Pyruvate kinase deficiency in 29 Turkish patients with two novel intronic variants.

Pyruvate kinase (PK) is a key enzyme of anaerobic glycolysis. The genetic heterogeneity of PK deficiency (PKD) is high, and over 400 unique variants have been identified. Twenty-nine patients who had been diagnosed as PKD genetically in seven distinct paediatric haematology departments were evaluated. Fifteen of 23 patients (65.2%) had low PK levels. The PK:hexokinase ratio had 100% sensitivity for PKD diagnosis, superior to PK enzyme assay. Two novel intronic variants (c.695-1G>A and c.694+43C>T) have been described. PKD should be suspected in patients with chronic non-spherocytic haemolytic anaemia, even if enzyme levels are falsely normal. Total PKLR gene sequencing is necessary for the characterization of patients with PKD and for genetic counselling.

COVID-19 disease in children and adolescents following allogeneic hematopoietic stem cell transplantation: A report from the Turkish pediatric bone marrow transplantation study group.

BACKGROUND: Data on the risk factors and outcomes for pediatric patients with SARS-CoV-2 infection (COVID-19) following hematopoietic stem cell transplantation (HSCT) are limited. OBJECTIVES: The study aimed to analyze the clinical signs, risk factors, and outcomes for ICU admission and mortality in a large pediatric cohort who underwent allogeneic HSCT prior to COVID-19 infection. METHOD: In this nationwide study, we retrospectively reviewed the data of 184 pediatric HSCT recipients who had COVID-19 between March 2020 and August 2022. RESULTS: The median time from HSCT to COVID-19 infection was 209.0 days (IQR, 111.7-340.8; range, 0-3845 days). The most common clinical manifestation was fever (58.7%). While most patients (78.8%) had asymptomatic/mild disease, the disease severity was moderate in 9.2% and severe and critical in 4.4% and 7.6%, respectively. The overall mortality was 10.9% (n: 20). Deaths were attributable to COVID-19 in nine (4.9%) patients. Multivariate analysis revealed that lower respiratory tract disease (LRTD) (OR, 23.20, p: .001) and lymphopenia at diagnosis (OR, 5.21, p: .006) were risk factors for ICU admission and that HSCT from a mismatched donor (OR, 54.04, p: .028), multisystem inflammatory syndrome in children (MIS-C) (OR, 31.07, p: .003), and LRTD (OR, 10.11, p: .035) were associated with a higher risk for COVID-19-related mortality. CONCLUSION: While COVID-19 is mostly asymptomatic or mild in pediatric transplant recipients, it can cause ICU admission in those with LRTD or lymphopenia at diagnosis and may be more fatal in those who are transplanted from a mismatched donor and those who develop MIS-C or LRTD.

Central nervous system thrombosis in pediatric acute lymphoblastic leukemia in Turkey: A multicenter study.

BACKGROUND: In patients with acute lymphoblastic leukemia (ALL), the risk of thromboembolism increases due to hemostatic changes secondary to the primary disease and due to treatment-related factors. In this multicenter study, we aimed to research the frequency of central nervous system (CNS) thrombosis occurring during treatment, hereditary and acquired risk factors, clinical and laboratory features of patients with thrombosis, treatment approaches, and thrombosis-related mortality and morbidity rates in pediatric ALL patients. PROCEDURE: Pediatric patients who developed CNS thrombosis during ALL treatment from 2010 to 2021 were analyzed retrospectively in 25 different Pediatric Hematology Oncology centers in Türkiye. The demographic characteristics of the patients, symptoms associated with thrombosis, the stage of the leukemia treatment during thrombosis, the anticoagulant therapy applied for thrombosis, and the final status of the patients recorded through electronic medical records were determined. RESULTS: Data from 70 patients with CNS thrombosis during treatment, out of 3968 pediatric patients with ALL, were reviewed. The incidence of CNS thrombosis was 1.8% (venous: 1.5 %; arterial: 0.03%). Among patients with CNS thrombosis, 47 had the event in the first 2 months. Low molecular weight heparin (LMWH) was the most commonly used treatment with a median of 6 months (min-max: 3-28 months). No treatment-related complications occurred. Chronic thrombosis findings occurred in four patients (6%). In five (7%) patients who developed cerebral vein thrombosis, neurological sequelae (epilepsy and neurological deficit) remained. One patient died related to thrombosis, and the mortality rate was 1.4%. CONCLUSION: Cerebral venous thrombosis and, less frequently, cerebral arterial thrombosis may develop in patients with ALL. The incidence of CNS thrombosis is higher during induction therapy than during other courses of treatment. Therefore, patients receiving induction therapy should be monitored carefully for clinical findings suggestive of CNS thrombosis.

