Elevated erythroferrone distinguishes erythrocytosis with inherited defects in oxygen-sensing pathway from primary familial and congenital polycythaemia.

Congenital erythrocytoses represent a heterogenous group of rare defects of erythropoiesis characterized by elevated erythrocyte mass. We performed molecular-genetic analysis of 21 Czech patients with congenital erythrocytosis and assessed the mutual link between chronic erythrocyte overproduction and iron homoeostasis. Causative mutations in erythropoietin receptor (EPOR), hypoxia-inducible factor 2 alpha (HIF2A) or Von Hippel-Lindau (VHL) genes were detected in nine patients, including a novel p.A421Cfs*4 EPOR and a homozygous intronic c.340+770T>C VHL mutation. The association and possible cooperation of five identified missense germline EPOR or Janus kinase 2 (JAK2) variants with other genetic/non-genetic factors in erythrocytosis manifestation may involve variants of Piezo-type mechanosensitive ion channel component 1 (PIEZO1) or Ten-eleven translocation 2 (TET2), but this requires further research. In two families, hepcidin levels appeared to prevent or promote phenotypic expression of the disease. No major contribution of heterozygous haemochromatosis gene (HFE) mutations to the erythrocytic phenotype or hepcidin levels was observed in our cohort. VHL- and HIF2A-mutant erythrocytosis showed increased erythroferrone and suppressed hepcidin, whereas no overproduction of erythroferrone was detected in other patients regardless of molecular defect, age or therapy. Understanding the interplay between iron metabolism and erythropoiesis in different subgroups of congenital erythrocytosis may improve current treatment options.

Missense mutation in RPS7 causes Diamond-Blackfan anemia via alteration of erythrocyte metabolism, protein translation and induction of ribosomal stress.

Diamond-Blackfan anemia (DBA) is predominantly underlined by mutations in genes encoding ribosomal proteins (RP); however, its etiology remains unexplained in approximately 25 % of patients. We previously reported a novel heterozygous RPS7 mutation hg38 chr2:g.3,580,153G > T p.V134F in one female patient and two asymptomatic family members, in whom mild anemia and increased erythrocyte adenosine deaminase (eADA) activity were detected. We observed that altered erythrocyte metabolism and oxidative stress which may negatively affect the lifespan of erythrocytes distinguishes the patient from her asymptomatic family members. Pathogenicity of the RPS7 p.V134F mutation was extensively validated including molecular defects in protein translational activity and ribosomal stress activation in the cellular model of this variant.

Genotype-phenotype association and variant characterization in Diamond-Blackfan anemia caused by pathogenic variants in RPL35A.

Diamond Blackfan anemia (DBA) is predominantly an autosomal dominant inherited red cell aplasia primarily caused by pathogenic germline variants in ribosomal protein genes. DBA due to pathogenic RPL35A variants has been associated with large 3q29 deletions and phenotypes not common in DBA. We conducted a multi-institutional genotype-phenotype study of 45 patients with DBA associated with pathogenic RPL35A germline variants and curated the variant data on 21 additional cases from the literature. Genotype-phenotype analyses were conducted comparing patients with large deletions versus all other pathogenic variants in RPL35A. Twenty-two of the 45 cases had large deletions in RPL35A. After adjusting for multiple tests, a statistically significant association was observed between patients with a large deletion and steroid-resistant anemia, neutropenia, craniofacial abnormalities, chronic gastrointestinal problems, and intellectual disabilities (p<0.01) compared with all other pathogenic variants. Non-large deletion pathogenic variants were spread across RPL35A with no apparent hot spot and 56% of the individual family variants were observed more than once. In this, the largest known study of DBA patients with pathogenic RPL35A variants, we determined that patients with large deletions have a more severe phenotype that is clinically different from those with non-large deletion variants. Genes of interest also deleted in the 3q29 region that could be associated with some of these phenotypic features include LMLN and IQCG. Management of DBA due to large RPL35A deletions may be challenging due to complex problems and require comprehensive assessments by multiple specialists including immunologic, gastrointestinal, and developmental evaluations to provide optimal multidisciplinary care.

Importance of Hepcidin in the Etiopathogenesis of Anemia in Inflammatory Bowel Disease.

