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Shu M, Malcolmson C, Bouskill V, Stain AM, Wakefield C, Blanchette VS, Carcao MD. Unravelling the effect of blood group on FVIII:C levels and response to DDAVP in 20 males with a single genotype (Twillingate Variant) causing Haemophilia A. Haemophilia 2024; 30:116-122. [PMID: 38037243 DOI: 10.1111/hae.14896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 10/21/2023] [Accepted: 10/24/2023] [Indexed: 12/02/2023]
Abstract
INTRODUCTION The genetic variant responsible for haemophilia A (HA) significantly impacts endogenous coagulant factor VIII (FVIII:C) level, thus impacting DDAVP responsiveness. Blood group (BG) also impacts FVIII:C levels, but this is difficult to evaluate in a genetically heterogeneous population. Canada has a large cohort of mild-moderate HA due to a single point variant: c.6104T>C, p.Val2035Ala-the Twillingate variant. AIM To evaluate the impact of BG on endogenous FVIII:C levels and DDAVP responsiveness in a single genotype of mild-moderate HA. METHODS This was a retrospective, single-centre study. BG and FVIII:C levels were obtained for males with the Twillingate variant. One-hour absolute and fold increases in FVIII:C post-DDAVP were calculated. T-tests and Mann-Whitney U tests were used to compare FVIII:C levels and DDAVP challenge variables between individuals according to BGs (O vs. non-O). RESULTS Twenty males were included. There were significant differences between BGs (O vs. non-O) in their lowest FVIII:C level at age <12 years (medians: 0.05 vs. 0.08 IU/mL; P = .05). Fifteen subjects underwent DDAVP challenges. Mean 1-h FVIII:C were 0.29 (O BG) versus 0.41 IU/mL (non-O BG); P = .04. There were no significant differences between BGs (O vs. non-O) in mean absolute FVIII:C increase (0.20 vs. 0.27 IU/mL; P = .10) and FVIII:C fold increase (3.3-fold vs. 3.8-fold; P = .51). CONCLUSION In HA subjects with an identical genotype, BG significantly impacts baseline FVIII:C levels and FVIII:C levels post-DDAVP, but does not impact absolute and fold increases in FVIII:C with DDAVP.
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Affiliation(s)
- Michael Shu
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Caroline Malcolmson
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Vanessa Bouskill
- Department of Nursing, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Ann Marie Stain
- Department of Nursing, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Cindy Wakefield
- Department of Nursing, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Victor S Blanchette
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Manuel D Carcao
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
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2
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Chrisentery-Singleton T, Boggio LN, Carcao MD, Ibrahimi S, Khan O, Mahajerin A, Rajasekhar A, Sharma V, Steele M, Torres M, Rodino FJ, Carpenter SL. Long-term follow-up of patients with congenital thrombotic thrombocytopenia purpura receiving a plasma-derived factor VIII (Koate) that contains ADAMTS13. Haemophilia 2023; 29:1638-1645. [PMID: 37855744 DOI: 10.1111/hae.14891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/05/2023] [Accepted: 10/10/2023] [Indexed: 10/20/2023]
Abstract
BACKGROUND Hereditary thrombotic thrombocytopenia purpura (hTTP) is an ultra-rare disorder resulting from an inherited deficiency of ADAMTS13, a von Willebrand factor (VWF)-cleaving metalloprotease. The plasma-derived factor VIII/VWF Koate (FVIII/VWFKoate ) has been shown to contain ADAMTS13, allowing for its use to treat hTTP at home by the patient/caregiver. AIM Based on prior demonstration of safe and effective use of FVIII/VWFKoate in eight patients with hTTP, we conducted a retrospective study to gather additional data regarding the use of FVIII/VWFKoate for hTTP. METHODS This was a multicentre, retrospective, noninterventional chart review of patients who had received FVIII/VWFKoate for the management of hTTP. Data collected included demographics, medical history, relevant family history, past use and tolerability of fresh frozen plasma, and details regarding FVIII/VWFKoate therapy. RESULTS The cohort included 11 patients (seven males, four females) with hTTP, ranging in age at study entry from 2 to 28 years. The average duration of FVIII/VWFKoate therapy was 4.8 years (range, 0.5-6.5 years). Among nine patients using FVIII/VWFKoate as prophylaxis, the normalized annual rate of breakthrough TTP episodes ranged from 0.2 to 1.1 episodes/year. All nine patients who received FVIII/VWFKoate prophylaxis had thrombocytopenia recorded at baseline, while eight (88.9%) did not have thrombocytopenia after using FVIII/VWFKoate . There was one AE (unspecified) attributed to FVIII/VWFKoate . CONCLUSION These data suggest that FVIII/VWFKoate is a safe and well-tolerated source of the missing ADAMTS13 enzyme in patients with hTTP, producing a marked reduction in thrombocytopenia prevalence, low frequency of TTP episodes, and with the added benefit of self- or caregiver-administration.
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Affiliation(s)
| | - Lisa N Boggio
- Rush Hemophilia & Thrombophilia Center, Rush University Medical Center, Chicago, Illinois, USA
| | - Manuel D Carcao
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, Toronto, ON, Canada
| | - Sami Ibrahimi
- OUHSC/Stephenson Cancer Center, Oklahoma City, Oklahoma, USA
| | - Osman Khan
- University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Arash Mahajerin
- Children's Hospital of Orange County, Orange, California, USA
| | - Anita Rajasekhar
- University of Florida - Shands Hospital, Gainesville, Florida, USA
| | - Vivek Sharma
- University of Louisville, Louisville, Kentucky, USA
| | | | - Marcela Torres
- Department of Hematology, Cook Children's Medical Center, Fort Worth, Texas, USA
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Lunati-Rozie A, Janin A, Faubert E, Nony S, Renoux C, Carcao MD, Fanen P, Funalot B, Mansour-Hendili L, Joly P. Use of minigene assays as a useful tool to confirm the pathogenic role of intronic variations of the ANK1 gene: Report of two cases of hereditary spherocytosis. Br J Haematol 2023; 201:e46-e49. [PMID: 36928866 DOI: 10.1111/bjh.18760] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/21/2023] [Accepted: 03/07/2023] [Indexed: 03/18/2023]
Affiliation(s)
- Ariane Lunati-Rozie
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, Créteil, France.,Université Paris-Est Créteil, INSERM, IMRB, Créteil, France
| | - Alexandre Janin
- Institut NeuroMyoGène, Laboratoire Physiopathologie et Génétique du Neurone et du Muscle, CNRS UMR 5261 -INSERM U1315 - Université de Lyon - Université Claude Bernard Lyon 1, Lyon, France.,Service de Biochimie et de Biologie Moléculaire, Centre de Biologie et de Pathologie Est, Hospices Civils de Lyon, Bron, France
| | - Emmanuelle Faubert
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, Créteil, France.,Université Paris-Est Créteil, INSERM, IMRB, Créteil, France
| | - Severine Nony
- Service de Biochimie et de Biologie Moléculaire, Centre de Biologie et de Pathologie Est, Hospices Civils de Lyon, Bron, France
| | - Céline Renoux
- Service de Biochimie et de Biologie Moléculaire, Centre de Biologie et de Pathologie Est, Hospices Civils de Lyon, Bron, France.,Laboratoire Interuniversitaire de Biologie de la Motricité (LIBM) EA7424, Equipe "Biologie vasculaire et du globule rouge", Université Claude Bernard Lyon 1, COMUE, Lyon, France
| | - Manuel D Carcao
- Paediatric Haematology and Oncology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Pascale Fanen
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, Créteil, France.,Université Paris-Est Créteil, INSERM, IMRB, Créteil, France
| | - Benoît Funalot
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, Créteil, France.,Université Paris-Est Créteil, INSERM, IMRB, Créteil, France
| | - Lamisse Mansour-Hendili
- Département de Biochimie-Biologie Moléculaire, Pharmacologie, Génétique Médicale, AP-HP, Hôpitaux Universitaires Henri Mondor, Créteil, France.,IMRB Equipe Pirenne, Laboratoire d'excellence LABEX GRex, Université Paris-Est Créteil, Créteil, France
| | - Philippe Joly
- Service de Biochimie et de Biologie Moléculaire, Centre de Biologie et de Pathologie Est, Hospices Civils de Lyon, Bron, France.,Laboratoire Interuniversitaire de Biologie de la Motricité (LIBM) EA7424, Equipe "Biologie vasculaire et du globule rouge", Université Claude Bernard Lyon 1, COMUE, Lyon, France.,Laboratoire d'Excellence du Globule Rouge, Labex GR-Ex, Université Paris, PRES Sorbonne, Paris, France
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4
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Rawley O, Swystun LL, Brown C, Nesbitt K, Rand M, Hossain T, Klaassen R, James PD, Carcao MD, Lillicrap D. Novel cysteine substitution p.(Cys1084Tyr) causes variable expressivity of qualitative and quantitative VWF defects. Blood Adv 2022; 6:2908-2919. [PMID: 35020809 PMCID: PMC9092401 DOI: 10.1182/bloodadvances.2021005928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 11/23/2021] [Indexed: 11/20/2022] Open
Abstract
von Willebrand factor (VWF) is an extremely cysteine-rich multimeric protein that is essential for maintaining normal hemostasis. The cysteine residues of VWF monomers form intra- and intermolecular disulfide bonds that regulate its structural conformation, multimer distribution, and ultimately its hemostatic activity. In this study, we investigated and characterized the molecular and pathogenic mechanisms through which a novel cysteine variant p.(Cys1084Tyr) causes an unusual, mixed phenotype form of von Willebrand disease (VWD). Phenotypic data including bleeding scores, laboratory values, VWF multimer distribution, and desmopressin response kinetics were investigated in 5 members (2 parents and 3 daughters) of a consanguineous family. VWF synthesis and secretion were also assessed in a heterologous expression system and in a transient transgenic mouse model. Heterozygosity for p.(Cys1084Tyr) was associated with variable expressivity of qualitative VWF defects. Heterozygous individuals had reduced VWF:GPIbM (<0.40 IU/mL) and VWF:CB (<0.35 IU/mL), as well as relative reductions in high-molecular-weight multimers, consistent with type 2A VWD. In addition to these qualitative defects, homozygous individuals also displayed reduced factor VIII (FVIII):C/VWF:Ag, leading to very low FVIII levels (0.03-0.1 IU/mL) and reduced VWF:Ag (<0.40 IU/mL) and VWF:GPIbM (<0.30 IU/mL). Accelerated VWF clearance and impaired VWF secretion contributed to the fully expressed homozygous phenotype with impaired secretion arising because of disordered disulfide connectivity.
