Exploring the Pathogenesis of Down Syndrome-Related Myeloproliferative Disorders Using iPSCs

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 868-868
Author(s):  
Nishinaka Yoko ◽  
Akira Niwa ◽  
Mitsujiro Osawa ◽  
Akira Watanabe ◽  
Tatsutoshi Nakahata ◽  
...  
Keyword(s):  
Down Syndrome ◽  
B Lymphocytes ◽  
Trisomy 21 ◽  
Morphological Difference ◽  
Chromosome 21 ◽  
Fish Analysis ◽  
Transcription Activator ◽  
Differentiation Potential ◽  
Exon 2 ◽  
Gata1 Mutation

Abstract Down syndrome (DS) is a congenital syndrome due to the trisomy of chromosome 21. Transient myeloproliferative disorder (TMD) is its hematopoietic complication, affecting approximately 10% of DS-neonates. TMD is characterized by transient abnormal proliferation of blastic cells, and importantly, all TMD blasts bear mutations in GATA1 gene. Although TMD usually resolves spontaneously within 3 months after birth, twenty to thirty percent of TMD patients develop acute megakaryoblastic leukemia (AMKL) within several years afterward. This leukemogenic transition is considered as a good model for multi-step tumorigenesis. According to this putative multi-step model, the first hit should be additional chromosome 21, the second one is mutations on GATA1 gene which is requisite to the onset of TMD, and the “unknown” third hits are required for the progression into AMKL. However, it is still unclear that 1) how GATA1 mutation promotes TMD development, 2) what kinds of third hit are required for the onset of AMKL, and 3) why GATA1-mutated progenitors prevails during embryonic hematopoiesis only in trisomy 21 patients? In order to address these issues, a strictly controlled isogenic cell panels that can reproduce human emboryonic hematopoietic development is needed. Human induced pluripotent stem cells (iPSCs) derived from DS patients are a promising platform for this, but so far there is no report regarding GATA1-mutated TMD-associated iPSCs. Therefore, we set out to establish an iPSC panel that covers each genomic status of chromosome 21 and GATA1 gene. For this, we established both GATA1 mutant and wildtype clones from both trisomy 21 and disomy 21 clones. And we also established TMD patient derived iPSCs. First, we established isogenic iPSCs derived from EB virus immortalized B-lymphocytes of 2 mosaic DS patients. Frequency of trisomy 21 cells evaluated by FISH analysis and G-banding were 93% and 94% for each patient. We reprogrammed these cells by introducing 5 episomal vectors, pCE-hOCT3/4, pCE-hSK, pCE-hUL, pCE-mp53DD and pCXB-EBNA1, under feeder free condition. We genotyped each iPSC clones by digital-PCR analysis and found that the frequency of trisomy iPSC clones were comparable to that of trisomy cells in original EBV immortalized B-lymphocytes. There is no morphological difference between disomy and trisomy iPSC clones in both patients. We next introduced disease-associated GATA1 mutation into established isogenic trisomy and disomy iPS clones using transcription activator-like effector nuclease (TALEN) technology. We introduced a frameshift mutation in exon 2, which causes premature termination of the full-length transcript originated from 1st ATG and exclusively produces the shorter isoform of GATA1 (GATA1s) transcribed from 2nd ATG. Next, we obtained peripheral blood mononuclear cells (PBMCs) from a TMD patient in order to establish TMD-blast-derived iPSCs. Eighty-nine percent of nuclear cells in the PBMC fraction was CD117+CD45+ blastic cells, whereas only 5.6% were non-blast cells including CD3 positive T-lymphocytes, CD11b positive myeloid lineage cells and CD19 positive B-lymphocytes. The CD117+ cells showed TMD/AMKL blast-like appearance such as coarse choromatin pattern with nucleolus and bleb-like structures. We sorted out CD45+CD117+ blastic cells and CD45+CD117- non-blastic cells and successfully established iPSC clones from both populations. In conclusion, we successfully established a comprehensive panel of iPSC clones for evaluating the hematopoietic consequence associated with the GATA1 genotype and the ploidy of chromosome 21. We are currently evaluating hematopoietic differentiation potential of each clone and exploring the underlying pathophysiology of TMD/AMKL by using this platform. We believe that comprehensive understanding of TMD and AMKL pathogenesis provides a fruitful insight into our understanding of human leukemogenesis. Disclosures No relevant conflicts of interest to declare.

