Neha Bhatnagar

Idarucizumab for dabigatran overdose in a child

We report the first use of idarucizumab in the management of a massive dabigatran overdose in a child. Anticoagulation overdose is a challenging clinical scenario. Dabigatran, an oral direct thrombin inhibitor, is licensed for treatment and secondary prevention of venous thromboembolism and for stroke prevention in atrial fibrillation. Idarucizumab is a humanised monoclonal high affinity antibody fragment that specifically binds to, and neutralises dabigatran. It has recently been approved by the European Medicines Agency and the US Food and Drug Administration. A 15-year-old girl presented to the emergency department following the ingestion of between thirty and fifty 150-mg dabigatran tablets 4 h previously (dabigatran prescribed for her father). She had a history of self-harm with multiple emergency department attendances and had been recently expelled from school. She had no other significant medical history, no regular medications and no known drug allergies. She had minor gum bleeding and was haemodynamically stable (weight 67 kg). Initial blood tests showed normal full blood count, renal and liver function (creatinine 46 lmol/l). The coagulation profile was abnormal with an international normalised ratio (INR) of 9 1 and an activated partial thromboplastin ratio (APTR) of 4 8. No alcohol, paracetamol or salicylate was detected. Repeat coagulation tests locally confirmed prolongation of INR and APTR, fibrinogen 2 6 g/l and thrombin time (TT) reported as 53 s. Thrombin time is the most sensitive standard coagulation test to dabigatran and is sensitive to minimum levels of dabigatran. The activated partial thromboplastin time (APTT) is sensitive to dabigratran within the normal therapeutic range, but the increase in APTT starts to plateau beyond about 200 ng/ml dabigatran. The INR is, in general, less sensitive to dabigatran than the APTT and its degree of prolongation is reagent dependent (Stangier et al, 2007; van Ryn et al, 2010). In this case, the PT and APTR were consistent with the history of dabigatran overdose but the TT was not. However the patient and her family confirmed that she had taken dabigatran, and that there were no other anticoagulants in the house. She had a normal coagulation screen from a previous emergency department attendance. As she had no significant active bleeding, and the coagulation results did not match the reported history, the decision was made to administer 10 mg/kg tranexamic acid and 10 mg vitamin K intravenously. Prothrombin complex concentrate (PCC) was to be used if the patient developed significant bleeding and idarucizumab requested (not initially on site) to be available in case of need. Blood samples were couriered to the tertiary centre. These coagulation screen results were consistent with massive dabigatran overdose, with an unclottable TT (Table I). This was confirmed by a dabigatran assay (dilute thrombin time, Hemoclot assay) (Table I, Fig 1). Under standard conditions, this assay determines dabigatran levels between 30 and 500 ng/ml, however manual dilutions estimated initial dabigatran levels to be 1507–2040 ng/ml. The therapeutic peak dabigatran levels for patients taking 150 mg twice a day in the RE-LY trial was median 184 ng/ ml (range 74 3–383 ng/ml, 10–90 percentile) (Reilly et al, 2014), and the half-life of dabigatran in patients with normal renal function is 10–13 h. Our 15-year-old patient had 5–10 times supranormal levels and it was therefore estimated that it would take approximately 48 h for dabigatran to be

Transcriptional and epigenetic basis for restoration of G6PD enzymatic activity in human G6PD-deficient cells.

HDAC inhibitors (HDACi) increase transcription of some genes through histone hyperacetylation. To test the hypothesis that HDACi-mediated enhanced transcription might be of therapeutic value for inherited enzyme deficiency disorders, we focused on the glycolytic and pentose phosphate pathways (GPPPs). We show that among the 16 genes of the GPPPs, HDACi selectively enhance transcription of glucose 6-phosphate dehydrogenase (G6PD). This requires enhanced recruitment of the generic transcription factor Sp1, with commensurate recruitment of histone acetyltransferases and deacetylases, increased histone acetylation, and polymerase II recruitment to G6PD. These G6PD-selective transcriptional and epigenetic events result in increased G6PD transcription and ultimately restored enzymatic activity in B cells and erythroid precursor cells from patients with G6PD deficiency, a disorder associated with acute or chronic hemolytic anemia. Therefore, restoration of enzymatic activity in G6PD-deficient nucleated cells is feasible through modulation of G6PD transcription. Our findings also suggest that clinical consequences of pathogenic missense mutations in proteins with enzymatic function can be overcome in some cases by enhancement of the transcriptional output of the affected gene.