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Affiliation(s)
- Orla Rawley
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
| | - Laura L. Swystun
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
| | - Christine Brown
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
| | - Kate Nesbitt
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
| | - Margaret Rand
- Division of Hematology/Oncology, Department of Pediatrics, Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - Taneya Hossain
- Division of Hematology/Oncology, Department of Pediatrics, Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - Robert Klaassen
- Department of Pediatrics, University of Ottawa, Ottawa, ON, Canada; and
| | - Paula D. James
- Department of Medicine, Queen’s University, Kingston, ON, Canada
| | - Manuel D. Carcao
- Division of Hematology/Oncology, Department of Pediatrics, Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - David Lillicrap
- Molecular Hemostasis Research Group, Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, Canada
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5
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Blanchette VS, Zunino L, Grassmann V, Barnes C, Carcao MD, Curtin J, Jackson S, Khoo L, Komrska V, Lillicrap D, Morfini M, Romanova G, Stephens D, Zapotocka E, Rand ML, Blatny J. A Practical, One-Clinic Visit Protocol for Pharmacokinetic Profile Generation with the ADVATE myPKFiT Dosing Tool in Severe Hemophilia A Subjects. Thromb Haemost 2021; 121:1326-1336. [PMID: 33506480 PMCID: PMC8494515 DOI: 10.1055/a-1376-0970] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Standard pharmacokinetic (PK) assessments are demanding for persons with hemophilia A, requiring a 72-hour washout and 5 to 11 timed blood samples. A no-washout, single-clinic visit, sparse sampling population PK (PPK) protocol is an attractive alternative. Here, we compared PK parameters obtained with a traditional washout, 6-sampling time point PPK protocol with a no-washout, single-clinic visit, reverse 2-sampling time point PPK protocol in persons with severe hemophilia A (SHA) receiving ADVATE. A total of 39 inhibitor-negative males with SHA (factor VIII activity [FVIII:C] < 2%) were enrolled in a prospective sequential design PK study. Participants completed a washout, 6-sampling time point PPK protocol as well as a no-washout, reverse 2-sampling time point protocol, with samples taken during a single 3-hour clinic visit 24 hours post home infusion of FVIII and then 3 hours post infusion in clinic. FVIII:C levels were analyzed by one-stage and chromogenic assays; blood group and von Willebrand factor antigen (VWF:Ag) were determined; and PK parameters were analyzed using the ADVATE myPKFiT dosing tool. There was moderate to almost perfect agreement for the PK parameters obtained with the 2- and the 6- point PPK protocols using a one-stage FVIII:C assay and a substantial to almost perfect agreement using a chromogenic FVIII:C assay. Significant associations between specific PK parameters and blood group and VWF:Ag were observed. The no-washout, single-clinic visit, reverse 2-sampling time point PPK protocol can be used in the routine clinical setting since it demonstrates sufficient accuracy compared with the more demanding and less practical washout, 6-sampling time point PPK protocol in persons with SHA receiving ADVATE.
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Affiliation(s)
- Victor S Blanchette
- Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Laura Zunino
- Child Health Evaluative Sciences, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Viviane Grassmann
- Child Health Evaluative Sciences, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Chris Barnes
- Haematology Department, The Royal Children's Hospital Melbourne, Victoria, Australia.,Haematology Research, Murdoch Children's Research Institute, Victoria, Australia
| | - Manuel D Carcao
- Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Child Health Evaluative Sciences, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Julie Curtin
- Department of Haematology, The Children's Hospital at Westmead, Sydney, Australia.,Department of Paediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Shannon Jackson
- Division of Haematology, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Liane Khoo
- Haematology Department, Royal Prince Alfred Hospital, NSW Health Pathology, Sydney, Australia
| | - Vladimir Komrska
- Department of Paediatric Haematology and Oncology, University Hospital Motol, Prague, Czech Republic
| | - David Lillicrap
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada
| | | | - Gabriela Romanova
- Department of Clinical Haematology, University Hospital Brno, Brno, Czech Republic.,Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Derek Stephens
- Department of Clinical Research Services, The Hospital for Sick Children, Toronto, Canada
| | - Ester Zapotocka
- Department of Paediatric Haematology and Oncology, University Hospital Motol, Prague, Czech Republic
| | - Margaret L Rand
- Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada.,Translational Medicine, Research Institute, The Hospital for Sick Children, Toronto, Canada.,Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.,Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.,Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | - Jan Blatny
- Faculty of Medicine, Masaryk University, Brno, Czech Republic.,Department of Paediatric Haematology, University Hospital Brno, Brno, Czech Republic
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6
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Tole S, Dhir P, Pugi J, Drury LJ, Butchart S, Fantauzzi M, Langer JC, Baker JM, Blanchette VS, Kirby-Allen M, Carcao MD. Genotype-phenotype correlation in children with hereditary spherocytosis. Br J Haematol 2020; 191:486-496. [PMID: 32436265 DOI: 10.1111/bjh.16750] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/17/2020] [Accepted: 04/23/2020] [Indexed: 11/27/2022]
Abstract
Hereditary spherocytosis (HS) is a common inherited haemolytic anaemia attributed to disturbances in five different red cell membrane proteins. We performed a retrospective study of 166 children with HS and describe the clinical phenotype according to the genotype. In 160/166 (97%) children with HS a disease-causing mutation was identified. Pathogenic variants in ANK1, SPTB, SLC4A1 and SPTA1 were found in 49%, 33%, 13% and 5% of patients. Children with SLC4A1-HS had the mildest phenotype, showing the highest haemoglobin (P < 0·001), lowest reticulocyte counts (P < 0·001) and lowest unconjugated bilirubin levels (P = 0·006), and none required splenectomy in childhood (P < 0·001). Conversely, children with autosomal recessive SPTA1-HS had the most severe clinical phenotype, with almost all patients undergoing splenectomy in early childhood. Patients with ANK1 and SPTB variants showed a similar clinical phenotype. Within each gene, variant type or location did not predict disease severity or likelihood of splenectomy. Among patients with a genetic diagnosis, 47 (29%) underwent splenectomy (23 partial; 24 total) while 57 (36%) underwent cholecystectomy. Total splenectomy led to greater improvements in haemoglobin (P = 0·02). Select use of genetic testing (especially in patients without a family history) may help predict clinical phenotype in childhood and guide family counselling.
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Affiliation(s)
- Soumitra Tole
- Department of Paediatrics, Division of Haematology/Oncology, Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Paediatrics, Division of Haematology/Oncology, Children's Hospital, London Health Sciences Centre, London, Ontario, Canada.,Western University, London, Ontario, Canada
| | - Priya Dhir
- Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Jakob Pugi
- Department of Paediatrics, Division of Haematology/Oncology, Hospital for Sick Children, Toronto, Ontario, Canada
| | | | - Sheila Butchart
- Department of Nursing, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michelle Fantauzzi
- Department of Nursing, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Jacob C Langer
- Department of Surgery, Hospital for Sick Children and Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Jillian M Baker
- Department of Paediatrics, Division of Haematology/Oncology, Hospital for Sick Children, Toronto, Ontario, Canada.,Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Pediatrics, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Victor S Blanchette
- Department of Paediatrics, Division of Haematology/Oncology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Melanie Kirby-Allen
- Department of Paediatrics, Division of Haematology/Oncology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Manuel D Carcao
- Department of Paediatrics, Division of Haematology/Oncology, Hospital for Sick Children, Toronto, Ontario, Canada.,Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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Abstract
Dieulafoy's lesion (DL) is a small gastrointestinal (GI) mucosal erosion due to an abnormally large caliber and persistent submucosal arteriole. Typically occurring in adults, they are an extremely rare cause of GI bleeding in pediatrics. We report a case of multiple jejunal DLs in a 9-year-old girl with posterior fossa brain malformations, hemangiomas, arterial lesions, cardiac abnormalities, eye abnormalities (PHACE) syndrome, and the first described use of rapamycin in the treatment of pediatric DLs.
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Affiliation(s)
- Lukas Kieswetter
- Department of Paediatrics, McMaster University, Hamilton, Ontario, Canada
| | - Thomas D Walters
- Division of Gastroenterology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Irene Lara-Corrales
- Division of Dermatology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Manuel D Carcao
- Division of Haematology/Oncology, Department of Paediatrics, Child Health Evaluative Sciences, Research Institute, Toronto, Ontario, Canada
| | - Bo Ngan
- Division of Pathology, Department of Pediatric Laboratory, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Elena Pope
- Division of Dermatology, Hospital for Sick Children, Toronto, Ontario, Canada
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8
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Tole S, Fantauzzi M, Cottingham D, Amaral JG, John PR, Lara-Corrales I, Pope E, Carcao MD. The use of rapamycin to treat vascular tumours and malformations: A single-centre experience. Paediatr Child Health 2019; 26:e25-e32. [PMID: 34434292 DOI: 10.1093/pch/pxz090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Accepted: 04/01/2019] [Indexed: 11/12/2022] Open
Abstract
Objectives To assess the safety and efficacy of rapamycin in treating children with vascular tumours and malformations. Study design We performed a retrospective review at a large tertiary care paediatric centre to assess the efficacy and safety of using rapamycin to treat vascular tumours and malformations. Response to therapy was defined by patient-reported symptom improvement, radiological reduction in size of lesions, and/or improvement of laboratory parameters. Results Forty-two patients (7 with vascular tumours and 35 with vascular malformations) have been treated with rapamycin. Despite 33 of 42 patients being diagnosed in the first year of life, the median age of initiating rapamycin was 11 years. Of the 38 children treated for a minimum of 4 months, 29 (76%) exhibited a clinical response. Twenty-one patients had follow-up imaging studies and of these, 16 (76%) had radiographic decrease in lesion size. Median time to demonstration of response was 49 days. All five children with vascular tumours and all three children with vascular malformations under the age of 4 years showed a clinical response. Response rate was lower for children ≥ 4 years of age (0/2, 0% for vascular tumours; 21/28, 75% for vascular malformations). No patient experienced an infection directly related to rapamycin or discontinued rapamycin due to toxicity. Conclusions Rapamycin is safe and efficacious in most children with select vascular tumours and malformations. Young children appear to respond better, suggesting that early initiation of rapamycin should be considered.