Assessment of Minimal Residual Disease in Childhood Acute Lymphoblastic Leukemia: A Multicenter Study From Turkey.

Assestment of minimal residual disease (MRD) in childhood acute lymphoblastic leukemia (ALL) is of utmost importance both for risk classification and tailoring of the therapy. The data of pediatric ALL patients that received treatment with Berlin-Frankfurt-Münster (BFM) protocols were retrospectively collected from 5 university hospitals in Turkey. Of the 1388 patients enrolled in the study 390 were treated according to MRD-based protocols. MRD assestment was with real time quantitative polymerase chain reaction (qPCR) in 283 patients and with multiparametric flow cytometry (MFC)-MRD in 107 patients. MRD monitoring had upstaged a total of 8 patients (2%) from intermediate risk group to high-risk group. Univariate analysis revealed age 10 years or above, prednisone poor response, PCR-MRD ≥10-3 on day 33 and on day 78 as poor prognostic factors affecting event-free survival (EFS). Detection of >10% blasts on day 15 with MFC (MFC-high-risk group) was not shown to affect EFS and/or overall survival (log-rank P=0.339). Multiple logistic regression analysis revealed PCR-MRD ≥10-3 on day 78 as the only poor prognostic factor affecting EFS (odds ratio: 8.03; 95% confidence interval: 2.5-25; P=0.000). It is very important to establish the infrastructure and ensure necessary standardization for both MRD methods for optimal management of children with ALL.

Different Kinetics and Risk Factors for Isolated Extramedullary Relapse after Allogeneic Hematopoietic Stem Cell Transplantation in Children with Acute Leukemia.

Relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the most frequent cause of post-transplantation mortality. Isolated extramedullary (EM) relapse (iEMR) after HSCT is relatively rare and not well characterized, particularly in pediatric patients. We retrospectively analyzed 1527 consecutive pediatric patients with acute leukemia after allo-HSCT to study the incidence, risk factors, and outcome of iEMR compared with systemic relapse. The 5-year cumulative incidence of systemic relapse (either bone marrow [BM] only or BM combined with EMR) was 24.8%, and that of iEMR was 5.5%. The onset of relapse after allo-HSCT was significantly longer in EM sites than in BM sites (7.19 and 5.58 months, respectively; P = .013). Complete response (CR) 2+/active disease at transplantation (hazard ratio [HR], 3.1; P < .001) and prior EM disease (HR, 2.3; P = .007) were independent risk factors for iEMR. Chronic graft-versus-host disease reduced the risk of systemic relapse (HR, 0.5; P = .043) but did not protect against iEMR. The prognosis of patients who developed iEMR remained poor but was slightly better than that of patients who developed systemic relapse (3-year overall survival, 16.5% versus 15.3%; P = .089). Patients experiencing their first systemic relapse continued to have further systemic relapse, but only a minority progressed to iEMR, whereas those experiencing their iEMR at first relapse developed further systemic relapse and iEMR at approximately similar frequencies. A second iEMR was more common after a first iEMR than after a first systemic relapse (58.8% versus 13.0%; P = .001) and was associated with poor outcome. iEMR has a poor prognosis, particularly after a second relapse, and effective strategies are needed to improve outcomes.

Preliminary Data on COVID-19 in Patients with Hemoglobinopathies: A Multicentre ICET-A Study.