Anemia is the most common extraintestinal systemic complication of inflammatory bowel disease. Iron deficiency anemia and anemia of chronic disease are among the most frequent types. Intestinal iron absorption is controlled by the activity of ferroportin. Cells with high expression of ferroportin include enterocytes, and also macrophages and hepatocytes. Iron homeostasis is controlled by the hepcidin-ferroportin axis. Hepcidin is a central regulator of iron metabolism and can also serve as a marker of systemic inflammation. During systemic inflammatory response, the synthesis of hepcidin increases, and hepcidin binds to ferroportin and inhibits its activity. Thus, iron is not absorbed from the bowel into the circulation and also remains sequestered in macrophages. Conversely, hepcidin synthesis is suppressed during conditions requiring increased iron intake for enhanced erythropoiesis, such as iron deficiency anemia or hypoxia. Here, ferroportin is not blocked, and iron is actively absorbed into the bloodstream and also released from the stores. Production of hepcidin is influenced by the status of total body iron stores, systemic inflammatory activity and erythropoietic activity. Oral iron therapy is limited in inflammatory bowel diseases due to ongoing gastrointestinal inflammation. It is less effective and may worsen the underlying disease. Therefore, the choice between oral and parenteral iron therapy must be made with caution. Oral iron would be ineffective at high hepcidin levels due to concurrent ferroportin blockage. Contrarily, low levels of hepcidin indicate that oral iron therapy should be successful. An understanding of hepcidin can help in understanding the body's reaction to iron depletion during the inflammatory process.

Czech and Slovak Diamond-Blackfan Anemia (DBA) Registry update: Clinical data and novel causative genetic lesions.

Diamond-Blackfan anemia (DBA) is a rare congenital erythroid aplasia, underlied by haploinsufficient mutations in genes coding for ribosomal proteins (RP) in approximately 70% of cases. DBA is frequently associated with somatic malformations, endocrine dysfunction and with an increased predisposition to cancer. Here we present clinical and genetic characteristics of 62 patients from 52 families enrolled in the Czech and Slovak DBA Registry. Whole exome sequencing (WES) and array comparative genomic hybridization (aCGH) were employed to identify causative mutations in newly diagnosed patients and in cases with previously unrecognized molecular pathology. RP mutation detection rate was 81% (50/62 patients). This included 8 novel point mutations and 4 large deletions encompassing some of the RP genes. Malignant or predisposing condition developed in 8/62 patients (13%): myelodysplastic syndrome in 3 patients; breast cancer in 2 patients; colorectal cancer plus ocular tumor, diffuse large B-cell lymphoma and multiple myeloma each in one case. These patients exclusively harbored RPL5, RPL11 or RPS19 mutations. Array CGH is beneficial for detection of novel mutations in DBA due to its capacity to detect larger chromosomal aberrations. Despite the importance of genotype-phenotype correlation in DBA, phenotypic differences among family members harboring an identical mutation were observed.

Clinical spectrum of pyruvate kinase deficiency: data from the Pyruvate Kinase Deficiency Natural History Study.

An international, multicenter registry was established to collect retrospective and prospective clinical data on patients with pyruvate kinase (PK) deficiency, the most common glycolytic defect causing congenital nonspherocytic hemolytic anemia. Medical history and laboratory and radiologic data were retrospectively collected at enrollment for 254 patients with molecularly confirmed PK deficiency. Perinatal complications were common, including anemia that required transfusions, hyperbilirubinemia, hydrops, and prematurity. Nearly all newborns were treated with phototherapy (93%), and many were treated with exchange transfusions (46%). Children age 5 years and younger were often transfused until splenectomy. Splenectomy (150 [59%] of 254 patients) was associated with a median increase in hemoglobin of 1.6 g/dL and a decreased transfusion burden in 90% of patients. Predictors of a response to splenectomy included higher presplenectomy hemoglobin (P = .007), lower indirect bilirubin (P = .005), and missense PKLR mutations (P = .0017). Postsplenectomy thrombosis was reported in 11% of patients. The most frequent complications included iron overload (48%) and gallstones (45%), but other complications such as aplastic crises, osteopenia/bone fragility, extramedullary hematopoiesis, postsplenectomy sepsis, pulmonary hypertension, and leg ulcers were not uncommon. Overall, 87 (34%) of 254 patients had both a splenectomy and cholecystectomy. In those who had a splenectomy without simultaneous cholecystectomy, 48% later required a cholecystectomy. Although the risk of complications increases with severity of anemia and a genotype-phenotype relationship was observed, complications were common in all patients with PK deficiency. Diagnostic testing for PK deficiency should be considered in patients with apparent congenital hemolytic anemia and close monitoring for iron overload, gallstones, and other complications is needed regardless of baseline hemoglobin. This trial was registered at www.clinicaltrials.gov as #NCT02053480.