GATA1 Mutations in Clonal Disorders of Children with and without Down Syndrome.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4314-4314
Author(s):  
Isis Q. Magalhaes ◽  
Alessandra Splendore ◽  
Mariana Emerenciano ◽  
Iris Ferrari ◽  
Maria S. Pombo-de-Oliveira
Keyword(s):  
Down Syndrome ◽  
Trisomy 21 ◽  
Genomic Dna ◽  
Stop Codon ◽  
Pediatric Population ◽  
Premature Stop Codon ◽  
Genetic Changes ◽  
Exon 2 ◽  
Gata1 Mutation ◽  
Proliferative Advantage

Abstract Down Syndrome (DS) children are 10–20 times folder likely to develop acute leukemia (AL) within the first four years of life compared to general pediatric population. Recently acquired somatic mutations in GATA1 gene on chromosome X have been described in most cases of DS AML and congenital TMD of DS carry the same type of mutations in exon 2 of GATA1. Here we report the preliminary results of GATA1 mutation in AL with and without DS children. The aim of this study is to provide insights in the relationships of GATA1 mutations and trisomy 21 in leukemogenesis process. GATA1 mutations were assayed in genomic DNA in 34 children with DS and AL, 2 with transient myeloproliferative disorder (TMD), 3 with myelodisplastic syndrome. Sequential sample including 2 pre-diagnosis in neonate period and 1 year before diagnosis were available in two children and 40 randomly selected DS children without known hematological disorder. A rare case of a non-DS neonate with TMD and clonal trisomy 21 were also examined. Genomic DNA was extracted and the exon 2 of GATA1 was PCR amplified as described by Wechsler et al. PCR products were sequenced in both directions and analyzed in a MegaBACE 1000 automated sequencer. Presently, GATA 1 mutations were found in 7 cases of AL, in all TMD cases with DS and none MDS case of DS. Interesting, a neonate girl with no phenotypic features of DS, but TMD features whose karyotype revealed 47, XX, +21/46, XX mosaics. A G-to-T transversion was detected which is predicted to result in a premature stop codon (c.119G>T; p.Glu67X) at the time of onset of TMD. However this same mutation was not detcted at 5 years of age.To our knowledge, this is the first reported case of TMD without DS with a detected GATA1 mutation. The presence of both somatically acquired abnormalities probably confers a proliferative advantage to the cell, resulting in TMD. We postulated in this case that both genetic abnormalities were temporary because of the non self-renewing nature of the progenitor that first had a non-disjunction event and this progenitor and the proliferative clone eventually disappeared. Therefore, even the proliferative advantage that the combination of trisomy 21 and GATA1 mutation confer, maintenance of these genetic changes are necessary for full leukemic transformation and persistence.

Cytogenetic, Molecular and FISH Analysis of an Isodicentric Chromosome 21 idic(21)(q22.3) in a Mildly-Affected Patient with Down Syndrome

2007 ◽  
Vol 7 (3) ◽  
pp. 215-218 ◽  
Author(s):  
Frenny J Sheth ◽  
Uppala Radhakrishna ◽  
Michael A Morris ◽  
Jean-Louis Blouin ◽  
Jayesh J Sheth ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Chromosome 21 ◽  
Fish Analysis ◽  
Affected Patient ◽  
Isodicentric Chromosome

Molecular Cytogenetic Classification of Down Syndrome and Screening of Somatic Aneuploidy in Mothers

2021 ◽  
pp. 1-9
Author(s):  
Sushil Kumar Jaiswal ◽  
Ashok Kumar ◽  
Amit Kumar Rai
Keyword(s):  
Down Syndrome ◽  
Peripheral Blood ◽  
Trisomy 21 ◽  
Health Management ◽  
Chromosome 21 ◽  
Robertsonian Translocations ◽  
Significant Difference ◽  
And Control

Down Syndrome (DS) caused by trisomy 21 results in various congenital and developmental complications in children. It is crucial to cytogenetically diagnose the DS cases early for their proper health management and to reduce the risk of further DS childbirths in mothers. In this study, we performed a cytogenetic analysis of 436 suspected DS cases using karyotyping and fluorescent in situ hybridization. We detected free trisomies (95.3%), robertsonian translocations (2.4%), isochromosomes (0.6%), and mosaics (1.2%). We observed a slightly higher incidence of DS childbirth in younger mothers compared to mothers with advanced age. We compared the somatic aneuploidy in peripheral blood of mothers having DS children (MDS) and control mothers (CM) to identify biomarkers for predicting the risk for DS childbirths. No significant difference was observed. After induced demethylation in peripheral blood cells, we did not observe a significant difference in the frequency of aneuploidy between MDS and CM. In conclusion, free trisomy 21 is the most common type of chromosomal abnormality in DS. A small number of DS cases have translocations and mosaicism of chromosome 21. Additionally, somatic aneuploidy in the peripheral blood from the mother is not an effective marker to predict DS childbirths.