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Affiliation(s)
- Soumitra Tole
- Department of Paediatrics, Division of Haematology/Oncology, Hospital for Sick Children, Toronto, Ontario
| | | | - Diana Cottingham
- Department of Social Work, Hospital for Sick Children, Toronto, Ontario
| | - Joao G Amaral
- Department of Diagnostic Imaging, Division of Interventional Radiology, Hospital for Sick Children, Toronto, Ontario
| | - Philip R John
- Department of Diagnostic Imaging, Division of Interventional Radiology, Hospital for Sick Children, Toronto, Ontario
| | - Irene Lara-Corrales
- Department of Paediatrics, Section of Dermatology, Hospital for Sick Children, Toronto, Ontario
| | - Elena Pope
- Department of Paediatrics, Section of Dermatology, Hospital for Sick Children, Toronto, Ontario
| | - Manuel D Carcao
- Department of Paediatrics, Division of Haematology/Oncology, Hospital for Sick Children, Toronto, Ontario.,Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, Toronto, Ontario
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9
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Egan G, Pluthero FG, Bouskill V, Hilliard P, Drury LJ, Carcao MD, Kahr WHA. Abnormal fibrinolysis recognized by thromboelastography in a case of severe bleeding with normal coagulation and platelet function, leads to detection of a novel SERPINF2 variant causing severe alpha-2-antiplasmin deficiency. Br J Haematol 2019; 186:e198-e201. [PMID: 31282989 DOI: 10.1111/bjh.16077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Grace Egan
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - Fred G Pluthero
- Cell Biology Program, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Vanessa Bouskill
- Department of Nursing, The Hospital for Sick Children, Toronto, ON, Canada
| | - Pamela Hilliard
- Child Health Evaluative Sciences Program, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | | | - Manuel D Carcao
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada.,Child Health Evaluative Sciences Program, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Walter H A Kahr
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada.,Cell Biology Program, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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10
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Carcao MD, Chelle P, Clarke E, Kim L, Tiseo L, Morfini M, Hossain T, Rand ML, Brown C, Edginton AN, Lillicrap D, Iorio A, Blanchette VS. Comparative pharmacokinetics of two extended half-life FVIII concentrates (Eloctate and Adynovate) in adolescents with hemophilia A: Is there a difference? J Thromb Haemost 2019; 17:1085-1096. [PMID: 31038793 DOI: 10.1111/jth.14469] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 04/09/2019] [Accepted: 04/19/2019] [Indexed: 01/19/2023]
Abstract
Essentials The PK parameters of Eloctate vs Adynovate were compared using one-stage and chromogenic assays in 25 boys (12-18 years). The FVIII levels were taken at 3, 24, 48, and 72 hours following a dose of either FVIII; levels analyzed by WAPPS PK program. The PK profiles (half-life, clearance, and time to 5%, 3%, and 1%) were not statistically different for the two EHL FVIIIs. The significant interpatient variability in PK is mainly related to VWF levels (and blood group). BACKGROUND A head-to-head comparison of the pharmokinetcs (PK) of extended half-life (EHL) factor VIII (FVIII) concentrates in the same subjects has not been reported. Recently, boys (ages 12-18 years) with hemophilia A in Canada were required to switch from Eloctate to Adynovate. OBJECTIVES Compare the PK profiles of Eloctate vs Adynovate in the same boys. METHODS Boys switching from Eloctate to Adynovate prophylaxis had FVIII levels sampled at 3, 24, 48, and 72 hours following a regular prophylactic infusion of Eloctate and then 1-3 months later, of Adynovate. Testing was done by one-stage assay (OSA) and chromogenic assay (CA). The PK parameters were determined with the Web Accessible Population Pharmacokinetic Service (WAPPS)-Hemo PK tool. RESULTS Twenty-five boys (mean age 15.3 years; range: 12.1-18.4; 9 O blood group) underwent switching. Mean (range) terminal half-lives with the OSA were 16.1 hours (10.4 to 23.4; Eloctate) and 16.7 hours (11.0 to 23.6; Adynovate) (NS). With the CA, these were 18.0 hours (12.0 to 25.5; Eloctate) and 16.0 hours (10.3 to 22.9; Adynovate) (P = 0.001). There were no significant differences between the two EHL-FVIIIs in clearance, area under the concentration vs time curve (AUC), Vss, or time for FVIII levels to drop to 5%, 3%, and 1%. At the 72-h time point, mean observed FVIII levels following a mean dose of 39.3 IU/kg of Eloctate were 4.4% (OSA) and 4.4% (CA). For Adynovate, these were 5.1% (OSA) and 5.3% (CA) following similar doses. There was considerable interpatient variation in PK, mainly explained by differences in blood group/von Willebrand factor (VWF) levels. CONCLUSIONS Eloctate and Adynovate have almost identical PK parameters. When switching from one to another no prophylaxis regimen change is needed.
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Affiliation(s)
- Manuel D Carcao
- Division of Haematology/Oncology, Department of Paediatrics and Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Pierre Chelle
- School of Pharmacy, University of Waterloo, Waterloo, ON, Canada
| | - Emily Clarke
- Department of Nursing, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Lussia Kim
- Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Laura Tiseo
- Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | | | - Taneya Hossain
- Translational Medicine, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
| | - Margaret L Rand
- Division of Haematology/Oncology, Department of Paediatrics and Translational Medicine, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Departments of Laboratory Medicine & Pathobiology and Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Christine Brown
- Department of Pathology & Molecular Medicine, Queen's University, Kingston, ON, Canada
| | | | - David Lillicrap
- Department of Pathology & Molecular Medicine, Queen's University, Kingston, ON, Canada
| | - Alfonso Iorio
- McMaster-Bayer Endowed Research Chair for Clinical Epidemiology of Congenital Bleeding Disorders, Department of Medicine, McMaster University, Hamilton, ON, Canada
- Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, ON, Canada
| | - Victor S Blanchette
- Division of Haematology/Oncology, Department of Paediatrics and Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
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11
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Abstract
The mainstay of hemophilia management has been the regular, prophylactic infusion of missing coagulation factors VIII/IX. This approach is limited by the need for frequent intravenous infusions, high cost, limited availability, and the development of inhibitory antibodies to factors VIII/IX. Numerous recent breakthroughs are addressing many of these limitations. These include the development of extended half-life factors that require less frequent infusions and the development of various novel agents that can be given subcutaneously and infrequently, including FVIII-mimetic antibody and downregulators of natural anticoagulants. Finally, gene therapy is set to offer patients a possibility for a cure.
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Affiliation(s)
- Marie-Claude Pelland-Marcotte
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto M5G 1X8, Canada.
| | - Manuel D Carcao
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto M5G 1X8, Canada; Child Health Evaluative Sciences, Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto M5G 1X8, Canada
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12
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Pelland-Marcotte MC, Humpl T, James PD, Rand ML, Bouskill V, Reyes JT, Bowman ML, Carcao MD. Idiopathic pulmonary arterial hypertension - a unrecognized cause of high-shear high-flow haemostatic defects (otherwise referred to as acquired von Willebrand syndrome) in children. Br J Haematol 2018; 183:267-275. [PMID: 30141279 DOI: 10.1111/bjh.15530] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 06/21/2018] [Indexed: 02/06/2023]
Abstract
Acquired von Willebrand syndrome (AVWS) is reported in high-flow high-shear congenital cardiac disorders. We hypothesized that the narrowed pulmonary vasculature in idiopathic pulmonary arterial hypertension (IPAH) may induce AVWS. We conducted a cross-sectional evaluation of children with IPAH. Patients with bleeding symptoms and/or laboratory abnormalities (thrombocytopenia, anomalies in coagulation screening tests) were tested in-depth for haemostatic defects. Fourteen children were followed with IPAH of which 8 were eligible. Four children exhibited abnormal bleeding scores (International Society on Thrombosis and Haemostasis Bleeding Assessment Tool: 3-5). All 8 patients showed very prolonged platelet function analyser (PFA)-100 closure times. Six children demonstrated either mild thrombocytopenia or low-normal von Willebrand factor (VWF) antigen (VWF:Ag) or VWF activity [mean (range), in iu/dl: VWF:Ag: 70 (61-91); VWF activity: 57 (34-70)]. Average VWF collagen binding capacity (VWF:CB) was 64 iu/dl (range: 53-123 iu/dl), with low-normal VWF activity/VWF:Ag or VWF:CB/VWF:Ag ratios occurring in five patients. All children had normal multimers distribution patterns. One patient underwent a lung transplantation, with normalization of haemostatic abnormalities post-surgery. Overall, 8 out of 14 children with IPAH had mild to moderate bleeding symptoms and/or laboratory abnormalities in keeping with AVWS. Normalization of the haemostatic defects following lung transplantation and lack of family history of bleeding attests to the acquired nature of their defects.
