD5, and CD19 monoclonal antibodies. Following fixation, cells were permeabilized, dsDNA denatured and hybridized with chromosome 12 or 17 enumeration (CEP 12 and CEP17) and 17p12 locus-specific FISH probes. Cells were analyzed on the Amnis ImageStream®X Mark II to assess the number and percent FISH-positive CLL cells and the ratio of FISH spot counts for CD5/CD19-positive CLL cells to CD3/CD5-positive T cells (FISH "mean spot ratio"). Deletion of 17p was detected in about 8% of cases to date, with del(17p) ranged from 3.5-22.8% and the FISH "mean spot ratio" 0.86-0.96. Immuno-flowFISH also detected a minimal residual disease case with +12 with a limit of detection of 0.13% and a rare case that presented with atypical phenotype and cytogenetics. Immuno-flowFISH could detect del(17p) in phenotypically identified CD5/CD19-positive B-cells. The 100-fold increase in analyzed cells, as well as the addition of cell phenotype increased the sensitivity and specificity over current clinical FISH testing. Furthermore, immuno-flowFISH analysis demonstrated specific utility in unique clinical scenarios such as residual disease and atypical biology cases which may be of significant benefit with regards to prognostication and MRD analysis. The method will assist in therapeutic decision making and disease monitoring for many hematological malignancies. © 2019 International Society for Advancement of Cytometry.

There is increasing recognition of circulating tumour DNA (ctDNA) as a non-invasive alternative to tumour tissue for the molecular characterisation and monitoring of disease. Recent evidence suggests that cancer-associated changes can also be detected in the DNA contained within extracellular vesicles (EVs). As yet, there has been limited investigation into the relationship between EV DNA and ctDNA, and no studies have examined the EV DNA of breast cancer patients. The aim of this study was to use low-pass whole-genome sequencing to identify copy number variants (CNVs) in serial samples of both ctDNA and EV DNA from a patient with breast cancer. Of the 52 CNVs identified in tumour DNA, 36 (69%) were detected in at least one ctDNA sample and 13 (25%) in at least one EV DNA sample. The number of detectable variants in ctDNA and EV DNA increased over the natural history of the patient&rsquo, s disease, which was associated with progression to cerebral metastases. This case study demonstrates that, while CNVs are detectable in patient EV DNA, ctDNA has greater sensitivity than EV DNA for serial monitoring of breast cancer.

Advances in science education research have the potential to improve the way students learn to perform scientific interpretations and understand science concepts. We developed active, collaborative activities to teach skills in manipulating flow cytometry data using FlowJo software. Undergraduate students were given compensated clinical flow cytometry listmode output (FCS) files and asked to design a gating strategy to diagnose patients with different hematological malignancies on the basis of their immunophenotype. A separate cohort of research trainees was given uncompensated data files on which they performed their own compensation, calculated the antibody staining index, designed a sequential gating strategy, and quantified rare immune cell subsets. Student engagement, confidence, and perceptions of flow cytometry were assessed using a survey. Competency against the learning outcomes was assessed by asking students to undertake tasks that required understanding of flow cytometry dot plot data and gating sequences. The active, collaborative approach allowed students to achieve learning outcomes not previously possible with traditional teaching formats, for example, having students design their own gating strategy, without forgoing essential outcomes such as the interpretation of dot plots. In undergraduate students, favorable perceptions of flow cytometry as a field and as a potential career choice were correlated with student confidence but not the ability to perform flow cytometry data analysis. We demonstrate that this new pedagogical approach to teaching flow cytometry is beneficial for student understanding and interpretation of complex concepts. It should be considered as a useful new method for incorporating complex data analysis tasks such as flow cytometry into curricula.

Fluorescence in situ hybridization (FISH) is a microscopy technique which uses a fluorescent probe to detect DNA sequences and is generally performed on metaphase spreads or interphase nuclei of intact cells on a slide. In a diagnostic laboratory, cells are hybridized with fluorescent probes and up to 200 cells counted for the number of cells with probe "spots." Recent modifications to standard FISH include immuno-FISH, where chromosomal abnormalities are detected only in cells by their phenotype, and S-FISH where probe hybridization is performed on whole cells in suspension. Here we describe the development of an immuno-S-FISH method that combines immunophenotyping and FISH analysis of cells in suspension followed by analysis on an imaging flow cytometer. This single platform technique couples microscopy with flow cytometry and "spot" detection of bound FISH probe. Automated immuno-S-FISH enables large numbers of analyzed cells to be identified by phenotype and assessed for specific chromosomal determinants by FISH. This novel robust method enables quantitative cell population analysis and "spot" counting for large numbers of cells. We report method optimization of this imaging immuno-S-FISH flow cytometry protocol which has capability for many clinical applications. © 2016 International Society for Advancement of Cytometry.