Severe linezolid-induced lactic acidosis in a child with acute lymphoblastic leukemia: A case report.

Linezolid is an antibiotic increasingly used for treatment of resistant Gram-positive infections, which blocks bacterial proteosythesis through direct inhibition of mitochondrial ribosomes. The most common adverse effects of linezolid include gastrointestinal symtoms, peripheral neuropathy, bone marrow depression and lactic acidosis. Here we present a rare case of a 9-year-old female, a survivor of acute lymphoblastic leukemia (ALL) and a hematopoietic stem cell transplant (HSCT), who developed life-threatening lactic acidosis with vomiting, impaired consciousness and Kussmaul breathing after 51 days of intravenous linezolid administration due to mycobacterial infection. She fully recovered after drug discontinuation and normalization of the plasma levels. We conclude that plasma lactate concentrations should be monitored closely during any linezolid treatment, particularly in patients with hepatic or renal dysfunction.

Changes in serum hepcidin levels in children with inflammatory bowel disease during anti-inflammatory treatment.

AIM: The aim of this study was to compare changes in serum hepcidin levels in paediatric patients with inflammatory bowel disease during therapy and correlate them with markers of iron metabolism, inflammation and type of treatment. METHODS: Children with newly diagnosed Crohn's disease (CD) and ulcerative colitis (UC) were included in this longitudinal study. Blood and stool samples were collected to assess levels of serum hepcidin and markers of iron metabolism parameters and inflammation. The parameters were examined before treatment (baseline levels) and compared with levels in the follow-up period during maintenance therapy (mean follow-up of 39 months after diagnosis). RESULTS: Patients with CD (n = 30) had higher serum hepcidin levels (expressed as a median and interquartile range) at diagnosis than subjects with UC (n = 13). These levels significantly decreased during the follow-up (from 36.5 (11.5-79.6) to 2.1 (0.9-6.7) ng/mL). In contrast, no significant serum hepcidin level changes were observed in the UC patients (5.4 (3.4-16.6) vs. 4.8 (0.9-8.1) ng/mL). While hepcidin level changes correlated with disease activity and inflammatory parameters (erythrocyte sedimentation rate, C-reactive protein), in CD patients, they correlated only with serum iron levels in patients with UC. Biological therapy was accompanied by a significant decrease in C-reactive protein and interleukin-6 compared to conventional anti-inflammatory therapy in CD patients. CONCLUSIONS: Children with CD had higher serum hepcidin levels on diagnosis compared to subjects with UC. During an anti-inflammatory therapy, serum hepcidin decreased in the CD group but remained consistently low in children with UC.

Oxidative DNA Damage, Inflammatory Signature, and Altered Erythrocytes Properties in Diamond-Blackfan Anemia.

Molecular pathophysiology of Diamond-Blackfan anemia (DBA) involves disrupted erythroid-lineage proliferation, differentiation and apoptosis; with the activation of p53 considered as a key component. Recently, oxidative stress was proposed to play an important role in DBA pathophysiology as well. CRISPR/Cas9-created Rpl5- and Rps19-deficient murine erythroleukemia (MEL) cells and DBA patients' samples were used to evaluate proinflammatory cytokines, oxidative stress, DNA damage and DNA damage response. We demonstrated that the antioxidant defense capacity of Rp-mutant cells is insufficient to meet the greater reactive oxygen species (ROS) production which leads to oxidative DNA damage, cellular senescence and activation of DNA damage response signaling in the developing erythroblasts and altered characteristics of mature erythrocytes. We also showed that the disturbed balance between ROS formation and antioxidant defense is accompanied by the upregulation of proinflammatory cytokines. Finally, the alterations detected in the membrane of DBA erythrocytes may cause their enhanced recognition and destruction by reticuloendothelial macrophages, especially during infections. We propose that the extent of oxidative stress and the ability to activate antioxidant defense systems may contribute to high heterogeneity of clinical symptoms and response to therapy observed in DBA patients.