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Affiliation(s)
- Marie-Claude Pelland-Marcotte
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - Tilman Humpl
- Division of Cardiology, Department of Paediatrics, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - Paula D James
- Department of Medicine, Queen's University, Kingston, ON, Canada
| | - Margaret L Rand
- Division of Haematology/Oncology, Translational Medicine, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada.,Departments of Laboratory Medicine & Pathobiology, Biochemistry and Paediatrics, University of Toronto, Toronto, ON, Canada
| | - Vanessa Bouskill
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada.,Department of Nursing, The Hospital for Sick Children, Toronto, ON, Canada
| | - Janette T Reyes
- Division of Cardiology, Department of Paediatrics, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada.,Department of Nursing, The Hospital for Sick Children, Toronto, ON, Canada
| | - Mackenzie L Bowman
- Department of Medicine, Queen's University, Kingston, ON, Canada.,Department of Pathology and Molecular Medicine, Queen's University, Kingston, ON, Canada
| | - Manuel D Carcao
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada.,Child Health Evaluative Sciences, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
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13
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Abstract
Homozygosity/compound heterozygosity for loss of function mutations in neurobeachin-like 2 (NBEAL2) is causative for Gray platelet syndrome (GPS; MIM #139090), characterized by thrombocytopenia and large platelets lacking α-granules and cargo. Most GPS-associated NBEAL2 mutations generate nonsense codons; frameshifts causing premature translation termination and/or changes in mRNA splicing have also been observed. Data regarding NBEAL2 protein expression in GPS patients is limited. We observed absence of NBEAL2 in platelets from GPS patients with 3 different genotypes, and reduced/truncated platelet NBEAL2 has been reported for others. GPS is commonly associated with mild bleeding, but lifethreatening bleeding has been reported in some cases. A common long-term complication in GPS patients is myelofibrosis; splenomegaly is less common but sometimes of sufficient severity to merit splenectomy. Like GPS patients, mice lacking NBEAL2 expression exhibit macrothrombocytopenia, deficiency of platelet α-granules, splenomegaly, myelofibrosis, impaired platelet function and abnormalities in megakaryocyte development. Animal studies have also reported impaired platelet function in vivo using laser injury and thrombo-inflammation models. NBEAL2 is a large gene with 54 exons, and several putative functional domains have been identified in NBEAL2, including PH (pleckstrin homology) and BEACH (beige and Chediak-Higashi) domains shared with other members of a protein family that includes LYST and LRBA, also expressed by hematopoietic cells. Potential NBEAL2-interacting proteins have recently been identified, and it is expected that current and future efforts will reveal the cellular mechanisms by which NBEAL2 facilitates platelet development and supports hemostatic function.
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Affiliation(s)
- Fred G Pluthero
- a Cell Biology Program , Research Institute, Hospital for Sick Children , Toronto , ON , Canada
| | - Jorge Di Paola
- b Department of Pediatrics and Human Genetics and Genomics Program , University of Colorado, Anschutz Medical Campus , Aurora , CO , USA
| | - Manuel D Carcao
- c Division of Haematology/Oncology, Department of Paediatrics , University of Toronto and The Hospital for Sick Children , Toronto , ON , Canada.,d Child Health Evaluative Sciences , Research Institute, Hospital for Sick Children , Toronto , ON , Canada
| | - Walter H A Kahr
- a Cell Biology Program , Research Institute, Hospital for Sick Children , Toronto , ON , Canada.,c Division of Haematology/Oncology, Department of Paediatrics , University of Toronto and The Hospital for Sick Children , Toronto , ON , Canada.,e Department of Biochemistry , University of Toronto , Toronto , ON , Canada
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14
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Labarque V, Perinparajah V, Bouskill V, Stain AM, Wakefield C, Manuel C, Blanchette VS, James PD, Lillicrap D, Carcao MD. Utility of factor VIII and factor VIII to von Willebrand factor ratio in identifying 277 unselected carriers of hemophilia A. Am J Hematol 2017; 92:E94-E96. [PMID: 28249352 DOI: 10.1002/ajh.24709] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 02/25/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Veerle Labarque
- Division of Haematology/Oncology; Department of Paediatrics, Hospital for Sick Children; Toronto Canada
| | - Vanitha Perinparajah
- Division of Haematology/Oncology; Department of Paediatrics, Hospital for Sick Children; Toronto Canada
| | - Vanessa Bouskill
- Department of Nursing; Hospital for Sick Children; Toronto Canada
| | - Ann Marie Stain
- Department of Nursing; Hospital for Sick Children; Toronto Canada
| | - Cindy Wakefield
- Department of Nursing; Hospital for Sick Children; Toronto Canada
| | - Cecilia Manuel
- Division of Haematology/Oncology; Department of Paediatrics, Hospital for Sick Children; Toronto Canada
| | - Victor S. Blanchette
- Division of Haematology/Oncology; Department of Paediatrics, Hospital for Sick Children; Toronto Canada
- Child Health Evaluative Science, Research Institute, Hospital for Sick Children, University of Toronto; Toronto Canada
| | - Paula D. James
- Department of Medicine; Queen's University; Kingston Canada
| | - David Lillicrap
- Department of Pathology & Molecular Medicine; Queen's University; Kingston Canada
| | - Manuel D. Carcao
- Division of Haematology/Oncology; Department of Paediatrics, Hospital for Sick Children; Toronto Canada
- Child Health Evaluative Science, Research Institute, Hospital for Sick Children, University of Toronto; Toronto Canada
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15
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Al-Battat S, Rand ML, Bouskill V, Lau W, Blanchette VS, Kahr WHA, Rivard GE, Carcao MD. Glanzmann thrombasthenia platelets compete with transfused platelets, reducing the haemostatic impact of platelet transfusions. Br J Haematol 2017; 181:410-413. [PMID: 28466602 DOI: 10.1111/bjh.14623] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Sami Al-Battat
- Division of Haematology/Oncology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.,Department of Paediatrics, University of Toronto, Toronto, ON, Canada
| | - Margaret L Rand
- Division of Haematology/Oncology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.,Department of Paediatrics, University of Toronto, Toronto, ON, Canada.,Departments of Laboratory Medicine & Pathobiology, Biochemistry and Paediatrics, University of Toronto, Toronto, ON, Canada.,Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Vanessa Bouskill
- Department of Nursing, The Hospital for Sick Children, Toronto, ON, Canada
| | - Wendy Lau
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, ON, Canada
| | - Victor S Blanchette
- Division of Haematology/Oncology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.,Department of Paediatrics, University of Toronto, Toronto, ON, Canada
| | - Walter H A Kahr
- Division of Haematology/Oncology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.,Department of Paediatrics, University of Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Cell Biology Program, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Georges-Etienne Rivard
- Division of Haematology/Oncology, Department of Paediatrics, CHU Sainte-Justine, Montreal, QC, Canada
| | - Manuel D Carcao
- Division of Haematology/Oncology, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.,Department of Paediatrics, University of Toronto, Toronto, ON, Canada.,Child Health Evaluative Sciences, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
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16
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Nijdam A, Altisent C, Carcao MD, Cid AR, Claeyssens-Donadel S, Kurnik K, Ljung R, Nolan B, Petrini P, Platokouki H, Rafowicz A, Thomas AE, Fischer K. Bleeding before prophylaxis in severe hemophilia: paradigm shift over two decades. Haematologica 2014; 100:e84-6. [PMID: 25527565 DOI: 10.3324/haematol.2014.115709] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Affiliation(s)
- Annelies Nijdam
- Van Creveldkliniek, Center for Benign Hematology, Thrombosis and Hemostasis, University Medical Center Utrecht, Netherlands
| | | | - Manuel D Carcao
- Division of Haematology/Oncology, Department of Paediatrics and Child Health Evaluative Sciences, Research Institute, The Hospital for Sick Children, Toronto, ON, Canada
| | - Ana R Cid
- Unidad de Hemostasia y Trombosis, Hospital Universitario la Fe, Valencia, Spain
| | | | - Karin Kurnik
- Dr. von Haunersches Children's Hospital, University of Munich, Germany
| | - Rolf Ljung
- Lund University, Department of Clinical Sciences Lund -Paediatrics and Malmö Haemostasis & Thrombosis Centre, Skåne University Hospital, Malmö, Sweden
| | - Beatrice Nolan
- Department of Haematology Oncology, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland
| | - Pia Petrini
- Paediatric Department of Coagulation Disorders, Karolinska University Hospital, Stockholm, Sweden
| | - Helen Platokouki
- St. Sophia Children's Hospital, Haemophilia-Haemostasis Unit, Athens, Greece
| | - Anne Rafowicz
- Centre Régional de Traitement de l'Hémophilie et Autres Maladies Hémorragiques, Centre Hospitalier Universitaire de Bicêtre, Paris, France
| | - Angela E Thomas
- Department of Haematology, Royal Hospital for Sick Children, Edinburgh, Scotland
| | - Kathelijn Fischer
- Van Creveldkliniek, Center for Benign Hematology, Thrombosis and Hemostasis, University Medical Center Utrecht, Netherlands Julius Center for Health Sciences and Primary Care, University Medical Center, Utrecht, The Netherlands
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17
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Labarque V, Stain AM, Blanchette V, Kahr WHA, Carcao MD. Intracranial haemorrhage in von Willebrand disease: a report on six cases. Haemophilia 2013; 19:602-6. [PMID: 23556472 DOI: 10.1111/hae.12142] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2013] [Indexed: 11/29/2022]
Abstract
The incidence of intracranial haemorrhage (ICH) in von Willebrand disease (VWD) is not well documented. We describe our single centre experience regarding ICH in children with VWD and identify how such children presented and were managed. Thirty-three head trauma events leading to medical attention occurred in 24 of 153 children with VWD followed in our institution. In only 15 of these were computed tomography (CT) imaging studies performed; seven in children with type 1 VWD, one in a child with type 2N VWD and seven in children with type 3 VWD. In six of these 15 episodes an ICH was identified: two children with type 1 VWD, one child with type 2N VWD and three children with type 3 VWD. In two of the 6 cases an ICH was only confirmed following a second CT scan. Neurological symptoms, including vomiting (noted in all six), headache, irritability, lethargy and/or alteration in the level of consciousness were present in all children with confirmed ICH. In contrast vomiting, irritability and alterations in level of consciousness were never present in those children without confirmed ICH. All three children with type 3 VWD who experienced an ICH were commenced on long-term prophylaxis. ICH, although rare, does occur in children with VWD and particularly in children with type 3 VWD. A much larger cohort of patients with VWD experiencing an ICH is needed to make recommendations regarding treatment of such events, including the role of prophylaxis in patients with more severe forms of VWD.
