Myelodysplastic syndrome in children and adolescents

Childhood Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) in children is rare, accounting for < 5% of all childhood hematologic malignancies. With the advent of next-generation sequencing, the etiology of many childhood MDS (cMDS) cases has been elucidated with the finding of predisposing germline mutations in one-quarter to one-third of cases; somatic mutations have also been identified, indicating that cMDS is different than adult MDS. Herein, cMDS classification schema, clinical presentation, laboratory values, bone marrow histology, differential diagnostic considerations, and the recent molecular findings of cMDS are described.

A familial SAMD9 variant present in pediatric myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a rare pediatric diagnosis characterized by ineffective hematopoiesis with potential to evolve into acute myelogenous leukemia (AML). In this report, we describe a unique case of a 17-yr-old female with an aggressive course of MDS with excess blasts who was found to have monosomy 7 and a SAMD9 germline variant, which has not previously been associated with a MDS phenotype. This case of MDS was extremely rapidly progressing, showing resistance to chemotherapy and stem cell transplant, unfortunately resulting in patient death. It is imperative to further investigate this rare variant to aid in the future care of patients with this variant.

Myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a family of myeloid cancers with diverse genotypes and phenotypes characterized by ineffective haematopoiesis and risk of transformation to acute myeloid leukaemia (AML). Some epidemiological data indicate that MDS incidence is increasing in resource-rich regions but this is controversial. Most MDS cases are caused by randomly acquired somatic mutations. In some patients, the phenotype and/or genotype of MDS overlaps with that of bone marrow failure disorders such as aplastic anaemia, paroxysmal nocturnal haemoglobinuria (PNH) and AML. Prognostic systems, such as the revised International Prognostic Scoring System (IPSS-R), provide reasonably accurate predictions of survival at the population level. Therapeutic goals in individuals with lower-risk MDS include improving quality of life and minimizing erythrocyte and platelet transfusions. Therapeutic goals in people with higher-risk MDS include decreasing the risk of AML transformation and prolonging survival. Haematopoietic cell transplantation (HCT) can cure MDS, yet fewer than 10% of affected individuals receive this treatment. However, how, when and in which patients with HCT for MDS should be performed remains controversial, with some studies suggesting HCT is preferred in some individuals with higher-risk MDS. Advances in the understanding of MDS biology offer the prospect of new therapeutic approaches.

Discovery of MIRAGE syndrome

Since the first report in 2009, whole exome sequencing has become the most effective and efficient research tool in human genetics. MIRAGE syndrome is a novel single-gene disorder discovered through whole-exome sequencing for pediatric patients with adrenal insufficiency of unknown etiology, and is caused by de novo heterozygous variants in SAMD9. MIRAGE syndrome was initially discovered as a systemic disease affecting multiple systems, including hematopoietic, immune, endocrine, and gastrointestinal systems but later studies revealed a subset of patients with myelodysplastic syndrome as the sole manifestation. In addition, pathogenic variants in SAMD9L, a paralog gene of SAMD9, were reported to cause an inherited disorder of the hematopoietic system and central nervous system, called ataxia-pancytopenia syndrome. This article reviews the history of MIRAGE syndrome from its discovery to the proposal of SAMD9/SAMD9L syndromes, and discusses directions for future research.

Pediatric MDS and bone marrow failure-associated germline mutations in SAMD9 and SAMD9L impair multiple pathways in primary hematopoietic cells

Pediatric myelodysplastic syndromes (MDS) are a heterogeneous disease group associated with impaired hematopoiesis, bone marrow hypocellularity, and frequently have deletions involving chromosome 7 (monosomy 7). We and others recently identified heterozygous germline mutations in SAMD9 and SAMD9L in children with monosomy 7 and MDS. We previously demonstrated an antiproliferative effect of these gene products in non-hematopoietic cells, which was exacerbated by their patient-associated mutations. Here, we used a lentiviral overexpression approach to assess the functional impact and underlying cellular processes of wild-type and mutant SAMD9 or SAMD9L in primary mouse or human hematopoietic stem and progenitor cells (HSPC). Using a combination of protein interactome analyses, transcriptional profiling, and functional validation, we show that SAMD9 and SAMD9L are multifunctional proteins that cause profound alterations in cell cycle, cell proliferation, and protein translation in HSPCs. Importantly, our molecular and functional studies also demonstrated that expression of these genes and their mutations leads to a cellular environment that promotes DNA damage repair defects and ultimately apoptosis in hematopoietic cells. This study provides novel functional insights into SAMD9 and SAMD9L and how their mutations can potentially alter hematopoietic function and lead to bone marrow hypocellularity, a hallmark of pediatric MDS.