Aims Megakaryocyte expansion in myeloproliferative neoplasms (MPNs) is due to uncontrolled proliferation accompanied by dysregulation of proapoptotic and antiapoptotic mechanisms. Here we have investigated the intrinsic and extrinsic apoptotic pathways of megakaryocytes in human MPNs to further define the mechanisms involved. Methods The megakaryocytic expression of proapoptotic caspase-8, caspase-9, Diablo, p53 and antiapoptotic survivin proteins was investigated in bone marrow specimens of the MPNs (n=145) and controls (n=15) using immunohistochemistry. The megakaryocyte percentage positivity was assessed by light microscopy and correlated with the MPN entity, JAK2 V617F / CALR mutation status and platelet count. Results The proportion of megakaryocytes in the MPNs expressing caspase-8, caspase-9, Diablo, survivin and p53 was significantly greater than controls. A greater proportion of myeloproliferative megakaryocytes expressed survivin relative to its reciprocal inhibitor, Diablo. Differences were seen between myelofibrosis, polycythaemia vera and essential thrombocythaemia for caspase-9 and p53. CALR -mutated cases had greater megakaryocyte p53 positivity compared to those with the JAK2 V617F mutation. Proapoptotic caspase-9 expression showed a positive correlation with platelet count, which was most marked in myelofibrosis and CALR -mutated cases. Conclusions Disruptions targeting the intrinsic apoptotic cascade promote megakaryocyte hyperplasia and thrombocytosis in the MPNs. There is progressive dysfunction of apoptosis as evidenced by the marked reduction in proapoptotic caspase-9 and accumulation of p53 in myelofibrosis. The dysfunction of caspase-9, which is necessary for proplatelet formation, may be the mechanism for the excess thrombocytosis associated with CALR mutations. Survivin seems to be the key protein mediating the megakaryocyte survival signature in the MPNs and is a potential therapeutic target.

BackgroundTransforming growth factor α (TGFα) is a peptide growth factor known to be expressed in normal haemopoiesis. It is also expressed in a range of epithelial neoplasms but has not been assessed in haemopoietic malignancies. We have performed an immunohistochemical evaluation of TGFα in acute and chronic myeloid malignancies.MethodsTGFα expression was semiquantitatively assessed in 69 normal bone marrow trephines and 157 cases of myeloid malignancy using an immunohistochemical approach.ResultsBlast cells of myeloid origin in acute myeloid leukaemia (AML), myelodysplasia and accelerated and blast phases of chronic myeloid leukaemia (CML) were TGFα positive. In acute promyelocytic leukaemia the neoplastic cells had significantly weaker TGFα expression than seen in other forms of AML. The blast cells in CML-accelerated and blast phases were positive with similar expression to AML.ConclusionsTGFα is expressed in neoplastic myeloblasts and could, therefore, be used as blast cell biomarker in diagnostic haematopathology. In addition, TGFα immunohistochemistry may be of use in identifying a therapeutic target.

Early molecular response (EMR, BCR-ABL1 (IS)≤10% at 3 months) is a strong predictor of outcome in imatinib-treated chronic phase chronic myeloid leukemia (CP-CML) patients, but for patients who transform early, 3 months may be too late for effective therapeutic intervention. Here, we employed multiplex cytokine profiling of plasma samples to test newly diagnosed CP-CML patients who subsequently received imatinib treatment. A wide range of pro-inflammatory and angiogenesis-promoting cytokines, chemokines and growth factors were elevated in the plasma of CML patients compared with that of healthy donors. Most of these normalized after tyrosine kinase inhibitor treatment while others remained high in remission samples. Importantly, we identified TGF-α and IL-6 as novel biomarkers with high diagnostic plasma levels strongly predictive of subsequent failure to achieve EMR and deep molecular response, as well as transformation to blast crisis and event-free survival. Interestingly, high TGF-α alone can also delineate a poor response group raising the possibility of a pathogenic role. This suggests that the incorporation of these simple measurements to the diagnostic work-up of CP-CML patients may enable therapy intensity to be individualized early according to the cytokine-risk profile of the patient. Refereed/Peer-reviewed

© 2019 American Society of Human Genetics The occurrence of non-epileptic hyperkinetic movements in the context of developmental epileptic encephalopathies is an increasingly recognized phenomenon. Identification of causative mutations provides an important insight into common pathogenic mechanisms that cause both seizures and abnormal motor control. We report bi-allelic loss-of-function CACNA1B variants in six children from three unrelated families whose affected members present with a complex and progressive neurological syndrome. All affected individuals presented with epileptic encephalopathy, severe neurodevelopmental delay (often with regression), and a hyperkinetic movement disorder. Additional neurological features included postnatal microcephaly and hypotonia. Five children died in childhood or adolescence (mean age of death: 9 years), mainly as a result of secondary respiratory complications. CACNA1B encodes the pore-forming subunit of the pre-synaptic neuronal voltage-gated calcium channel Cav2.2/N-type, crucial for SNARE-mediated neurotransmission, particularly in the early postnatal period. Bi-allelic loss-of-function variants in CACNA1B are predicted to cause disruption of Ca2+ influx, leading to impaired synaptic neurotransmission. The resultant effect on neuronal function is likely to be important in the development of involuntary movements and epilepsy. Overall, our findings provide further evidence for the key role of Cav2.2 in normal human neurodevelopment.