Two novel mutations (p.(Ser160Pro) and p.(Arg472Cys)) causing glucose-6-phosphate isomerase deficiency are associated with erythroid dysplasia and inappropriately suppressed hepcidin.

Glucose-6-phosphate isomerase (GPI) deficiency, a genetic disorder responsible for chronic nonspherocytic hemolytic anemia, is the second most common red blood cell glycolytic enzymopathy. We report three patients from two unrelated families of Czech and Slovak origin with macrocytic hemolytic anemia due to GPI deficiency. The first patient had 15% of residual GPI activity resulting from two new heterozygous missense mutations c.478T>C and c.1414C>T leading to substitutions p.(Ser160Pro) and p.(Arg472Cys). Two other patients (siblings) inherited the same c.1414C>T p.(Arg472Cys) mutation in a homozygous constitution and lost approximately 89% of their GPI activity. Erythroid hyperplasia with dysplastic features was observed in the bone marrow of all three patients. Low hepcidin/ferritin ratio and elevated soluble transferrin receptor detected in our GPI-deficient patients suggest disturbed balance between erythropoiesis and iron metabolism contributing to iron overload.

Cooperation of germ line JAK2 mutations E846D and R1063H in hereditary erythrocytosis with megakaryocytic atypia.

The role of somatic JAK2 mutations in clonal myeloproliferative neoplasms (MPNs) is well established. Recently, germ line JAK2 mutations were associated with polyclonal hereditary thrombocytosis and triple-negative MPNs. We studied a patient who inherited 2 heterozygous JAK2 mutations, E846D from the mother and R1063H from the father, and exhibited erythrocytosis and megakaryocytic atypia but normal platelet number. Culture of erythroid progenitors from the patient and his parents revealed hypersensitivity to erythropoietin (EPO). Using cellular models, we show that both E846D and R1063H variants lead to constitutive signaling (albeit much weaker than JAK2 V617F), and both weakly hyperactivate JAK2/STAT5 signaling only in the specific context of the EPO receptor (EPOR). JAK2 E846D exhibited slightly stronger effects than JAK2 R1063H and caused prolonged EPO-induced phosphorylation of JAK2/STAT5 via EPOR. We propose that JAK2 E846D predominantly contributes to erythrocytosis, but is not sufficient for the full pathological phenotype to develop. JAK2 R1063H, with very weak effect on JAK2/STAT5 signaling, is necessary to augment JAK2 activity caused by E846D above a threshold level leading to erythrocytosis with megakaryocyte abnormalities. Both mutations were detected in the germ line of rare polycythemia vera, as well as certain leukemia patients, suggesting that they might predispose to hematological malignancy.

Hepcidin in newly diagnosed inflammatory bowel disease in children.

AIM: Hepcidin is a central regulator of iron homeostasis. Its production is also influenced by systemic inflammation. The aims of this study were to compare hepcidin levels in paediatric patients newly diagnosed with Crohn's disease (CD) and ulcerative colitis (UC) and to determine the association of hepcidin levels with laboratory and clinical parameters of inflammatory bowel disease (IBD) activity. METHODS: Children with newly diagnosed IBD between January 2012 and September 2016 were enrolled in this comparative cross-sectional study. We analysed levels of serum hepcidin, C-reactive protein, iron, ferritin, soluble transferrin receptors, blood count and faecal calprotectin in all subjects. Serum hepcidin levels were measured by reverse-phase liquid chromatography. The Paediatric Crohn's Disease Activity Index was used to evaluate CD in children, and Paediatric Ulcerative Colitis Activity Index was used for the assessment of UC disease activity. RESULTS: Subjects with CD (n = 53) had significantly higher serum hepcidin levels compared with subjects with UC (n = 23) - 22.6 ng/mL (range 8.5-65.0) versus 6.5 ng/mL (range 2.4-25.8) (P < 0.05). Hepcidin was independently associated with ferritin levels in all IBD patients (P < 0.05). Moreover, there was a significant positive correlation between hepcidin and platelet count (P < 0.05) in children with CD and a negative correlation between hepcidin and faecal calprotectin (P < 0.05) in children with UC. CONCLUSION: Different hepcidin levels between children with newly diagnosed CD and UC suggest the distinct contribution of iron deficiency and/or systemic inflammation to anaemia and may help clinicians choose the best anti-anaemic treatment.