A Case of Myelofibrosis and Myelodysplasia Identified Following Exposure to Isotretinoin

A 15-year-old male individual treated with isotretinoin for acne vulgaris presented with persistent pancytopenia and circulating myeloblasts after discontinuation of the drug. Marrow assessment revealed myelofibrosis (MF) and myeloblasts exhibiting monosomy 7, diagnostic of myelodysplastic syndrome (MDS). Although a popular website seems to associate isotretinoin with MF, no published cases of MF or MDS attributable to this drug were identified. Although we expect that he would eventually have developed MDS and MF, this patient was perhaps identified sooner due to cytopenias accelerated by isotretinoin. This case illustrates that patients exhibiting cytopenias persisting following isotretinoin therapy merit evaluation for underlying hematopoietic disorders.

A Prospective Study of Hematologic Complications and Long-Term Survival of Italian Patients Affected by Shwachman-Diamond Syndrome

OBJECTIVE

To describe the hematologic outcome and long-term survival of patients enrolled in the Shwachman-Diamond syndrome Italian Registry.

STUDY DESIGN

A retrospective and prospective study of patients recorded in the Shwachman-Diamond syndrome Italian Registry.

RESULTS

The study population included 121 patients, 69 males and 52 females, diagnosed between 1999 and 2018. All patients had the clinical diagnosis confirmed by mutational analysis on the SBDS gene. During the study period, the incidence of SDS was 1 in 153 000 births. The median age of patients with SDS at diagnosis was 1.3 years (range, 0-35.6 years). At the first hematologic assessment, severe neutropenia was present in 25.8%, thrombocytopenia in 25.5%, and anemia in 4.6% of patients. A normal karyotype was found in 40 of 79 patients, assessed whereas the most frequent cytogenetic abnormalities were isochromosome 7 and interstitial deletion of the long arm of chromosome 20. The cumulative incidence of severe neutropenia, thrombocytopenia, and anemia at 30 years of age were 59.9%, 66.8%, and 20.2%, respectively. The 20-year cumulative incidence of myelodysplastic syndrome/leukemia and of bone marrow failure/severe cytopenia was 9.8% and 9.9%, respectively. Fifteen of 121 patients (12.4%) underwent allogeneic stem cell transplantation. Fifteen patients (12.4%) died; the probability of overall survival at 10 and 20 years was 95.7% and 87.4%, respectively.

CONCLUSIONS

Despite an improvement in survival, hematologic complications still cause death in patients with SDS. Further studies are needed to optimize type and modality of hematopoietic stem cell transplantation and to assess the long-term outcome in nontransplanted patients.

An uncommon t(9;11)(p24;q22) with monoallelic loss of ATM and KMT2A genes in a child with myelodysplastic syndrome/acute myeloid leukemia who evolved from Fanconi anemia

BACKGROUND

Myelodysplastic syndrome (MDS) is rare in the pediatric age group and it may be associated with inheritable bone marrow failure (BMF) such as Fanconi anemia (FA). FA is a rare multi-system genetic disorder, characterized by congenital malformations and progressive BMF. Patients with FA usually present chromosomal aberrations when evolving to MDS or acute myeloid leukemia (AML). Thus, the cytogenetic studies in the bone marrow (BM) of these patients have an important role in the therapeutic decision, mainly in the indication for hematopoietic stem cell transplantation (HSCT). The most frequent chromosomal alterations in the BM of FA patients are gains of the chromosomal regions 1q and 3q, and partial or complete loss of chromosome 7. However, the significance and the predictive value of such clonal alterations, with respect to malignant progress, are not fully understood and data from molecular cytogenetic studies are very limited.

CASE PRESENTATION

A five-year-old boy presented recurrent infections and persistent anemia. The BM biopsy revealed hypocellularity. G-banding was performed on BM cells and showed a normal karyotype. The physical examination showed to be characteristic of FA, being the diagnosis confirmed by DEB test. Five years later, even with supportive treatment, the patient presented severe hypocellularity and BM evolution revealing megakaryocyte dysplasia, intense dyserythropoiesis, and 11% myeloblasts. G-banded analysis showed an abnormal karyotype involving a der(9)t(9;11)(p24;q?22). The FISH analysis showed the monoallelic loss of ATM and KMT2A genes. At this moment the diagnosis was MDS, refractory anemia with excess of blasts (RAEB). Allogeneic HSCT was indicated early in the diagnosis, but no donor was found. Decitabine treatment was initiated and well tolerated, although progression to AML occurred 3 months later. Chemotherapy induction was initiated, but there was no response. The patient died due to disease progression and infection complications.

