ABSTRACT Background: Human aplastic anemia is a hematologic disease characterized by low peripheral blood cell counts associated with reduced numbers of hematopoietic stem and progenitor cells and a hypocellular bone marrow. Thrombopoietin (THPO) regulates megakaryocytes, but it also stimulates hematopoietic stem and progenitor cells. Biallelic mutations in the THPO gene have been reported in a family with recessive inherited aplastic anemia. Methods: This study screened 83 patients diagnosed with acquired aplastic anemia and 92 paired healthy controls for germline variants in the THPO gene using Sanger sequencing. Results: Three common single nucleotide polymorphisms were identified in patients and controls at comparable allele frequencies. There was no correlation between the single nucleotide polymorphism carrier status and platelet counts at diagnosis. Conclusion: The presence of THPO polymorphisms is comparable between patients with acquired aplastic anemia and healthy individuals.

Background: Paroxysmal nocturnal hemoglobinuria is an acquired chronic hemolytic ane- mia, which often manifests as peripheral blood cytopenias and thrombosis. Objective: The aim of this study is to describe a Brazilian population of paroxysmal nocturnal hemoglobinuria patients. Methods: One hundred and three paroxysmal nocturnal hemoglobinuria cases were retrospectively reviewed and the clinical presentation, thrombosis, survival, and clone size were assessed. Diagnosis was established by flow cytometry. Results: Fifty-two male and 51 female patients with a median age of 24.1 years (5.5-62 years) were studied. Clinical symptoms included hemoglobinuria (18.4%), infection (46.6%) and thrombosis (16.5%), and 80.6% had pancytopenia. Patients were classified as classic parox- ysmal nocturnal hemoglobinuria (10), paroxysmal nocturnal hemoglobinuria with aplastic anemia (39), and paroxysmal nocturnal hemoglobinuria with subclinical features and aplas- tic anemia (54). There were significant differences in terms of median age, size of clone, clinical symptoms, and peripheral blood cell counts between the three subcategories. The clone size in erythrocytes and granulocytes were respectively 0.04% (range: 0-18%) and 7.3% (range: 0.3-68.7%) in patients with subclinical features and aplastic anemia, 15.8% (range: 0-99.7%) and 63.0% (range: 1.7-99.8%) in patients with aplastic anemia alone, and 82.2% (range: 0-99.85%) and 98.0% (81.3-100.0%) in Classic disease. Statistical differences were identified for platelets (p-value = 0.001), lactate dehydrogenase (p-value = 0.002) and the clone size (p-value < 0.001) in patients who suffered thrombotic events compared to those who did not. Overall survival was 81.7%, with patients with subclinical features and aplastic anemia having lower overall survival (76.5%). Conclusion: This retrospective review of 103 patients over an 11-year period represents the largest collection of paroxysmal nocturnal hemoglobinuria cases from a single center in Brazil. Flow cytometry showed that a larger clone was associated with classical symptoms and increased risk of thrombosis, even in patients with bone marrow failure, whereas a smaller clone was associated with bone marrow aplasia.

O transplante de células-tronco hematopoéticas (TCTH) é o tratamento de escolha para leucemias agudas de alto risco. Apesar da melhora na sobrevida destes pacientes, a recidiva continua sendo a maior causa de óbito pós-transplante de células-tronco hematopoéticas. O objetivo deste trabalho foi analisar os resultados dos transplantes realizados em crianças com leucemia aguda em duas instituições brasileiras. Realizou-se estudo retrospectivo de 208 pacientes transplantados entre 1990-2007. Mediana de idade: 9 anos; 119 pacientes com leucemia linfoide aguda (LLA) e 89 com leucemia mieloide aguda (LMA). Doença precoce: CR1 e CR2. Doença avançada: >CR3, doença refratária ou recidivada. Noventa pacientes vivos entre 258-6.068 dias (M:1.438), com sobrevida global (SG) de 45% (3 anos) e a sobrevida livre de recaída (SLR) 39% (três anos). 14/195 pacientes tiveram falha primária de pega (8%). Não houve diferença na sobrevida global e sobrevida livre de recaída entre pacientes com leucemia linfoide aguda e leucemia mieloide aguda, entre transplantes aparentados e não aparentados, tampouco entre as fontes de células utilizadas. O desenvolvimento da doença do enxerto contra hospedeiro (DECH) aguda ou crônica também não influenciou a sobrevida global e sobrevida livre de recaída. Pacientes com leucemia linfoide aguda condicionados com irradiação corporal total (TBI) apresentaram melhor sobrevida global e sobrevida livre de recaída (p<0,001). Cento e dezoito pacientes morreram entre 1-1.654 dias pós-transplante de células-tronco hematopoéticas (M:160). Mortalidade relacionada a transplante (MRT) (dia+100): 16%. Incidência cumulativa de recaída: 40% (3 anos). Pacientes com doença avançada tiveram menor sobrevida global e sobrevida livre de recaída (três anos)(p<0,001). Na análise multivariada, o status da doença foi o principal fator associado ao aumento da sobrevida global e sobrevida livre de recaída. Nossos resultados mostram que é possível se atingir uma boa sobrevida para pacientes com doença precoce e também mostram a baixa eficácia naqueles com doença avançada.

Hematopoietic Stem Cell transplantation (HSCT) is the treatment of choice for patients with high-risk leukemia. In spite of this, relapse remains a major cause of death of these patients. Our objective was to analyze the outcomes of patients with acute leukemia submitted to hematopoietic stem cell transplantation in two Brazilian institutions. A retrospective study of 208 patients transplanted between 1990 and 2007 with a median age of 9 years (range: 1-18 years) was made. One hundred and nineteen patients had acute lymphocytic leukemia (ALL) and 89 had acute myeloid leukemia (AML). Early disease was considered for CR1 and CR2 cases and advanced disease >CR3 and refractory and relapse disease. Ninety patients are alive between 258 and 6068 days after hematopoietic stem cell transplantation (M: 1438 days). The overall survival (OS) was 45% (3 years) and event free survival (EFS) was 39% (3 years). Primary graft failure occurred in 14/195 patients (8%). There were no differences in the overall survival and event free survival between patients with acute lymphocytic leukemia and acute myeloid leukemia, between sources of cells used or between those who developed acute or chronic graft-versus-host disease (GVHD). When comparing transplants from related and unrelated donors, there was no difference in the overall survival. Patients with acute lymphocytic leukemia receiving the total body irradiation (TBI) conditioning regimen had better overall survival and event free survival (p<0.001). One hundred and eighteen patients died between 0 and 1654 days after hematopoietic stem cell transplantation (M: 160 days). Transplantation-related-mortality (TRM) at D+100 was 16% and cumulative incidence of relapse was 40% (3 years). Patients with advanced disease had lower 3-year overall survival and event free survival (p<0.001). Multivariate analysis showed that disease status was the most significant factor associated with higher event free survival and overall survival . Our results show that children and adolescents transplanted with early disease can achieve considerable overall survival and also highlights the inefficacy of hematopoietic stem cell transplantation for patients with advanced disease.