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Affiliation(s)
- V Labarque
- Division of Haematology/Oncology, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
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18
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Abshire TC, Federici AB, Alvárez MT, Bowen J, Carcao MD, Cox Gill J, Key NS, Kouides PA, Kurnik K, Lail AE, Leebeek FWG, Makris M, Mannucci PM, Winikoff R, Berntorp E. Prophylaxis in severe forms of von Willebrand's disease: results from the von Willebrand Disease Prophylaxis Network (VWD PN). Haemophilia 2012; 19:76-81. [PMID: 22823000 DOI: 10.1111/j.1365-2516.2012.02916.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2012] [Indexed: 11/27/2022]
Abstract
The bleeding patterns of severe von Willebrand's disease (VWD) adversely affect quality of life, and may be life threatening. There is a presumed role for prophylaxis with VWF-containing concentrates, but data are scarce. The von Willebrand Disease Prophylaxis Network (VWD PN) was formed to investigate the role of prophylaxis in clinically severe VWD that is not responsive to other treatment(s).Using a retrospective design, the effect of prophylaxis was studied. Availability of records to document, or reliably assess, the type and frequency of bleeding episodes prior to, and after, the initiation of prophylaxis was required. Annualized bleeding rates were calculated for the period prior to prophylaxis, during prophylaxis and by primary bleeding indication defined as the site accounting for more than half of all bleeding symptoms. The Wilcoxon signed-rank test of differences in the medians was used. Sixty-one subjects from 20 centres in 10 countries were enrolled. Data for 59 were used in the analysis. The median age at onset of prophylaxis was 22.4 years. Type 3 VWD accounted for the largest number (N = 34, 57.6%). Differences in bleeding rates within individuals during compared with before prophylaxis were significant for the total group (P < 0.0001), and for those with primary bleeding indications of epistaxis (P = 0.0005), joint bleeding (P = 0.002) and GI bleeding (P = 0.001). The effect of prophylaxis was similar among those age < 18 years and those ≥ 18. One person developed an inhibitor during treatment. We conclude that prophylactic treatment of VWD is efficacious.
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Affiliation(s)
- T C Abshire
- Medical Sciences Institute, BloodCenter of Wisconsin, Milwaukee, WI, USA
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19
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Gupta M, Lillicrap D, Stain AM, Friedman KD, Carcao MD. Therapeutic consequences for misdiagnosis of type 2N von Willebrand disease. Pediatr Blood Cancer 2011; 57:1081-3. [PMID: 21425451 DOI: 10.1002/pbc.23120] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 02/14/2011] [Indexed: 11/06/2022]
Abstract
Patients presenting with a low FVIII:C and with normal VWF levels are usually presumed to have hemophilia (males) or be carriers for hemophilia (females). Some of these patients may instead have VWD:2N. Such patients if misdiagnosed are likely to suffer from insufficiently treated bleeds. We report 2 males and 1 female who presented with a low FVIII:C (1-21%) and minimally reduced/normal VWF and were assumed to have, or be a carrier for, hemophilia A. Eventually all were found to have VWD:2N. Prior to the correct diagnosis the males had been treated with rFVIII with poor responses and ultimately adverse clinical consequences.
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Affiliation(s)
- Madhu Gupta
- Division of Hematology/Oncology, Hospital for Sick Children, Toronto, Ontario, Canada
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20
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Robertson JD, Yenson PR, Rand ML, Blanchette VS, Carcao MD, Notley C, Lillicrap D, James PD. Expanded phenotype-genotype correlations in a pediatric population with type 1 von Willebrand disease. J Thromb Haemost 2011; 9:1752-60. [PMID: 21711445 DOI: 10.1111/j.1538-7836.2011.04423.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Recent phenotype-genotype studies have provided valuable insights into the pathophysiology of type 1 von Willebrand disease (VWD); however, no study has examined an exclusively pediatric cohort. OBJECTIVES To describe phenotype-genotype correlations in a selected pediatric cohort with a historical diagnosis of type 1 VWD, using first-degree family members as controls. METHODS Comprehensive phenotypic assessment included standard assays of von Willebrand factor (VWF) level and function, bleeding score, desmopressin response, VWF propeptide (VWFpp) level, and platelet-derived VWF mRNA level. RESULTS Fourteen VWF mutations were identified in 17 of 23 index cases (ICs) (aged 5-17 years), including four that were previously unreported (L60P, nt1658 insT, Q1388X, and C2237F). VWFpp levels were lower in ICs than in unaffected controls (median 49 vs. 86 U dL(-1) , P < 0.0001). A VWFpp/VWF antigen ratio of > 1.6 was observed in eight of nine ICs with a suboptimal response to desmopressin, including four of four with the R1205H (Vicenza) mutation (median 7.9), and three of four IC with the R1315C mutation (median 1.9). The R1315C mutation was also associated with a reduced absolute VWFpp level (median 32 U dL(-1) ), a previously unreported finding. The amount of platelet-derived VWF mRNA was significantly reduced in individuals with nonsense mutations. CONCLUSIONS Increased VWF clearance and intracellular retention are important mechanisms underlying type 1 VWD in pediatric patients, concordant with the observations of larger, predominantly adult, cohort studies. Additionally, in some patients, nonsense-mediated decay of mutant mRNA transcripts may be contributory. Several mechanisms underlie the variable phenotype associated with the R1315C mutation. The potential utility of VWFpp as an independent marker of VWF biosynthesis and release warrants further research.
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Affiliation(s)
- J D Robertson
- Haematology Service, Division of Oncology, Royal Children's Hospital Department of Haematology, Pathology Queensland, Brisbane, QLD, Australia.
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21
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Seary ME, Feldman D, Carcao MD. DDAVP responsiveness in children with mild or moderate haemophilia A correlates with age, endogenous FVIII:C level and with haemophilic genotype. Haemophilia 2011; 18:50-5. [PMID: 21592259 DOI: 10.1111/j.1365-2516.2011.02572.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In most individuals with moderate/mild haemophilia A, FVIII:C levels increase following DDAVP administration to a haemostatic range, thus avoiding the need for FVIII concentrates. We sought to determine the relationship between responsiveness to DDAVP in boys (<18 years old) with mild/moderate haemophilia and patient age, haemophilic severity and haemophilic genotype. Our cohort consisted of 13 boys with moderate and 61 boys with mild haemophilia who, between them, had 38 different mutations; 21 had unique mutations not shared by any other clinic patient, whereas 53 shared one of 17 mutations with some other clinic patient (included 26 boys with ≥ 1 haemophilic brother). Patient age and endogenous FVIII:C levels were strong predictors of response to DDAVP. Younger patients responded less well to DDAVP and 10 of the 11 patients, when retested at an older age, showed an improved response to DDAVP. Only 1 patient with moderate haemophilia responded to DDAVP, whereas 80% of patients with mild haemophilia responded (including all patients with an endogenous FVIII:C of >0.15 U mL(-1)). Almost all patients with the same mutation had the same response to DDAVP or only a minor discordance in response. Patient's age, disease severity and genotype all are predictors of response to DDAVP.
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Affiliation(s)
- M E Seary
- Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
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22
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Abstract
Type 3 Von Willebrand disease (VWD) is a rare, severe, autosomal recessive bleeding disorder. In our institution, we follow 17 children with type 3 VWD. We have observed a high prevalence of dental disease in these patients prompting us to undertake a retrospective review of our cohort of patients with type 3 VWD to catalogue the extent of their dental disease. Sixteen of these patients have been assessed by our dentistry department. Five children have undergone minor dental procedures (e.g. restorations, stainless steel crowns) and seven major procedures (e.g. dental extractions, pulpotomies and root canal treatments). These patients have collectively used 85,400 (ristocetin cofactor) IU of Humate-P on dental procedures alone. In addition to the considerable costs of factor are the cost of operating room time, dentists' costs, and the cost of other topical haemostatic agents (e.g. Tisseel) used during their dental procedures. As such there is considerable morbidity and cost from dental disease in these patients that is much higher than what is seen in patients with haemophilia or in the normal paediatric population. We speculate that the combination of these patients having a significant mucosal bleeding disorder together with various socioeconomic factors contribute to the significant degree of dental disease seen in this group of patients. We would suggest that better preventive dental care needs to be provided to these patients to avoid the considerable morbidity and very high burden of dental disease in type 3 VWD.
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Affiliation(s)
- M D Carcao
- Child Health Evaluative Sciences, Research Institute, Department of Pediatrics, The Hospital for Sick Children, Toronto, ON, Canada.
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23
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Abstract
Immune tolerance therapy (ITT) is the most effective approach to eradicate inhibitors in patients with haemophilia who develop high-titre inhibitors. Yet ITT is associated with many adverse side-effects. Rarely, adverse side-effects arise from the various factor concentrates that patients on ITT receive or from adjuvant immunosuppressive agents used during ITT. Most adverse side-effects of ITT are related to the need for frequent and repetitive venous access, which often results in the need for central venous access devices (CVAD). These devices greatly facilitate the ability to give repeated doses of factor concentrates to patients and are particularly useful in young children who often have small and poorly functioning peripheral veins. These devices can become infected, can malfunction or can lead to venous thrombosis. These complications, although rarely causing mortality, may lead to significant morbidity including the need to have the devices removed and new ones inserted. As well, such CVAD complications may lead to reduced effectiveness of ITT through interruptions in ITT.