CONCLUSIONS

Molecular cytogenetic analysis showed a yet unreported der(9)t(9;11)(p24;q?22),der(11)t(9;11)(p24;q?22) during the evolution from FA to MDS/AML. The FISH technique was important allowing the identification at the molecular level of the monoallelic deletion involving the KMT2A and ATM genes. Our results suggest that this chromosomal alteration conferred a poor prognosis, being associated with a rapid leukemic transformation and a poor treatment response.

Diagnostics and Prognostication of Myelodysplastic Syndromes

MDS are a heterogeneous and complex group of clonal hematological neoplasms arising from a hematopoietic stem cell, and characterized by ineffective hematopoiesis, resulting in increased apoptosis in the bone marrow and peripheral cytopenia, which involves one or more lineages. Epigenetic changes are reported as ‘founder’ mutations in the case of MDS. Its incidence in the general population has been reported as five new MDS diagnoses per 100,000 people. It affects men more frequently than it does women, and its incidence increases with age. The diagnostic classification, now in use, is the one of the World Health Organization, revised in August 2016. It recognizes six distinct entities in addition to a provisional entity of childhood. In most of the cases, diagnosis is based on the morphologic quantitative and qualitative evaluation of the peripheral blood and bone marrow using basic hematological techniques. Bone marrow biopsy and flow cytometric immunophenotyping also offer support for further diagnostic elucidation, while cytogenetics and molecular genetics are presently fully integrated into prognostication, treatment processes, and decision-making.

Gain-of-function SAMD9L mutations cause a syndrome of cytopenia, immunodeficiency, MDS, and neurological symptoms

Several monogenic causes of familial myelodysplastic syndrome (MDS) have recently been identified. We studied 2 families with cytopenia, predisposition to MDS with chromosome 7 aberrations, immunodeficiency, and progressive cerebellar dysfunction. Genetic studies uncovered heterozygous missense mutations in SAMD9L, a tumor suppressor gene located on chromosome arm 7q. Consistent with a gain-of-function effect, ectopic expression of the 2 identified SAMD9L mutants decreased cell proliferation relative to wild-type protein. Of the 10 individuals identified who were heterozygous for either SAMD9L mutation, 3 developed MDS upon loss of the mutated SAMD9L allele following intracellular infections associated with myeloid, B-, and natural killer (NK)-cell deficiency. Five other individuals, 3 with spontaneously resolved cytopenic episodes in infancy, harbored hematopoietic revertant mosaicism by uniparental disomy of 7q, with loss of the mutated allele or additional in cisSAMD9L truncating mutations. Examination of 1 individual indicated that somatic reversions were postnatally selected. Somatic mutations were tracked to CD34⁺ hematopoietic progenitor cell populations, being further enriched in B and NK cells. Stimulation of these cell types with interferon (IFN)-α or IFN-γ induced SAMD9L expression. Clinically, revertant mosaicism was associated with milder disease, yet neurological manifestations persisted in 3 individuals. Two carriers also harbored a rare, in trans germ line SAMD9L missense loss-of-function variant, potentially counteracting the SAMD9L mutation. Our results demonstrate that gain-of-function mutations in the tumor suppressor SAMD9L cause cytopenia, immunodeficiency, variable neurological presentation, and predisposition to MDS with -7/del(7q), whereas hematopoietic revertant mosaicism commonly ameliorated clinical manifestations. The findings suggest a role for SAMD9L in regulating IFN-driven, demand-adapted hematopoiesis.

Are micromegakaryocytes specific for refractory cytopenia of childhood (RCC)? A study of 38 pediatric patients with thrombocytopenia unrelated to RCC

BACKGROUND

Micromegakaryocytes (microMKs) are considered the most reliable dysplastic feature for myelodysplastic syndrome (MDS), particularly refractory cytopenia of childhood (RCC); there is no minimal threshold for the diagnosis of RCC. Since most RCC patients present with thrombocytopenia, the presence of microMKs should raise concern for MDS/RCC. This study attempted to investigate the prevalence of microMKs and associated marrow fibrosis in patients with thrombocytopenia unrelated to MDS/RCC and the need for establishing a threshold for microMKs for the diagnosis of MDS/RCC.

DESIGN

Bone marrow biopsies of pediatric patients with thrombocytopenia unrelated to RCC were examined for microMKs and fibrosis by CD61 immunohistochemical and reticulin stains respectively.