Rare anemias from the group of congenital bone marrow failure syndromes.

This review summarizes the pathophysiology, genetic background and clinical symptoms of anemias belonging to the group of inherited bone marrow failure syndromes with unilineage failure of erythropoiesis. It sums up the current knowledge of three diseases: Diamond-Blackfan anemia, congenital dyserythropoietic anemia and Fanconi anemia whose pathophysiology was elucidated in detail during the last decade, owing to the rapid development of new molecular-genetic techniques, especially next-generation sequencing. Fanconi anemia is included in this overview because of macrocytosis and/or anemia detected in the majority of the patients before they develop bone marrow failure. The paper also aims at pointing out typical associated anomalies in these diseases which might be overlooked and which can lead to early diagnosis. Unfortunately, the correct diagnosis is often established later in adulthood and, in some cases, as late as at the time of manifestation of malignant disease. Accurate and timely diagnosis of these conditions is extremely important for the determination of appropriate treatment approach, diagnosis of affected family members (especially in the process of bone marrow donor search), and genetic counselling, which can substantially influence the prognosis of these diseases. Key words: congenital dyserythropoietic anemia - Diamond-Blackfan anemia - DNA repair - dyserythropoiesis - Fanconi anemia - inherited bone marrow failure - ribosomopathies.

Hemoglobinopathies.

This article summarize molecular-genetic basis of hemoglobinopathies, their classification and phenotypic manifestations. The description of individual subgroups is supplemented with a case reports of patients diagnosed in the Czech population. This paper provides an overview of 14 types of α-thalassemic mutations, 34 ß-thalassemic alleles, 4 δß-thalassemic alleles and 22 hemoglobin variants identified in the Czech population in 876 persons from 579 families. In more detail are described hemoglobinopathies, that have been diagnosed and described as novel: ß-thalassemic mutation CD 38/39 (-C); Hb Olomouc; Hb Hana; Hb Hradec Kralove and 18.3 kb deletion downstream of α-globin cluster leading to a new mechanism of α-thalassemia-2. The fact that until the end of 2017 hemoglobinopathies were diagnosed in nearly 900 patients shows that they are not rare in the Czech Republic. This brings increased demands for their diagnostics, including prenatal diagnosis. Key words: hemoglobinopathies - hemoglobinopathy with high affinity to oxygen - sickle cell anemia - thalassemia - thalassemic hemoglobinopathy - unstable hemoglobins.

Recommendations regarding splenectomy in hereditary hemolytic anemias.

Hereditary hemolytic anemias are a group of disorders with a variety of causes, including red cell membrane defects, red blood cell enzyme disorders, congenital dyserythropoietic anemias, thalassemia syndromes and hemoglobinopathies. As damaged red blood cells passing through the red pulp of the spleen are removed by splenic macrophages, splenectomy is one possible therapeutic approach to the management of severely affected patients. However, except for hereditary spherocytosis for which the effectiveness of splenectomy has been well documented, the efficacy of splenectomy in other anemias within this group has yet to be determined and there are concerns regarding short- and long-term infectious and thrombotic complications. In light of the priorities identified by the European Hematology Association Roadmap we generated specific recommendations for each disorder, except thalassemia syndromes for which there are other, recent guidelines. Our recommendations are intended to enable clinicians to achieve better informed decisions on disease management by splenectomy, on the type of splenectomy and the possible consequences. As no randomized clinical trials, case control or cohort studies regarding splenectomy in these disorders were found in the literature, recommendations for each disease were based on expert opinion and were subsequently critically revised and modified by the Splenectomy in Rare Anemias Study Group, which includes hematologists caring for both adults and children.

Eltrombopag for children with chronic immune thrombocytopenia (PETIT2): a randomised, multicentre, placebo-controlled trial.