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Affiliation(s)
- Manuel D Carcao
- Department of Paediatrics, Division of Haematology/Oncology Child Health Evaluative Sciences, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
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Abstract
Recombinant activated factor VII (rFVIIa; NovoSeven, NiaStase, Novo Nordisk, Bagsvaerd, Denmark) was originally developed for the treatment of bleeds in patients with hemophilia and inhibitors. However, the agent is increasingly being employed in "off-label"/unlicensed indications. Consequently there is a need to undertake comprehensive reviews of rFVIIa use; the resulting information will facilitate understanding of how the agent is currently being employed and help to determine trends in its use. This article considers two recently reported reviews describing the use of rFVIIa in two heavily populated regions of Canada--regions with a combined population capture area of approximately 8.5 million people. The reviews report rFVIIa use in a total of 196 patients who collectively received 15,262.8 mg of rFVIIa. Both reviews obtained similar findings and reached similar conclusions: the majority of patients receiving rFVIIa are being treated for "off-label" indications, with numbers of such patients having grown rapidly between the years 2000 and 2005. However, hemophilia patients still account for the vast majority of rFVIIa use, as small numbers of hemophilia patients can consume large quantities of the agent. It is important to be aware of the increasing use of rFVIIa in off-label indications.
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Affiliation(s)
- Manuel D Carcao
- Division of Hematology/Oncology, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Canada.
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25
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Traivaree C, Blanchette V, Armstrong D, Floros G, Stain AM, Carcao MD. Intracranial bleeding in haemophilia beyond the neonatal period ? the role of CT imaging in suspected intracranial bleeding. Haemophilia 2007; 13:552-9. [PMID: 17880443 DOI: 10.1111/j.1365-2516.2007.01545.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We conducted a review of a single institutional experience of patients with haemophilia presenting with suspected intracranial haemorrhage (ICH) who underwent computed tomographic (CT) neuro-imaging. We found that over a 9-year period (1996-2004) 43 patients with haemophilia presented 73 times with suspected ICH: 10 presented multiple times (range: 2-9 times). The median age at presentation was 3.5 years (range: 0.5-17). Preceding trauma occurred in most (62/73; 85%) episodes. ICH was confirmed in 11 of the 73 (16%) episodes in eight patients. Patients with severe haemophilia accounted for a disproportionate number of episodes of suspected (60/73; 82%) and of confirmed ICH (10/11; 91%). All ICH occurred in patients not on prophylaxis; five occurred in three inhibitor-positive patients. Altered consciousness at presentation was present in 10/11 (91%) cases of confirmed ICH but only in 5/62 (8%) (ICH-negative) episodes. The positive and negative predictive values of altered consciousness to predict/rule out an ICH was 67% and 98%, respectively. The following were associated with an increased risk of presenting with suspected ICH and of having a confirmed ICH: (i) having severe haemophilia; (ii) not being on prophylaxis; (iii) having an inhibitor; and (iv) presenting with an altered level of consciousness. Patients without any of these features may not need to undergo CT imaging when presenting with suspected ICH. Ideally a prospective study to evaluate this hypothesis should be conducted.
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Affiliation(s)
- C Traivaree
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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26
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Affiliation(s)
- M D Carcao
- Division of Haematology/Oncology, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, Canada.
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27
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Ota S, Mclimont M, Carcao MD, Blanchette VS, Graham N, Paradis E, Feldman BM. Definitions for haemophilia prophylaxis and its outcomes: The Canadian Consensus Study. Haemophilia 2007; 13:12-20. [PMID: 17212719 DOI: 10.1111/j.1365-2516.2006.01409.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The creation of acceptable standard definitions for terms used in the care and assessment of haemophilia patients has become increasingly important, as a growing number of international clinical studies have been initiated. The Delphi approach has been used in health research to reach consensus in large groups and can be used to develop definitions by using several iterations of surveys eliciting opinions from specialists in the field. Three consecutive surveys were designed based on the Delphi approach and distributed to specialist physicians, nurses and physiotherapists in order to develop definitions for seven haemophilia terms: 'primary prophylaxis', 'secondary prophylaxis', 'target joint', 'joint bleed', 'significant soft-tissue bleed', 'superficial soft-tissue bleed' and 'mucosal bleed'. Suggestions were solicited, compiled into a subsequent survey and fed back to the group to rank-order the importance of each suggested component of the definition. Final definitions were created using the top-ranked suggestions and sent back to the experts for approval. Five of the seven terms were highly endorsed with greater than 90% agreement. Some differences in agreement were found when analysed by profession. Haemophilia terms were successfully defined using the Delphi approach. Further refinement from members of the international haemophilia community will ensure that comprehensive standard definitions can be used in multicentre studies in the future.
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Affiliation(s)
- S Ota
- Research program in Child Health Evaluation Sicenses, The Hospital for Sick Children, Toronto, Canada
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28
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Abstract
Severe congenital neutropenia (SCN) and Clostridium septicum myonecrosis is an uncommon and life-threatening association requiring urgent combined aggressive medical and surgical management. We report 2 cases of SCN (1 with known Kostmann's syndrome and 1 not known at presentation to have a congenital neutropenic disorder but subsequently received a diagnosis of cyclic neutropenia) who presented with spontaneous C septicum myonecrosis. The cases highlight the importance of response to recombinant human granulocyte colony-stimulating factor in obtaining a satisfactory outcome for these patients. Early, empirical use of recombinant human granulocyte colony-stimulating factor in patients who are suspected of having a congenital neutropenia and who present with life-threatening sepsis is recommended.
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Affiliation(s)
- Chris Barnes
- Division of Haematology/Oncology, Department of Paediatrics, Hospital for Sick Children, Toronto, Ontario, Canada
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29
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Abstract
Prophylaxis, the regular infusion of coagulation factor concentrates to severe hemophiliacs, has been an evolving therapeutic tool of management for the past three decades. Multiple clinical trials have and continue to be conducted in the field of prophylaxis in an attempt to determine ideal regimens of prophylaxis, its benefits, its risks and costs, and to address still unanswered questions; who to place on prophylaxis, when to start prophylaxis, when (if ever) to stop prophylaxis, etc. We present a detailed review and discussion of the evolution of prophylaxis as a tool in managing patients with hemophilia and we address the major issues and still unanswered questions.
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Affiliation(s)
- Manuel D Carcao
- Department of Paediatrics, Division of Haematology/Oncology, Hospital for Sick Children, University of Toronto, Toronto, Canada
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30
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Abstract
PURPOSE To determine the pattern and predictors of response to desmopressin (DDAVP) in children with von Willebrand disease (VWD). METHODS The authors reviewed the hospital records of all children with type 1 (n = 70) and type 2A (n = 5) VWD who were followed in the institution's Bleeding Disorders Clinic from January 1989 to June 2001 and who had a DDAVP challenge test after diagnosis. The major outcome evaluated was response to DDAVP, defined as an increase of greater than twofold over baseline of von Willebrand factor, ristocetin cofactor (VWF:RCo), and factor VIII coagulant (FVIII:C) and levels above 0.3 IU/mL. RESULTS Response to DDAVP was observed in 56 (80%) of the 70 children with type 1 VWD. Age and baseline VWF:RCo and FVIII:C levels were positively associated with DDAVP response. A total of 36 children (28 responders, 8 nonresponders) with type 1 VWD were treated for bleeding episodes or for prophylaxis; of these 75% (6/8) of the nonresponders compared with 7% (2/28) of the responders to a DDAVP challenge test received blood component therapy (P < 0.01). One of the five children with type 2A VWD responded to DDAVP. CONCLUSIONS DDAVP challenge tests are recommended in children with newly diagnosed VWD to identify responders in whom DDAVP may be used for the prevention or treatment of bleeding, thus avoiding exposure to blood products. The association of DDAVP response with age merits further investigation.
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Affiliation(s)
- Shoshana Revel-Vilk
- Division of Hematology/Oncology, The Hospital for Sick Children, University of Toronto, Ontario, Canada
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31
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Carcao MD, Connolly BL, Chait P, Stain AM, Acebes M, Massicotte P, Blanchette VS. Central venous catheter-related thrombosis presenting as superior vena cava syndrome in a haemophilic patient with inhibitors. Haemophilia 2003; 9:578-83. [PMID: 14511297 DOI: 10.1046/j.1365-2516.2003.00791.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We report the case of a 10.5-year-old boy with severe haemophilia A (SHA) and inhibitors who presented with superior vena cava (SVC) obstruction while on immune tolerance induction (ITI) with daily recombinant factor VIII (rFVIII) and factor eight bypassing activity (FEIBA) (75 U kg(-1)) twice a week. The boy had a right-sided implanted central venous catheter. Imaging revealed a large occlusive thrombus in the SVC with all upper venous system drainage occurring through the azygos and collateral veins. Despite initial success with local thrombolytic therapy using recombinant tissue plasminogen activator, the thrombus persisted. Mechanical thrombolysis and angioplasty resulted in the successful removal of the thrombus and resolution of the SVC syndrome. Unfractionated heparin was used to prevent thrombus reformation/propagation. A work-up did not reveal any underlying genetic prothrombotic risk factors. The occurrence of such a profoundly symptomatic thromboembolism (TE) in a boy with SHA with inhibitors is unusual. A combination of risk factors, including the ongoing infusion of high doses of FVIII in the context of a disappearance of inhibitors together with the infusion of clotting factors known to be potentially thrombogenic, may place haemophilic patients on ITI (immune tolerance induction) at risk for this rare, life-threatening complication. The appropriate management of TEs in such a setting is unknown.
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Affiliation(s)
- M D Carcao
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Canada.