RESULT

Thirty eight patients (1-18 years old) were included: 33 immune thrombocytopenia (ITP), 3 chronic thrombocytopenia, and 2 inherited macrothrombocytopenia. Fourteen cases (37%) had microMKs; four cases showed increased marrow fibrosis associated with microMKs (two had ITP and two had macrothrombocytopenia). All patients are alive and none developed MDS (follow up: 3months to 4 years).

CONCLUSION

MicroMKs can be seen in pediatric patients with thrombocytopenia unrelated to RCC. Hence the mere presence of microMKs is insufficient for the diagnosis of RCC in the pediatric population, and a quantitative threshold needs to be established.

SAMD9 mutations cause a novel multisystem disorder, MIRAGE syndrome, and are associated with loss of chromosome 7

Adrenal hypoplasia is a rare, life-threatening congenital disorder. Here we define a new form of syndromic adrenal hypoplasia, which we propose to term MIRAGE (myelodysplasia, infection, restriction of growth, adrenal hypoplasia, genital phenotypes, and enteropathy) syndrome. By exome sequencing and follow-up studies, we identified 11 patients with adrenal hypoplasia and common extra-adrenal features harboring mutations in SAMD9. Expression of the wild-type SAMD9 protein, a facilitator of endosome fusion, caused mild growth restriction in cultured cells, whereas expression of mutants caused profound growth inhibition. Patient-derived fibroblasts had restricted growth, decreased plasma membrane EGFR expression, increased size of early endosomes, and intracellular accumulation of giant vesicles carrying a late endosome marker. Of interest, two patients developed myelodysplasitc syndrome (MDS) that was accompanied by loss of the chromosome 7 carrying the SAMD9 mutation. Considering the potent growth-restricting activity of the SAMD9 mutants, the loss of chromosome 7 presumably occurred as an adaptation to the growth-restricting condition.

Myelodysplastic Syndromes: Diagnosis and Treatment

In the past few years, new biological insights into the myelodysplastic syndromes (MDS) resulting from molecular genetic analysis have improved pathologic understanding, but treatment advances have not kept pace. More than 40 genes are now known to be recurrently mutated in MDS. However, because most of these genes encode spliceosome components, chromatic remodeling factors, epigenetic pattern modulators, or transcription factors rather than more easily inhibited activated tyrosine kinases, there are as of yet few narrowly targeted therapies available for MDS. Three drugs--azacitidine, decitabine, and lenalidomide--were approved by the US Food and Drug Administration for MDS indications a decade ago, and these agents can improve hematopoiesis, delay disease progression, and improve survival and quality of life for a subset of patients. However, only a few patients with MDS respond to these agents, and their benefit is temporary. The only potentially curative therapy for MDS is allogeneic hematopoietic stem cell transplant, but owing to the advanced age of many patients with MDS and the frequency of serious comorbid conditions, less than 10% of patients currently undergo stem cell transplant. This narrative review summarizes the current understanding of MDS and treatment options for these challenging disorders.

The impact of category, cytopathology and cytogenetics on development and progression of clonal and malignant myeloid transformation in inherited bone marrow failure syndromes

Inherited bone marrow failure syndromes are a group of rare, heterogeneous genetic disorders with a risk of clonal and malignant myeloid transformation including clonal marrow cytogenetic abnormalities, myelodysplastic syndrome and acute myeloid leukemia. The clinical characteristics, risk classification, prognostic factors and outcome of clonal and malignant myeloid transformation associated with inherited bone marrow failure syndromes are largely unknown. The aims of this study were to determine the impact of category, cytopathology and cytogenetics, the three components of the "Category Cytology Cytogenetics" classification of pediatric myelodysplastic syndrome, on the outcome of clonal and malignant myeloid transformation associated with inherited bone marrow failure. We used data from the Canadian Inherited Marrow Failure Registry. Among 327 patients with inherited bone marrow failure syndrome enrolled in the registry, the estimated risk of clonal and malignant myeloid transformation by the age of 18 years was 37%. The risk of clonal and malignant myeloid transformation varied according to the type of inherited bone marrow failure syndrome but was highest in Fanconi anemia. The development of clonal and malignant myeloid transformation significantly affected overall survival. Mortality varied based on cytopathological group. The largest group of patients had refractory cytopenia. Clonal marrow cytogenetic abnormalities were identified in 87% of patients with clonal and malignant myeloid transformation, and different cytogenetic groups had different impacts on disease progression. We conclude that category, cytopathology and cytogenetics in cases of clonal and malignant myeloid transformation associated with inherited bone marrow failure syndromes have an important impact on outcome and that the classification of such cases should incorporate these factors.