BACKGROUND: The thrombopoietin receptor agonist eltrombopag has been shown to be safe, tolerable, and effective for adults with chronic immune thrombocytopenia. We aimed to investigate the safety and efficacy of eltrombopag for children with chronic immune thrombocytopenia. METHODS: PETIT2 was a two part, randomised, multicentre, placebo-controlled study done at 38 centres in 12 countries (Argentina, Czech Republic, Germany, Hong Kong, Israel, Italy, Russia, Spain, Taiwan, Thailand, UK, and USA). Paediatric patients aged 1-17 years who had chronic immune thrombocytopenia and platelet counts less than 30 × 10(9) per L were randomly assigned (2:1) to receive eltrombopag or placebo. We stratified patients by age into three cohorts (patients aged 12-17 years, 6-11 years, and 1-5 years) before randomly entering them into a 13 week, double-blind period. Randomisation was done by the GlaxoSmithKline Registration and Medication Ordering System and both patients and study personnel were masked to treatment assignments. Patients who were allocated eltrombopag received tablets (except for those aged 1-5 years who received an oral suspension formulation) once per day for 13 weeks. Starting doses for patients aged 6-17 were based on bodyweight, and ethnic origin and ranged between 50 mg/day and 25 mg/day (starting dose for patients aged 1-5 years was 1·2 mg/kg/day or 0·8 mg/kg/day for east Asian patients). Patients who completed the double-blind period entered a 24 week open-label treatment period in which all patients received eltrombopag at either the starting dose (if they were formerly on placebo) or their established dose. The primary outcome was the proportion of patients achieving platelet counts of at least 50 × 10(9) per L in the absence of rescue therapy for 6 or more weeks from weeks 5 to 12 of the double-blind period. The intention-to-treat population included in the efficacy assessment consisted of all patients who were randomly assigned to one of the treatment groups, and the safety population included all patients who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, number NCT01520909. FINDINGS: Beginning in March 15, 2012, 92 patients were enrolled, and the trial was completed on Jan 2, 2014. 63 patients were assigned to receive eltrombopag and 29 were assigned to receive placebo. In the double-blind period, three patients discontinued treatment because of adverse events: two patients in the eltrombopag group withdrew because of increased liver aminotransferases and one in the placebo group withdrew because of abdominal haemorrhage. 25 (40%) patients who received eltrombopag compared with one (3%) patient who received placebo achieved the primary outcome of platelet counts of at least 50 × 10(9) per L for 6 of the last 8 weeks of the double-blind period (odds ratio 18·0, 95% CI, 2·3-140·9; p=0·0004). Responses were similar in all cohorts (eltrombopag vs placebo: 39% vs 10% for patients aged 12-17 years, 42% vs 0% for patients aged 6-11 years, and 36% vs 0% for patients aged 1-5 years). Proportionately fewer patients who received eltrombopag (23 [37%] of 63 patients) had WHO grades 1-4 bleeding at the end of the double-blind period than did those who received placebo (16 [55%] of 29 patients); grades 2-4 bleeding were similar (three [5%] patients who received eltrombopag vs two [7%] patients who received placebo). During the 24-week open-label treatment period, 70 [80%] of 87 patients achieved platelet counts of 50 × 10(9) per L or more at least once. Adverse events that occurred more frequently with eltrombopag than with placebo included nasopharyngitis (11 [17%] patients), rhinitis (10 [16%] patients), upper respiratory tract infection (7 [11%] patients), and cough (7 [11%] patients). Serious adverse events occurred in five (8%) patients who received eltrombopag and four (14%) who received placebo. Safety was consistent between the open-label and double-blind periods. No deaths, malignancies, or thromboses occurred during the trial. INTERPRETATION: Eltrombopag, which produced a sustained platelet response in 40% of patients with chronic immune thrombocytopenia, is a suitable therapeutic option for children with chronic symptomatic immune thrombocytopenia. We identified no new safety concerns and few patients discontinued treatment because of adverse events. FUNDING: GlaxoSmithKline.

Loss of B cells and their precursors is the most constant feature of GATA-2 deficiency in childhood myelodysplastic syndrome.