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32
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Sharathkumar A, Lillicrap D, Blanchette VS, Kern M, Leggo J, Stain AM, Brooker L, Carcao MD. Intensive exposure to factor VIII is a risk factor for inhibitor development in mild hemophilia A. J Thromb Haemost 2003; 1:1228-36. [PMID: 12871324 DOI: 10.1046/j.1538-7836.2003.00230.x] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Inhibitors are rare in boys with mild hemophilia A (MHA; factor (F)VIII:C > 5%) but may arise following intense FVIII exposure, e.g. continuous infusion (CI). OBJECTIVES To determine the impact of intense FVIII exposure in inhibitor formation in MHA at our institution and to compare this with previous reports. PATIENTS AND METHODS We reviewed FVIII exposure and inhibitor development in boys (ages 0-18 years) with MHA followed at our institution from 1996 to 2001 and conducted a Medline search (1966-2002) on the experience of inhibitor development following intensive/CI exposure to FVIII. RESULTS We identified 54 boys with MHA. Twenty-nine (54%) had been exposed to FVIII. Seven had received FVIII by CI. Four developed inhibitors; three high titer (at ages 10 years, 16 years and 17 years) and one low titer (at 1 month old). All four had received a CI of recombinant (r) FVIII of at least 6 days within 6 weeks of developing inhibitors. Baseline FVIII levels fell to < 1% in all cases and the three with high-titer inhibitors developed severe bleeding. Immune tolerance therapy (ITT) was attempted in two boys and was successful in one. Our literature search identified 35 cases (only four children) with MHA developing inhibitors following intense FVIII exposure often in the context of surgery. CONCLUSIONS The incidence of inhibitors in our MHA population was 7.4%. If expressed according to exposure the incidence was significantly higher: 14% (4/29) for any exposure to FVIII and 57% (4/7) for exposure by CI. A prospective study to address whether CI is associated with an increased incidence of inhibitor development in MHA is warranted.
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Affiliation(s)
- A Sharathkumar
- Division of Haematology/Oncology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada M5G 1X8
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33
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Carcao MD, Blanchette VS, Wakefield CD, Stephens D, Ellis J, Matheson K, Denomme GA. Fcgamma receptor IIa and IIIa polymorphisms in childhood immune thrombocytopenic purpura. Br J Haematol 2003; 120:135-41. [PMID: 12492589 DOI: 10.1046/j.1365-2141.2003.04033.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fcgamma receptor-mediated destruction of autoantibody-sensitized platelets is central to the immune pathophysiology of childhood immune thrombocytopenic purpura (ITP). Allelic variants exist among the random population for some Fcgamma receptors. The variants represent single nucleotide polymorphisms, leading to functional differences in the ability to bind immunoglobulin (Ig)G or IgG subclasses. The genotypic frequencies for two Fcgamma receptor single nucleotide polymorphisms, FcgammaRIIa-131 arginine (R) versus histidine (H) and FcgammaRIIIa-158 valine (V) versus phenylalanine (F) were examined in 98 children diagnosed with childhood ITP. The genotype frequencies were compared with those of 130 healthy control subjects. Chi-square analysis was used to determine whether the allelic frequencies of the high-affinity receptor variants were associated with childhood ITP. Both the FcgammaRIIa-131H and the FcgammaRIIIa-158V were significantly over-represented in children with ITP versus the control subjects (P-values 0.03). The same statistical difference was noted with the combined FcgammaRIIa-131H and FcgammaRIIIa-158V allelic gene frequencies. There was no statistical difference between children who later developed chronic ITP compared with children with acute ITP, suggesting that additional factors are responsible for the development of the chronic form of the disease. These observations underscore the importance of Fcgamma receptor-mediated cell clearance in childhood ITP.
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Affiliation(s)
- Manuel D Carcao
- Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, Canada
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34
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Abstract
Desmopressin (DDAVP) increases plasma factor VIII coagulant activity (FVIII:C) levels in patients with mild/moderate haemophilia A. In some subjects, FVIII can be increased to haemostatic levels, thereby avoiding use of factor VIII concentrates. We reviewed our hospital's experience with 62 boys with FVIII:C levels 0.01-0.3 IU/ml who had a DDAVP challenge test (i.v. 0.3 microg/kg) following diagnosis. A therapeutic response was defined as a 1 h post-FVIII:C increase at least twofold over baseline and > 0.3 IU/ml. Of the total group, 29 (47%) boys responded to DDAVP, all of them with mild haemophilia (baseline FVIII:C > or = 0.05 IU/ml), yielding a response rate of 57% in this subgroup. Boys who responded to DDAVP had higher baseline FVIII:C levels (mean +/- SEM, 0.17 +/- 0.01 vs 0.10 +/- 0.01 IU/ml, P < 0.01) and were older (5.2 +/- 0.8 vs 3 +/- 0.4 years, P = 0.02) than those who failed to do so. The association between DDAVP response and age, however, remains unclear: seven boys who failed the initial challenge test responded to re-challenge after a mean of 6.3 years (median 4.9, range 0.5-12.5), increasing the response rate in boys with mild haemophilia to 71%. Age and FVIII:C association with DDAVP response are both important in boys with mild/moderate haemophilia A. Absence of response to DDAVP should therefore be confirmed by later re-challenge.
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Affiliation(s)
- Shoshana Revel-Vilk
- Department of Paediatrics, The Hospital for Sick Children and the University of Toronto, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada
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35
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Carcao MD, Blanchette VS, Stephens D, He L, Wakefield CD, Butchart S, Christie DJ, Rand ML. Assessment of thrombocytopenic disorders using the Platelet Function Analyzer (PFA-100). Br J Haematol 2002; 117:961-4. [PMID: 12060138 DOI: 10.1046/j.1365-2141.2002.03511.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Platelet Function Analyzer (PFA-100) was used to measure platelet function in paediatric patients with destructive versus underproduction thrombocytopenia. Closure time (CT) and total volume (TV) measurements with standard 150 microm apertures discriminated between patients with similar platelet counts from 30 to 150 x 10(9)/l. However, at platelet counts < 30 x 10(9)/l, a 100-microm aperture (experimental) gave the best assessment of platelet function. TV results could be analysed even when CTs were indeterminate. Further investigations are warranted to more fully understand the relationships among platelet function as measured by the PFA-100 in standard/experimental modes, bleeding and transfusion outcome in thrombocytopenia.
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Affiliation(s)
- Manuel D Carcao
- Divisions of Haematology/Oncology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada
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36
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Waye JS, Eng B, Patterson M, Carcao MD, Chang L, Olivieri NF, Chui DH. Identification of two new alpha-thalassemia mutations in exon 2 of the alpha1-globin gene. Hemoglobin 2001; 25:391-6. [PMID: 11791872 DOI: 10.1081/hem-100107876] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The most common causes of alpha-thalassemia are deletions that remove one or both of the functional alpha-globin genes. In addition, more than 30 different point mutations and small deletions/insertions have been reported for the alpha-globin genes. Here, we describe two new mutations occurring in exon 2 of the alpha1-globin gene. One mutation is an insertion of 21 bp that gives rise to a predicted alpha-globin chain containing a duplication of amino acid residues 93-99. The second mutation is a 33 bp deletion resulting in a predicted alpha-globin chain that is missing amino acid residues 64-74. Neither mutation results in a detectable hemoglobin variant, indicating that the variant alpha-globin chains are highly unstable. Carriers of these mutations have mild microcytosis and the phenotype of alpha+-thalassemia trait.
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Affiliation(s)
- J S Waye
- Provincial Hemoglobinopathy and DNA Diagnostic Laboratory, Hamilton Regional Laboratory Medicine Program, Ontario, Canada.
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Waye JS, Eng B, Patterson M, Walker L, Carcao MD, Olivieri NF, Chui DH. Hemoglobin H (Hb H) disease in Canada: molecular diagnosis and review of 116 cases. Am J Hematol 2001; 68:11-5. [PMID: 11559931 DOI: 10.1002/ajh.1142] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Over the past decade, we have characterized at the DNA level a total of 116 hemoglobin H (Hb H) disease patients living in Canada. The majority of patients were of southeast Asian descent (Chinese, Filipino, Laotian, Vietnamese), with a small number being of Mediterranean, Middle Eastern or East Indian background. A total of 15 distinct genotypes were detected, all but one being compound heterozygotes for a two-gene cis deletion and a single-gene deletion (-alpha/-) or a non-deletion mutation of the alpha2-globin gene (alpha(T) alpha/-). Seven different two-gene cis deletions were encountered, along with nine single-gene deletions and point mutations. The wide range of mutations associated with Hb H disease in Canada is a reflection of the population heterogeneity. The diagnosis of Hb H disease at the molecular level is important with respect to genetic counseling and the identification of families at risk for having pregnancies affected with Hb Bart's hydrops fetalis syndrome and/or Hb H disease. Six of the Hb H disease patients in our cohort had spouses who carried single-gene deletions, making these couples at risk for having children with Hb H disease. More important, seven patients had partners who carried two-gene cis deletions. These couples are at reproductive risk for both Hb Bart's hydrops fetalis syndrome and Hb H disease.
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Affiliation(s)
- J S Waye
- Provincial Hemoglobinopathy DNA Diagnostic Laboratory, Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada.