Cytogenetic as an important tool for diagnosis and prognosis for patients with hypocellular primary myelodysplastic syndrome

We analyzed cytogenetically 105 patients with hypocellular primary MDS and their clinical implications. The main chromosomal abnormalities found were del(5q)/−5, del(6q)/+6, del(7q)/−7, del(11q), and del(17p). Pediatric patients had a higher frequency of abnormal karyotypes compared with adult patients (P < 0,05). From our patients, 18% showed evolution of the disease. The chromosomal abnormalities presented in the diagnosis of patients who evolved to AML included numerical (−7, +8) and structural del(6q), del(7q), i(7q), t(7;9), i(9q), and del(11q) abnormalities and complex karyotypes. Although the frequency of evolution from hypocellular MDS to AML is low, our results suggest that some chromosomal alterations may play a critical role during this process. We applied the IPSS in our patients because this score system has been proved to be useful for predicting evolution of disease. When we considered the patients according to group 1 (intermediate-1) and group 2 (intermediate-2 and high risk), we showed that group 2 had a high association with respect to the frequency of abnormal karyotypes (P < 0,0001), evolution of disease (P < 0,0001), and mortality (P < 0,001). In fact, the cytogenetic analysis for patients with hypocellular primary MDS is an important tool for diagnosis, prognosis, in clinical decision-making and in follow-up.

Pediatric myelodysplastic syndromes: they do exist!

One of the most common hematologic malignancies in adults, myelodysplastic syndrome (MDS) is a heterogenous group of clonal disorders characterized by peripheral cytopenia(s) and normal or hypercellular bone marrow with dysplasia in ≥1 blood cell lineages. MDS frequently evolves to secondary acute myeloid leukemia with poor prognosis. Although uncommon among pediatric hematologic malignancies, both de novo and secondary MDS occur in children and may be the first presentation of an inherited bone marrow failure syndrome. Unlike its adult counterpart, pediatric MDS is more frequently associated with hypocellular bone marrow and monosomy 7. Refractory cytopenia is more typical than refractory anemia, as seen in the elderly. Its recognition and management can be quite challenging and requires the expertise of an experienced hematopathologist. In this review, we describe the epidemiology, genetics, and clinical spectrum of pediatric MDS along with its diagnostic and therapeutic challenges. We also compare and contrast pediatric and adult MDS.

Myelodysplastic syndrome with pulmonary tumor thrombotic microangiopathy in an 11-year-old male patient

Myelodysplastic syndrome (MDS) and pulmonary tumor thrombotic microangiopathy (PTTM) are independently rare in the pediatric population. This report describes an 11-year-old male patient who initially presented with respiratory distress and cardiovascular collapse. A large left main pulmonary artery embolus and multiple, smaller pulmonary thromboemboli were widely dispersed throughout both lungs. Despite aggressive supportive care, he died within seven hours of admission. A complete postmortem examination was performed, leading to the diagnoses of primary MDS and microthrombi in the lungs, including the characteristic fibroproliferative lesions seen in PTTM. Individually, both conditions are extremely uncommon, and therefore the coincidence of these 2 conditions in a child is singularly unique.

Acquired aplastic anemia in children

This article provides a practice-based and concise review of the etiology, diagnosis, and management of acquired aplastic anemia in children. Bone marrow transplantation, immunosuppressive therapy, and supportive care are discussed in detail. The aim is to provide the clinician with a better understanding of the disease and to offer guidelines for the management of children with this uncommon yet serious disorder.

Childhood myelodysplastic syndrome

Myelodysplastic syndrome (MDS) comprises of a heterogeneous group of bone marrow disorders resulting from a clonal stem cell defect characterised by cytopenias despite a relatively hypercellular marrow, ineffective hematopoiesis, morphological dysplasia in the marrow elements, no response to hematinics such as iron, B12 or folic acid and risk of progression to leukemia. Myelodysplastic syndrome in childhood is extremely rare and accounts for less than 5% of all hematopoietic neoplasms in children below the age of 14 y. The primary MDS in children, also known as de novo MDS differs from secondary MDS which generally follows congenital or acquired bone marrow (BM) failure syndromes as well as from therapy related MDS, commonly resulting from cytotoxic therapy. MDS associated with Down syndrome which accounts for approximately one-fourth of cases of childhood MDS is now considered a unique biologic entity synonymous with Down syndrome-related myeloid leukemia and is biologically distinct from other cases of childhood MDS. Refractory cytopenia of childhood (RCC) is the commonest type of MDS. Genetic changes predisposing to MDS in childhood remain largely obscure. Monosomy 7 is by-far the commonest cytogenetic abnormality associated with childhood MDS; however most cases of RCC show a normal karyotype. Complex cytogenetic abnormalities and trisomy 8 and trisomy 21 are also occasionally observed. The most effective and curative treatment is Hematopoietic stem cell transplantation and this is particularly effective in children with the monosomy 7 genetic defect as well as those displaying complex karyotype abnormalities provided it is instituted early in the course of the disease.