GATA-2 deficiency was recently described as common cause of overlapping syndromes of immunodeficiency, lymphedema, familiar myelodysplastic syndrome or acute myeloid leukemia. The aim of our study was to analyze bone marrow and peripheral blood samples of children with myelodysplastic syndrome or aplastic anemia to define prevalence of the GATA2 mutation and to assess whether mutations in GATA-2 transcription factor exhibit specific immunophenotypic features. The prevalence of a GATA2 mutation in a consecutively diagnosed cohort of children was 14% in advanced forms of myelodysplastic syndrome (refractory anemia with excess blasts, refractory anemia with excess blasts in transformation, and myelodysplasia-related acute myeloid leukemia), 17% in refractory cytopenia of childhood, and 0% in aplastic anemia. In GATA-2-deficient cases, we found the most profound B-cell lymphopenia, including its progenitors in blood and bone marrow, which correlated with significantly diminished intronRSS-Kde recombination excision circles in comparison to other myelodysplastic syndrome/aplastic anemia cases. The other typical features of GATA-2 deficiency (monocytopenia and natural killer cell lymphopenia) were less discriminative. In conclusion, we suggest screening for GATA2 mutations in pediatric myelodysplastic syndrome, preferentially in patients with impaired B-cell homeostasis in bone marrow and peripheral blood (low number of progenitors, intronRSS-Kde recombination excision circles and naïve cells).

Molecular Characterization of ß-Thalassemia in the Czech and Slovak Populations: Mediterranean, Asian and Unique Mutations.

ß-Thalassemia (ß-thal) is considered rare in Central Europe. As in other malaria-free regions, the presence of ß-thal in Central Europe reflects historical and recent immigration, and demographic changes that have influenced the genetic variability of the current populations living in this area. This study assesses the frequency and spectrum of mutations on the ß-globin gene in Czech and Slovak subjects with clinical symptoms of thalassemia. The results of the initial part of this research were published more than two decades ago; the aim of this study was to update these original reports. During the period from 2002 to 2015, 400 cases from Czech and Slovak hematological centers were analyzed. Twenty-nine ß-thal mutations, identified in 356 heterozygotes from 218 unrelated families, involve five unique mutations including a recently described insertion of a transposable L1 element into the ß-globin gene. One mutation described here is reported for the first time. Most of the mutations were of Mediterranean origin and accounted for 82.0% of cases. All but one case studied were heterozygous carriers, manifesting ß-thal minor, with rare exceptions represented by the rare (ß(0)) codons 46/47 (+G) (HBB: c.142_142dupG) mutation associated with an α-globin gene quadruplication and by dominantly inherited ß-thal with a more severe phenotype. One double heterozygous ß-thal patient was a recent immigrant from Moldavia. The list of δß-thal alleles (26 carriers, 16 families) contains Hb Lepore and two types of δß(0)-thal deletions. In the past, genetic drift and migration as well as recent immigrations were responsible for the introduction of Mediterranean alleles, while several mutations described in single families were of local origin.

Iron status in patients with pyruvate kinase deficiency: neonatal hyperferritinaemia associated with a novel frameshift deletion in the PKLR gene (p.Arg518fs), and low hepcidin to ferritin ratios.

Pyruvate kinase (PK) deficiency is an iron-loading anaemia characterized by chronic haemolysis, ineffective erythropoiesis and a requirement for blood transfusion in most cases. We studied 11 patients from 10 unrelated families and found nine different disease-causing PKLR mutations. Two of these mutations - the point mutation c.878A>T (p.Asp293Val) and the frameshift deletion c.1553delG (p.(Arg518Leufs*12)) - have not been previously described in the literature. This frameshift deletion was associated with an unusually severe phenotype involving neonatal hyperferritinaemia that is not typical of PK deficiency. No disease-causing mutations in genes associated with haemochromatosis could be found. Inappropriately low levels of hepcidin with respect to iron loading were detected in all PK-deficient patients with increased ferritin, confirming the predominant effect of accelerated erythropoiesis on hepcidin production. Although the levels of a putative hepcidin suppressor, growth differentiation factor-15, were increased in PK-deficient patients, no negative correlation with hepcidin was found. This result indicates the existence of another as-yet unidentified erythroid regulator of hepcidin synthesis in PK deficiency.