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38
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Dean JA, Blanchette VS, Carcao MD, Stain AM, Sparling CR, Siekmann J, Turecek PL, Lillicrap D, Rand ML. von Willebrand disease in a pediatric-based population--comparison of type 1 diagnostic criteria and use of the PFA-100 and a von Willebrand factor/collagen-binding assay. Thromb Haemost 2000; 84:401-9. [PMID: 11019962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Definitive diagnosis of type 1 von Willebrand Disease (VWD) remains a problem. Provisional consensus guidelines for the diagnosis of definite and possible type 1 VWD were prepared by the Scientific Subcommittee on von Willebrand factor (VWF) of the Scientific and Standardization Committee (SSC) of the International Society on Thrombosis and Haemostasis (ISTH) during the 1996 annual meeting for the specific purpose of further evaluation in retrospective and prospective studies by a Working Party on Diagnostic Criteria (1996 Annual Report of the SSC/ISTH Subcommittee on VWF). In the first phase of this study, we compared 2 definitions of type 1 VWD. each with 3 criteria: significant bleeding history, laboratory investigations, and family history. Using the ISTH consensus guidelines for type 1 VWD definition, significantly fewer patients were diagnosed with definite type 1 disease as compared to our "in house" Hospital for Sick Children (HSC) criteria (4 vs. 31). While we recognize that the provisional ISTH consensus guidelines were not intended for clinical use, we believe that the results of our studies are of interest and will assist in any future refinements to the ISTH guidelines. In the second phase of this study, we investigated the utility of 2 new tests, a laboratory screening test and a functional test, for VWD in our well characterized, pediatric-based population. The Platelet Function Analyzer (PFA-100) provides an in vitro measure of primary hemostasis under conditions of high shear, using disposable cartridges containing collagen and either epinephrine or ADP. All tested subjects with types 2 or 3 VWD had prolonged PFA-100 closure times (CTs) with both cartridge types (n = 17) and prolonged bleeding times (n = 14). In subjects with definite type 1 VWD, 20/24 (83%) had prolonged CTs with the collagen/ADP cartridge (19/24 (79%) with collagen/epinephrine), compared with 7/26 (27%) with prolonged bleeding times. In subjects with definite types 1, 2, or 3 VWD, collagen/ADP CTs were abnormal in 37/41 subjects, giving an overall sensitivity of 90%. With this high sensitivity, the PFA-100 is a better screening test for VWD than the bleeding time. We also tested a VWF collagen-binding assay (VWF:CBA) as a functional test for VWF, in comparison with the more routinely-used ristocetin cofactor assay (VWF:RC0). The VWF:CBA is based on an ELISA technique, which has the potential to be more reproducible than the VWF:RC0. We found that the VWF:CBA detected 43/49 (88%) subjects with definite types 1, 2, or 3 VWD, performing as well as the VWF:RC0, that detected 42/48 (88%). We also showed that, used in conjunction with VWF antigen levels, the VWF:CBA may be useful in classification of VWD subtypes.
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Affiliation(s)
- J A Dean
- Department of Paediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
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39
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Affiliation(s)
- M D Carcao
- The Hospital for Sick Children, Toronto, Ontario, Canada
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40
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Abstract
The platelet function analyzer, PFA-100, has been designed to provide an in vitro measure of primary hemostasis simply, quickly, quantitatively, and accurately to aid in the routine screening of patients with potential hemorrhagic risk due to abnormal platelet plug formation. The system measures the closure time (CT), or the time taken for platelets in a sample of anticoagulated blood to form a plug that occludes a microscopic aperture cut into a membrane coated with collagen and either epinephrine or ADP. The high shear stresses produced in the analyzer lead to platelet plug formation that is greatly dependent on von Willebrand's factor (vWF). In this article, we detail the system itself and describe our initial studies using the PFA-100 to assess primary hemostasis in pediatric populations. Normal ranges have been established for healthy children and neonates. CTs for healthy children are independent of the needle gauge (21G or 23G) used for blood sampling. They are similar to CTs for healthy adults, but neonates have significantly shorter CTs, likely due to increased levels of vWF. Children with hemophilia have normal CTs, whereas seven out of eight patients with von Willebrand's disease (vWD) have abnormally long CTs. CT reproducibility between duplicate samples is excellent. Our preliminary results indicate that the PFA-100 will be useful in the evaluation of primary hemostasis in children, as well as in adults.
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Affiliation(s)
- M L Rand
- The Hospital for Sick Children, Department of Biochemistry, University of Toronto, Ontario, Canada
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41
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Carcao MD, Taylor GP, Greenberg ML, Bernstein ML, Champagne M, Hershon L, Baruchel S. Renal-cell carcinoma in children: a different disorder from its adult counterpart? Med Pediatr Oncol 1998; 31:153-8. [PMID: 9722897 DOI: 10.1002/(sici)1096-911x(199809)31:3<153::aid-mpo5>3.0.co;2-a] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Renal-cell carcinoma (RCC) is a rare tumor in children. To address whether RCC in children differs from its adult counterpart, we report a series of 16 children with RCC (5 boys, 11 girls, mean age 9.6 years, range 3-19 years) presenting between 1979 and 1996 at three pediatric centers. PROCEDURE Pathology showed papillary RCC in five patients (31%). Nonpapillary tumors were present in 11 (69%), of which nine were clear-cell type (56%), one was chromophobe-cell type (6%), and one was granular-cell type (6%). Cytogenetic studies were performed on four. RESULTS In two tumors, normal karyotypes (45,XX or 45,XY) were found. In another, there were translocations: t(X;1), t(X;2) and t(6;14). In the fourth, analysis revealed 46,XX/46,X,t(X;17)(p11.2;q25),t(1;12). Several features in this series differ from those reported in adults. In adults, RCC is more frequent in males, is usually nonpapillary, and is characterized cytogenetically by deletions or rearrangements in the short arm of chromosome 3. In contrast, in our series there was no male predominance and a higher proportion of papillary tumors. In addition, two of four cytogenetically analyzed tumors had translocations involving the X chromosome. Translocations involving the Xp11.2 locus have been infrequently reported in both adults and children with papillary RCC. CONCLUSIONS The higher frequency of papillary histology and the presence of translocations involving Xp.11.2 in two cases raise the possibility of a unique subtype of RCC in children.
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Affiliation(s)
- M D Carcao
- Department of Paediatrics, Hospital for Sick Children, Toronto, Ontario, Canada
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Carcao MD, Lau RC, Gupta A, Huerter H, Koren G, King SM. Sequential use of intravenous and oral acyclovir in the therapy of varicella in immunocompromised children. Pediatr Infect Dis J 1998; 17:626-31. [PMID: 9686730 DOI: 10.1097/00006454-199807000-00010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Immunocompromised children are at risk for disseminated varicella infections. Standard management involves hospitalization and intravenous acyclovir for 7 to 10 days. This approach is expensive, is inconvenient and may not be necessary. We undertook a pilot study to assess the safety and efficacy of an alternative approach that utilized a combination of intravenous (i.v.) followed by oral (p.o) acyclovir in a cohort of immunocompromised children. METHODS The cohort consisted of 26 immunocompromised children between the ages of 1.5 and 12.7 years (mean, 6.3). Therapy was commenced with i.v. acyclovir (1500 mg/m2/day in 3 divided doses). Concurrent management included holding or reducing immunosuppressive therapy (by 50%) and administering varicella-zoster immunoglobulin in 69% (11 of 16) of cases where exposure to chickenpox was recognized. Patients were eligible to switch to p.o therapy after receiving a minimum of 48 h of i.v. acyclovir therapy provided they were afebrile; had no new lesions for 24 h; had no internal organ involvement and were able to tolerate oral medications. Patients were observed in hospital for a further 24 h and then discharged provided they remained well. Oral acyclovir was continued for a total of 7 to 10 days (i.v. plus p.o). RESULTS Of the 26 patients 25 were successfully switched from i.v. to p.o after 4.1 +/- 1.2 days (mean +/- SD) (range, 2.3 to 6) Children had fever for a mean of 2.0 +/- 1.6 days (range, 0 to 5) and developed new lesions for 2.9 +/- 0.7 days (range, 2 to 4). All 25 patients switched to p.o therapy had resolution of their disease and no patient required resumption of i.v. therapy. CONCLUSIONS The sequential use of i.v. followed by p.o acyclovir is feasible in the treatment of varicella in immunocompromised children and results in a reduction in duration of intravenous therapy and hospitalization.
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Affiliation(s)
- M D Carcao
- Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada
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Carcao MD, Zipursky A, Butchart S, Leaker M, Blanchette VS. Short-course oral prednisone therapy in children presenting with acute immune thrombocytopenic purpura (ITP). Acta Paediatr Suppl 1998; 424:71-4. [PMID: 9736224 DOI: 10.1111/j.1651-2227.1998.tb01239.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Immune thrombocytopenic purpura (ITP) is a disorder for which management remains controversial. The ongoing goal is to define the minimal therapy required for children with acute ITP. A pilot study of short-course oral prednisone (4 mg(-1) kg(-1) d(-1) for 4 d with no tapering) was undertaken in 25 consecutive children with acute ITP and platelet counts under 20 x 10(9) l(-1). Of the 25 children, 22 responded to the prednisone therapy by achieving a platelet count higher than 20 x 10(9) l(-1) within 1 week of commencing treatment. This regimen was found to be safe, inexpensive and effective in increasing the platelet count of children to a haemostatically safe level.
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Affiliation(s)
- M D Carcao
- Department of Paediatrics, The Hospital for Sick Children and the University of Toronto, Ontario, Canada
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Carcao MD, Blanchette VS, Dean JA, He L, Kern MA, Stain AM, Sparling CR, Stephens D, Ryan G, Freedman J, Rand ML. The Platelet Function Analyzer (PFA-100): a novel in-vitro system for evaluation of primary haemostasis in children. Br J Haematol 1998; 101:70-3. [PMID: 9576184 DOI: 10.1046/j.1365-2141.1998.00656.x] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The PFA-100 system provides an in-vitro method of assessing primary platelet-related haemostasis by measuring the time (the closure time, or CT) taken for a platelet plug to occlude a microscopic aperture cut into a membrane coated with collagen and either epinephrine or ADP. We used the system to establish normal ranges for CTs in healthy children, adults and neonates. Mean CTs of healthy children were independent of the needle gauge used (21G or 23CG) for blood sampling; they were very similar to the mean CTs of healthy adults, but longer than mean CTs of healthy neonates. Although children with haemophilia had normal CTs, the PFA-100 system was found to be potentially useful in screening for von Willebrand disease in children.
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Affiliation(s)
- M D Carcao
- Division of Haematology/Oncology, The Hospital for Sick Children, Toronto, ON, Canada
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