Early hematopoietic stem cell transplant is associated with favorable outcomes in children with MDS

BACKGROUND

Although hematopoietic stem cell transplantation (HSCT) is the treatment of choice for childhood myelodysplastic syndrome (MDS), there is no consensus regarding patient or disease characteristics that predict outcomes.

PROCEDURE

We reviewed 37 consecutive pediatric MDS patients who received myeloablative HSCT between 1990 and 2010 at a single center.

RESULTS

Twenty had primary MDS and 17 had secondary MDS. Diagnostic cytogenetics included monosomy 7 (n = 21), trisomy 8 (n = 7) or normal/other (n = 8). According to the modified WHO MDS classification, thirty had refractory cytopenia and seven had refractory anemia with excess blasts. IPSS scores were: low risk (n = 1), intermediate-1 (n = 15), and intermediate-2 (n = 21). OS and DFS at 10 years in the entire cohort was 53% and 45%. Relapse at 10 years was 26% and 1 year TRM was 25%. In multivariate analysis, factors associated with improved 3 years DFS were not receiving pre-HSCT chemotherapy (RR = 0.30, 95% CI 0.10-0.88; P = 0.03) and a shorter interval (<140 days) from time of diagnosis to transplant (RR = 0.27, 95% CI 0.09-0.80; P = 0.02). Three years DFS in patients who did not receive pre-HSCT chemotherapy and those who had a shorter interval to transplant (n = 16) was 80%.

CONCLUSION

These results suggest that children with MDS should be referred for allogeneic HSCT soon after diagnosis and that pre-HSCT chemotherapy does not appear to improve outcomes.

[Transformation of myelodysplastic syndrome to acute lymphoblastic leukemia: 2 new cases]

Myelodysplastic syndromes (MDS) are clonal disorders of hematopoietic stem cells, with a variable risk of transformation to acute myeloid leukemia. Progression into acute lymphoblastic leukemia (ALL) is an extremely rare event, with very few cases published in children. In this report, we describe two cases of myelodysplastic syndromes that progressed to ALL. Moreover, we review previously reported cases of MDS transformation to acute lymphoblastic leukemia in the pediatric population whose prognosis seems to be similar to that for adults.

New recurrent chromosome change in pediatric therapy-related myelodysplastic syndrome: unbalanced translocation 1/6 with cryptic duplication of short arm of chromosome 6

The incidence of therapy-related myelodysplastic syndrome (t-MDS) in pediatric patients is increasing in parallel with the more successful management of the primary tumor, but scant information is available on clinical and cytogenetic characteristics. We report here two children affected by t-MDS after chemo/radiotherapy for a primary solid tumor, both with an unbalanced translocation 1/6 in their bone marrow. Characterization by array comparative genomic hybridization of the imbalances showed an almost identical pattern: almost complete trisomy of the long arm of chromosome 1, and a terminal deletion and interstitial duplication of the short arm of chromosome 6. The gain of chromosome 6 short arm encompasses regions already highlighted as possibly relevant for t-MDS in adults, and we suggest that the unbalanced translocation reported here be considered a new recurrent, non-random chromosomal abnormality in pediatric patients with t-MDS.

Classification of and risk factors for hematologic complications in a French national cohort of 102 patients with Shwachman-Diamond syndrome

BACKGROUND

Patients with the Shwachman-Diamond syndrome often develop hematologic complications. No risk factors for these complications have so far been identified. The aim of this study was to classify the hematologic complications occurring in patients with Shwachman-Diamond syndrome and to investigate the risk factors for these complications.

DESIGN AND METHODS

One hundred and two patients with Shwachman-Diamond syndrome, with a median follow-up of 11.6 years, were studied. Major hematologic complications were considered in the case of definitive severe cytopenia (i.e. anemia <7 g/dL or thrombocytopenia <20 × 10(9)/L), classified as malignant (myelodysplasia/leukemia) according to the 2008 World Health Organization classification or as non-malignant.