scholarly journals Gambaran Erupsi Gigi Permanen pada Anak Sindrom Down Usia 10-16 Tahun di Sekolah Luar Biasa Kabupaten Jember

2018 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Loly Anastasya Sinaga ◽  
Dwi Kartika Apriyono ◽  
Masniari Novita
Keyword(s):  
Down Syndrome ◽  
Special Needs ◽  
Physical Characteristic ◽  
Trisomy 21 ◽  
Genetic Disorder ◽  
Extra Chromosome ◽  
Descriptive Study ◽  
Chromosome 21 ◽  
Permanent Teeth ◽  
Intellectual Abilities

Background: Down Syndrome is a genetic disorder that occurs because of chromosome 21 has three chromosome (trisomy 21). The extra chromosome changes the genetic balance, physical characteristic, intellectual abilities, and physiological body function. Tooth eruption in Down Syndrome children typically delayed in both the timing and sequence of eruption up to two or three years. Objective: To observe the permanent teeth eruption in Down syndrome children at age 10-16 years old, boys and girls in Special Needs School in Jember. Materials and Methods: This research was a descriptive study with 7 subjects. Each subject was examined then calculated teeth that had emerged or functionally eruption with articualting paper. Result and Conclusion:  Both permanent teeth that is still partially erupted tooth (emerged/ EM) and had erupted perfectly (functionally eruption/ FE) delayed in eruption in Down Syndrome boys and girls at age 10-16 years old.

scholarly journals Partial trisomy 21 map: Ten cases further supporting the highly restricted Down syndrome critical region (HR‐DSCR) on human chromosome 21

2019 ◽  
Vol 7 (8) ◽  
Author(s):  
Maria Chiara Pelleri ◽  
Elena Cicchini ◽  
Michael B. Petersen ◽  
Lisbeth Tranebjærg ◽  
Teresa Mattina ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Human Chromosome ◽  
Critical Region ◽  
Trisomy 21 ◽  
Partial Trisomy ◽  
Chromosome 21 ◽  
Human Chromosome 21

GATA1 Mutations in Newborns with Down Syndrome.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 641-641
Author(s):  
Claudio Sandoval ◽  
Sharon R. Pine ◽  
Charlotte Druschel ◽  
Somasundaram Jayabose ◽  
Qianxu Guo ◽  
...  
Keyword(s):  
New York ◽  
Down Syndrome ◽  
Single Strand Conformation Polymorphism ◽  
Protein Product ◽  
Polymorphism Analysis ◽  
Exon 2 ◽  
Blood Spots ◽  
Increased Risk ◽  
Significant Difference ◽  
Gata1 Mutation

Abstract Somatic mutations of the GATA1 gene have been detected in almost all cases of Down syndrome (DS)-associated acute megakaryoblastic leukemia (AMKL) and transient leukemia (TL). There is emerging evidence that the protein product of GATA1 mutations, GATA1s, directly contributes to leukemogenesis. Although an in utero origin of GATA1 mutations is established, a comprehensive study using a large number of cases is required to determine the overall incidence and clinical relevance of GATA1 mutations in DS newborns. We screened 575 DS infants born between January 1997 and December 1999 for GATA1 exon 2 mutations by single-strand conformation polymorphism analysis of PCR products. We used Gunthrie cards obtained from the New York Congenital Malformation Registry. Registry data was blinded until after the GATA1 mutation analyses were completed. Twenty-eight (4.9%) infants were identified as having a GATA1 mutation. There was no significant difference in the frequency of GATA1 mutations based on gender or maternal average age (p = 0.93 and 0.31, respectively). There was no significant difference in the GATA1 mutation frequency between those classified as black, white, or Asian, but Hispanics had a borderline non-significant increase in frequency of GATA1 mutations compared to non-Hispanics (8.5% compared to 4.0%, p=0.06). Based on data from the New York Cancer Registry reviewed in 2005, two of the patients with a GATA1 mutation subsequently developed leukemia; one patient developed AMKL and the other had a leukemia of unspecified phenotype. Out of the 547 GATA1-negative patients, there was only one case of leukemia, but it was AML excluding AMKL. These results confirm a pre-natal origin of GATA1 mutations in DS patients. The frequency in this study was lower than the 10 percent previously reported (2 of 21 DS blood spots). Obtaining Gunthrie card blood spots for GATA1 mutation analysis serves as a relatively non-invasive screening approach. The presence of a GATA1 mutation at the time of birth might serve as a biomarker for an increased risk of developing DS-related AMKL.