OBJECTIVES: This study aims to investigate, retrospectively, the epidemiological and clinical characteristics, laboratory results, radiologic findings, and outcomes of COVID-19 in patients with transfusion-dependent ß thalassemia major (TM), ß-thalassemia intermedia (TI) and sickle cell disease (SCD). DESIGN: A total of 17 Centers, from 10 countries, following 9,499 patients with hemoglobinopathies, participated in the survey. MAIN OUTCOME DATA: Clinical, laboratory, and radiologic findings and outcomes of patients with COVID-19 were collected from medical records and summarized. RESULTS: A total of 13 patients, 7 with TM, 3 with TI, and 3 with SCD, with confirmed COVID-19, were identified in 6 Centers from different countries. The overall mean age of patients was 33.7±12.3 years (range:13-66); 9/13 (69.2%) patients were females. Six patients had pneumonia, and 4 needed oxygen therapy. Increased C-reactive protein (6/10), high serum lactate dehydrogenase (LDH; 6/10), and erythrocyte sedimentation rate (ESR; 6/10) were the most common laboratory findings. 6/10 patients had an exacerbation of anemia (2 with SCD). In the majority of patients, the course of COVID-19 was moderate (6/10) and severe in 3/10 patients. A 30-year-old female with TM, developed a critical SARS-CoV-2 infection, followed by death in an Intensive Care Unit. In one Center (Oman), the majority of suspected cases were observed in patients with SCD between the age of 21 and 40 years. A rapid clinical improvement of tachypnea/dyspnea and oxygen saturation was observed, after red blood cell exchange transfusion, in a young girl with SCD and worsening of anemia (Hb level from 9.2 g/dl to 6.1g/dl). CONCLUSIONS: The data presented in this survey permit an early assessment of the clinical characteristics of COVID 19 in different countries. 70% of symptomatic patients with COVID- 19 required hospitalization. The presence of associated co-morbidities can aggravate the severity of COVID- 19, leading to a poorer prognosis irrespective of age.

Acute Central Nervous System Complications in Pediatric Acute Lymphoblastic Leukemia.

BACKGROUND: The outcome of childhood acute lymphoblastic leukemia has improved because of intensive chemotherapy and supportive care. The frequency of adverse events has also increased, but the data related to acute central nervous system complications during acute lymphoblastic leukemia treatment are sparse. The purpose of this study is to evaluate these complications and to determine their long term outcome. PATIENTS AND METHODS: We retrospectively analyzed the hospital reports of 323 children with de novo acute lymphoblastic leukemia from a 13-year period for acute neurological complications. The central nervous system complications of leukemic involvement, peripheral neuropathy, and post-treatment late-onset encephalopathy, and neurocognitive defects were excluded. RESULTS: Twenty-three of 323 children (7.1%) suffered from central nervous system complications during acute lymphoblastic leukemia treatment. The majority of these complications (n = 13/23; 56.5%) developed during the induction period. The complications included posterior reversible encephalopathy (n = 6), fungal abscess (n = 5), cerebrovascular lesions (n = 5), syndrome of inappropriate secretion of antidiuretic hormone (n = 4), and methotrexate encephalopathy (n = 3). Three of these 23 children (13%) died of central nervous system complications, one from an intracranial fungal abscess and the others from intracranial thrombosis. Seven of the survivors (n = 7/20; 35%) became epileptic and three of them had also developed mental and motor retardation. CONCLUSIONS: Acute central neurological complications are varied and require an urgent approach for proper diagnosis and treatment. Collaboration among the hematologist, radiologist, neurologist, microbiologist, and neurosurgeon is essential to prevent fatal outcome and serious morbidity.

The long-term results of childhood acute lymphoblastic leukemia at two centers from Turkey: 15 years of experience with the ALL-BFM 95 protocol.

Dramatic progress in the treatment of childhood acute lymphoblastic leukemia (ALL) has been achieved during the last two decades in Western countries, where the 5-year event-free survival (EFS) rate has risen from 30 to 85 %. However, similarly high cure rates have not always been achieved in all centers in developing countries due to limited sources. We evaluated the treatment results of the ALL-Berlin-Frankfurt-Münster (BFM) 95 protocol as used between 1995 and 2009 in the pediatric hematology departments of two university hospitals. A retrospective analysis of 343 children newly diagnosed with ALL (M/F 200/143, median age 6.8 years) was performed. The overall survival (OS) and EFS according to age, initial leukocyte count, immunophenotype, chemotherapy responses (on days 8, 15, and 33), and risk groups were analyzed by Kaplan-Meier survival analysis. Median follow-up time was 6.4 years. Complete remission was achieved in 97 % of children. Five-year EFS and OS were found to be 78.4 and 79.9 %, respectively. Children younger than 6 years old had significantly better EFS and OS (83.7 and 85.2 %) than children aged ≥6 years (71.4 and 72.8 %). Adolescents achieved 63 % EFS and 65 % OS. Patients who had initial leukocyte counts of <20 × 10(9)/L had better EFS and OS (82.2 and 84.6 %) than children with higher initial leukocyte counts (72.6 and 72.6 %). EFS for B-cell precursor and T-cell ALL was 81.5 and 66.7 %, respectively. Children with a good response to prednisolone on day 8 (87 %) achieved significantly better EFS and OS (81.2 and 81.9 % vs. 55.3 and 60.5 %). Children whose bone marrow on day 15 was in complete remission had higher EFS and OS (83.7 and 86.6.1 % vs. 56.4 and 61.5 %). Children in the standard-risk and medium-risk groups obtained statistically significantly higher EFS (95.5 and 82.7 %) and OS (97.7 and 82.3 %) compared to the high-risk group (EFS 56.3 %, OS 63.4 %). The relapse rate was 14.8 %. The median relapse time from diagnosis was 23.2 months. Death occurred in 69 of 343 patients (20.1 %). The major causes of death were infection and relapse. None of the patients died of drug-related toxicity. The ALL-BFM 95 protocol was applied successfully in these two centers. In developing countries in which minimal residual disease cannot be monitored, this protocol can still be used with high survival rates.