RESULTS

Severe cytopenia was observed in 21 patients and classified as malignant severe cytopenia (n=9), non-malignant severe cytopenia (n=9) and malignant severe cytopenia preceded by non-malignant severe cytopenia (n=3). The 20-year cumulative risk of severe cytopenia was 24.3% (95% confidence interval: 15.3%-38.5%). Young age at first symptoms (<3 months) and low hematologic parameters both at diagnosis of the disease and during the follow-up were associated with severe hematologic complications (P<0.001). Fifteen novel SBDS mutations were identified. Genotype analysis showed no discernible prognostic value. CONCLUSIONS Patients with Shwachman-Diamond syndrome with very early symptoms or cytopenia at diagnosis (even mild anemia or thrombocytopenia) should be considered at a high risk of severe hematologic complications, malignant or non-malignant. Transient severe cytopenia or an indolent cytogenetic clone had no deleterious value.

Allogeneic hematopoetic stem cell transplantation in pediatric myelodysplastic syndromes: improved outcomes for de novo disease

We report 23 consecutive pediatric patients with MDS who received allogeneic HSCT on IRB approved protocols between 1992 and 2009 at Children's Memorial Hospital (Chicago, IL). Nine patients had de novo MDS, whereas 14 patients had treatment-related MDS. All patients had a documented cytogenetic abnormality, and monosomy 7/7q- was seen in 12 patients (52%). Fourteen of 23 patients received a myeloablative conditioning regimen; RIC regimens were used for the remaining nine. Five patients relapsed post-transplant, including four patients who received RIC transplant and four patients with treatment-related MDS. For the entire group, estimated five-yr RFS and OS were 47% and 50%, respectively. Treatment-related MDS was associated with decreased RFS in comparison with de novo MDS (33% vs. 70%, p = 0.05). Five-year OS rates reached 80% for those with de novo MDS. RIC regimens were associated with decreased three-yr RFS in comparison with myeloablative regimens (22% vs. 68%, p = 0.02). There was no correlation of survival with blast count at diagnosis, IPSS score, cytogenetic abnormality, donor type, or HLA match. Larger series are needed to confirm prognostic factors so that higher-risk patients can be targeted with novel approaches.

Epigenetic alterations of p15(INK4B) and p16(INK4A) genes in pediatric primary myelodysplastic syndrome

We studied the methylation status of the p15(INK4B) and p16(INK4A) genes in 47 pediatric patients with primary MDS, its correlation with subtype, and the role of p15(INK4B) and p16(INK4A) in the evolution of MDS toward AML. Aberrant methylation of the p15(INK4B) gene was detected in 15 of 47 patients (32%), whereas only four patients demonstrated methylation of the p16(INK4A) gene (8%). The frequency of p15(INK4B) methylation was significantly higher in RAEB and RAEB-t subtypes (p<0.003). Aberrant methylation of the p16(INK4A) gene was also more frequent in the subtypes that characterize advanced stages of the disease (p<0.05). Evolution of disease was verified in 17 (36%) of the 47 patients. The association of p15(INK4B) and p16(INK4A) methylation status with evolution of disease was clearly significant (p<0.008 and p<0.05, respectively). These results suggest that methylation of the p15(INK4B) and p16(INK4A) genes is an epigenetic biomarker of pediatric disease evolution.

Classification of childhood aplastic anemia and myelodysplastic syndrome

Hypoplastic BM disorders in children and adolescents comprise a broad spectrum of disorders. Acquired severe aplastic anemia (SAA), refractory cytopenia of childhood (RCC), a subtype of myelodysplastic syndrome (MDS), and inherited BM failure (IBMF) disorders are the main and most difficult hematological differential diagnoses. Whereas IBMF disorders can often be diagnosed by their clinical features and/or underlying genetic aberrations, the morphological distinction between SAA and hypocellular RCC has been controversial. The histopathological pattern of RCC consists of islands of immature erythroid precursors accompanied by sparsely distributed granulocytic cells. Megakaryocytes are significantly decreased or absent and, rarely, micromegakaryocytes are detected on immunohistochemistry. Because fatty tissue between areas of hematopoiesis can mimic SAA, 2 biopsies are recommended to facilitate the detection of representative BM spaces. Recent data indicate that the response to immunosuppressive therapy is inferior in RCC compared with SAA. Furthermore, approaches to allogeneic hematopoietic transplantation differ. Controlled prospective clinical studies in patients with hypoplastic BM failure disorders will require comprehensive guidelines for diagnosing SAA, RCC, and the different IBMF disorders.