G371 Defining transient abnormal myelopoiesis (TAM) and silent tam in neonates with down syndrome

Background and aims Children with Down syndrome (DS) have a 150-fold-increased risk of acute myeloid leukaemia (ML-DS) in the first 5y of life (peak age 12–15 months). ML-DS is preceded by Transient Abnormal Myelopoiesis (TAM), a neonatal pre-leukaemic disorder unique to DS. Recent studies of clinically-diagnosed TAM show acquired mutations in the GATA1 gene in all cases. However, the true clinical spectrum of TAM is unknown since previous retrospective reports have not systematically evaluated blood films or GATA1 mutation status. The purpose of our study was to prospectively determine the clinical, haematological, molecular features and natural history of TAM. Methods Neonates with karyotypically-confirmed DS were prospectively enrolled to the Oxford-Imperial DS Cohort Study (OIDSCS) from October 2006. Detailed clinical and FBC/blood film data were matched to GATA1 mutational analysis by Sanger sequencing/Direct High Performance Liquid Chromatography (Ss/DHPLC). Targeted next-generation-sequencing (NGS) was used to determine clone size and/or detect small (<5%) mutant GATA1 clones. TAM was prospectively defined as: >10% peripheral blood blasts and GATA1 mutation(s) detected by Ss/DHPLC. Silent TAM was defined as: blasts <10% and GATA1 mutation (s) detected by Ss/DHPLC or NGS. Results Of 382 neonates recruited to OIDSCS by June 2014, 39 (10.2%) had TAM. Although no clinical features were specific for TAM, hepatosplenomegaly, pericardial/pleural effusion and skin rash were more common in TAM (p < 0.0001, p < 0.01, p < 0.05) than DS neonates without GATA1 mutations. The only haematological features specific for TAM were blasts >20% and WBC >45 × 109/L. Ten neonates with TAM and 8 without TAM had 11–20% blasts. In 163 DS neonates with blasts <10% screened by NGS, 33(20.2%) had small GATA1 clones (Silent TAM); their clinical and haematological features were indistinguishable from 130/163 without mutations. 4 neonates with TAM received low-dose chemotherapy and 1 died. ML-DS has developed in 4/39 TAM, 1/33 Silent TAM and no DS neonates without GATA1 mutations (median follow-up 57 months, range 18- >60). Conclusion In neonates with DS, acquired mutations in the GATA1 gene are common, often clinically and haematologically silent and confer a risk of ML-DS in TAM and Silent TAM.

Guidelines for the investigation and management of Transient Leukaemia of Down Syndrome.

Oliver Tunstall, Writing Group Chair, Neha Bhatnagar, Beki James, Alice Norton, Aengus S. O’Marcaigh, Tim Watts, Anne Greenough, Paresh Vyas, Irene Roberts and Michael Wright (BSH Guidelines Task Force Member), On behalf of the British Society for Haematology Bristol Royal Hospital for Children, University Hospitals Bristol NHS Trust, Bristol, John Radcliffe Hospital, Oxford University Hospitals NHS Trust and Oxford BRC Blood Theme, NIHR Oxford Biomedical Centre, Oxford, Leeds Children’s Hospital, Leeds Teaching Hospitals NHS Trust, Leeds, Birmingham Children’s Hospital NHS Trust, Birmingham, UK, Our Lady’s Children’s Hospital, Crumlin, Dublin, Evelina London Children’s Hospital, Guy’s and St Thomas’ NHS Trust, King’s College, London, MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, Paediatrics, Oxford University, Oxford, and West Hertfordshire Hospitals NHS Trust, Watford, UK

Congenital acute myeloid leukaemia with KMT2A rearrangement

A full-term baby born to non-consanguineous parents was ‘mottled’ at birth. On examination she had extensive ‘blueberry muffin’ lesions (top left), marked hepatosplenomegaly and moderate respiratory distress. She had no clinical features of Down syndrome. Her full blood count showed Hb 165 g/l, WBC 271 9 10/l and platelets 171 9 10/l. Her peripheral blood film showed numerous monoblasts and promonocytes (top center). Immunophenotype was consistent with acute monoblastic leukaemia (HLA-DR+, cytoplasmic myeloperoxidase+, CD33+, CD14+, CD64+, CD15+ and CD11c+). Fluorescence in situ hybridisation (FISH) of interphase cells was carried out using the Vysis MLL dual-colour break-apart probe, which maps to 11q23. The cells exhibited an abnormal signal pattern of one red, one green and one red/green fusion, indicating the presence of a KMT2A (MLL) gene rearrangement (top right). A G-banded karyotype (bottom) showed an abnormal karyotype of 46 chromosomes with a derivative chromosome 11 and a derivative chromosome 19. A possible mechanism for this rearrangement is a reciprocal translocation between the short arms of chromosome 11 and 19 at breakpoints p11.2 and p11.2 followed by an inversion of the derivative chromosome 11, at the 11q23.3 KMT2A locus. It was not possible to ascertain the partner gene involved in this rearrangement. No rearrangement of NPM1 or FLT3-internal tandem duplication was found. She was admitted to paediatric intensive care for close monitoring and required haemostatic support to correct a coagulopathy. She received chemotherapy for acute myeloid leukaemia (AML) with mitoxantrone and cytarabine with rapid reduction in her white cell count and gradual resolution of the rash. She was in morphological remission and negative for minimal residual disease on flow cytometry (<0 1%) following her first cycle of chemotherapy and proceeded to have further chemotherapy. Congenital leukaemia is a rare disorder that accounts for about 1% of paediatric leukaemias and has an estimated prevalence of 1/1 000 000 neonates. The majority of neonatal leukaemias are acute myeloid leukaemia and the most common subtype is acute monoblastic leukaemia. Typical clinical features include leukaemia cutis as a result of leukaemic infiltration of the dermis (‘blueberry muffin’ rash), hepatosplenomegaly and cardiac failure. Chromosomal rearrangements are often found, with KMT2A rearrangements being by far the most common. The prognosis remains poor.