Childhood Immune Thrombocytopenia: Long-term Follow-up Data Evaluated by the Criteria of the International Working Group on Immune Thrombocytopenic Purpura.

OBJECTIVE: Immune thrombocytopenia (ITP) is a common bleeding disorder in childhood, characterized by isolated thrombocytopenia. The International Working Group (IWG) on ITP recently published a consensus report about the standardization of terminology, definitions, and outcome criteria in ITP to overcome the difficulties in these areas. MATERIALS AND METHODS: The records of patients were retrospectively collected from January 2000 to December 2009 to evaluate the data of children with ITP by using the new definitions of the IWG. RESULTS: The data of 201 children were included in the study. The median follow-up period was 22 months (range: 12-131 months). The median age and platelet count at presentation were 69 months (range: 7-208 months) and 19x10(9)/L (range: 1x10(9)/L to 93x10(9)/L), respectively. We found 2 risk factors for chronic course of ITP: female sex (OR=2.55, CI=1.31-4.95) and age being more than 10 years (OR=3.0, CI=1.5-5.98). Life-threatening bleeding occurred in 5% (n=9) of the patients. Splenectomy was required in 7 (3%) cases. When we excluded 2 splenectomized cases, complete remission at 1 year was achieved in 70% (n=139/199). The disease was resolved in 9 more children between 12 and 90 months. CONCLUSION: Female sex and age above 10 years old significantly influenced chronicity. Therefore, long-term follow-up is necessary in these children.

Thrombolysis with recombinant tissue plasminogen activator in 7 children.

The information about the thromboembolic events, the optimal treatment choice, the dose, and duration of antithrombotic therapy in children are limited. More clinical data are required. Recombinant tissue plasminogen activator (r-tPA) is increasingly used in pediatric thrombosis. We retrospectively analyzed the clinical course of 7 children (9.3 ± 2.1 years; 34 days to 16 years) with arterial thrombosis (n = 1) and intracardiac thrombosis (n = 6). The children were treated with r-tPA. The dose ranged between 0.2 and 0.4 mg/kg per h infused for 3 to 4 hours. This dose was repeated between 2 to 7 times till the thrombolysis was achieved. Treatment side effects were closely monitored. Complete clot lysis was achieved in all cases. None of them had severe bleeding except mild recurrent epistaxis occurring in 2 cases. In conclusion, r-tPA is an effective and safe therapy under close hemostatic control in children.

Cerebellar granulocytic sarcoma: a case report.

Granulocytic sarcoma is a rare tumor composed of immature granulocytic cells that is usually associated with acute myelogenous leukemia. Intraparenchymal cranial localization without skull, meningeal, or bone marrow invasion is extremely rare. The mechanisms of intraparenchymal cranial localization of GS remains unknown, as only 10 cases with cerebellar granulocytic sarcoma have been previously reported. Herein, we report a four year old boy with cerebellar localization of granulocytic sarcoma.

Reversible posterior leukoencephalopathy induced by cancer chemotherapy.

Reversible posterior leukoencephalopathy, defined by both clinical and neuroimaging findings, can affect children receiving chemotherapy. The syndrome is characterized by hypertension, alterations in mental status, seizures, hallucinations, and acute visual changes and is associated with abnormalities seen in magnetic resonance imaging of symmetric white matter lesions, especially in the parietal and occipital lobes. The etiology of reversible posterior leukoencephalopathy is as yet unknown. Presented here are four cases of reversible posterior leukoencephalopathy induced by chemotherapy, with a brief review of the literature and consideration of possible mechanisms. A diagnosis of reversible posterior leukoencephalopathy should be considered when patients receiving cancer chemotherapy suddenly develop hypertension followed by neurologic complications, especially if presenting with seizures.