Clonal heterogeneity in childhood myelodysplastic syndromes--challenge for the detection of chromosomal imbalances by array-CGH

To evaluate whether copy number alterations (CNAs) are present that may contribute to disease development and/or progression of childhood myelodysplastic syndromes (MDS), 36 pediatric MDS patients were analyzed using array-based comparative genome hybridization (aCGH). In addition to monosomy 7, the most frequent chromosome aberration in childhood MDS, novel recurrent CNAs were detected. They included a loss of 3p14.3-p12.3, which contains the putative tumor suppressor gene FHIT, a loss of 7p21.3-p15.3, a loss of 9q33.3-q34.3 (D184) and microdeletions in 17p11.2, 6q23 containing MYB, and 17p13 containing TP53. In this small patient cohort, patients without CNA, patients with monosomy 7 only and patients with one CNA in addition to monosomy 7 did not differ in their survival. As expected, all patients with complex karyotypes, including two patients with deletions of TP53, died. A challenge inherent to aCGH analysis of MDS is the low percentage of tumor cells. We evaluated several approaches to overcome this limitation. Genomic profiles from isolated granulocytes were of higher quality than those from bone marrow mononuclear cells. Decreased breakpoint calling stringency increased recognition of CNAs present in small clonal populations. However, further analysis using a custom-designed array showed that these CNAs often did not confirm the findings from 244k arrays. In contrast, constitutional CNVs were reliably detected on both arrays. Moreover, aCGH on amplified DNA from distinct myeloid clusters is a new approach to determine CNAs in small subpopulations. Our results clearly emphasize the need to verify array-CGH results by independent methods like FISH or quantitative PCR.

Diagnosis of myelodysplastic syndrome among a cohort of 119 patients with fanconi anemia: morphologic and cytogenetic characteristics

Predisposition to myelodysplastic syndrome (MDS) and acute leukemia is a hallmark of Fanconi anemia (FA). Morphologic criteria for MDS in FA are not well established, nor is the significance of clonal chromosomal abnormalities. We reviewed bone marrow samples of 119 FA patients: 23 had MDS, with the most common subtype refractory cytopenia with multilineage dysplasia. The presence of MDS was highly correlated with the presence of clonal abnormalities. Neutrophil dysplasia and increased blasts were always associated with the presence of a clone, in contrast with dyserythropoiesis. The most frequent clones had gains of 1q and 3q and/or loss of 7. Karyotype complexity also correlated with MDS. One third of patients with 3q as a sole abnormality had no MDS; patients with 3q and an additional abnormality all had MDS. The data provide a rationale for integrating cytogenetic findings with independently evaluated morphologic findings for monitoring bone marrow status in FA.

Diagnostic criteria to distinguish hypocellular acute myeloid leukemia from hypocellular myelodysplastic syndromes and aplastic anemia: recommendations for a standardized approach

Members of the French-American-British Cooperative Leukemia Working Group met to review cases of aplastic anemia, hypocellular myelodysplastic syndrome and hypocellular acute myeloid leukemia. Criteria were proposed and modified following three workshops. Additional input was obtained from another hematopathologist with a special interest in bone marrow histology and immunohistochemistry. Guidelines were recommended based on the workshop results as well as additional studies including selective immunohistochemistry, flow cytometry and cytogenetics.

Childhood leukemia in relation to radio frequency electromagnetic fields in the vicinity of TV and radio broadcast transmitters

A case-control study of radio frequency electromagnetic fields (RF-EMFs) and childhood leukemia was conducted in West Germany. The study region included municipalities near high-power radio and TV broadcast towers, including 16 amplitude-modulated and 8 frequency-modulated transmitters. Cases were aged 0-14 years, were diagnosed with leukemia between 1984 and 2003, and were registered at the German Childhood Cancer Registry. Three age-, gender-, and transmitter-area-matched controls per case were drawn randomly from population registries. The analysis included 1,959 cases and 5,848 controls. Individual exposure to RF-EMFs 1 year before diagnosis was estimated with a field strength prediction program. Considering total RF-EMFs, the odds ratio derived from conditional logistic regression analysis for all types of leukemia was 0.86 (95% confidence interval: 0.67, 1.11) when upper (>or=95%/0.701 V/m) and lower (<90%/0.504 V/m) quantiles of the RF-EMF distribution were compared. An analysis of amplitude-modulated and frequency-modulated transmitters separately did not show increased risks of leukemia. The odds ratio for all types of leukemia was 1.04 (95% confidence interval: 0.65, 1.67) among children living within 2 km of the nearest broadcast transmitter compared with those living at a distance of 10-<15 km. The data did not show any elevated risks of childhood leukemia associated with RF-EMFs.