A High Resolution Analysis of Chromosome 21 Amplification In Myeloid Malignancies Reveals An Association with a Specific Cytogenetic Subgroup and Enhanced ERG Gene Expression.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1687-1687
Author(s):  
Hideki Makishima ◽  
Hideki Muramatsu ◽  
Asahito Hama ◽  
Ramon V. Tiu ◽  
Yuka Sugimoto ◽  
...  
Keyword(s):  
Gene Expression ◽  
Down Syndrome ◽  
High Resolution ◽  
Copy Number ◽  
Trisomy 21 ◽  
Chromosome 21 ◽  
Mrna Levels ◽  
Myeloid Malignancies ◽  
Runx1 Gene ◽  
Cd34 Cells

Abstract Abstract 1687 Genetic alterations including chromosomal translocation, somatic mutation, and gene amplification are thought to play a key role in oncogenesis. Gains of whole or segmental chromosome 21 (Ch21) are observed in many types of myeloid malignancies and are often associated with acute megakaryoblastic leukemia (AMKL). In Down syndrome, transient abnormal myelopoiesis and acute lymphoblastic leukemia can be observed, but the prevalence of AMKL is striking. In rare Down syndrome patients, a subcytogenetic Ch21 minimal amplified region is observed and always found to include ERG as well as the RUNX1 gene locus. Recently, gain of ERG gene copy number has been demonstrated to induce leukemia in mouse models and mutations in RUNX1 have been reported in patients with myeloid malignancies with somatic trisomy 21. The pathogenic gene(s) driving malignant disease in congenital and/or somatic gain of Ch21 are poorly understood. We applied high resolution single nucleotide polymorphism array (SNP-A) to study whether small copy number gains are present on Ch21, which cannot be seen by metaphase cytogenetics. We also tested for potential synergistic karyotypic abnormalities in the patients with gain of Ch21 gene segments. We screened a large cohort of 522 patients with myeloid malignancies by SNP-A platform, and detected 36 events that included whole or partial amplification of Ch21 in 32 cases (6%). The affected length was between 215,063 and 46,944,323 bp and the average was 30,732,002. These include 13 congenital lesions (AMKL evolving in Down syndrome), and 23 somatic alterations. Among the AMKL cohort of 34 cases, gains of Ch21 were observed in 15/25 (60%) juvenile and 2/9 (22%) adult cases. A minimal consensus amplification region was defined from nt38637816 to nt38852879 on Ch21 and this region included ERG. Amplification of ERG was identified in 30/36 of the Ch21 gain lesions studied. Although we sequenced all exons of the ERG gene in all cases with Ch21 gain, no mutation was detected. Based on the possibility that gene amplification leads to increased gene expression, ERG mRNA levels were investigated. CD34+ cells showed the highest ERG expression among hematopoietic cell types. When CD34+ cells from acute myeloid leukemia (AML) patients with somatic trisomy 21, with normal copy of Ch21 and healthy donors were investigated by real time PCR, relative expression of ERG was the highest in trisomy 21 patients among three groups. Based on our previous work and that of others, we tested the mutational status of RUNX1 in the 23 cases with Ch21 amplification that included RUNX1. Mutations were found in 2/23 (9%) accompanied by trisomy 21. No mutation was found in patients with Down syndrome. In one mutant case, a homozygous missense mutation, (L56S) was identified and associated with uniparental trisomy that included RUNX1. The second mutant case (W106L) was in a patient with a 45,XY,-7,i(21)(q10) karyoptype. The mutation was duplicated but was not associated with loss of heterozygosity (LOH). When RUNX1 gene expression in the cases with and without trisomy 21 using CD34 positive bone marrow cells was investigated, no significant difference in relative RUNX1 mRNA levels between trisomy 21 and cases with diploid Ch21 was found. Finally, we evaluated whether additional chromosomal lesions were associated with a gain of Ch21 gene segments. Recurrent losses were detected on chromosome 1, 2, 3, 5, 7, 9, and 17. Deletions of 5q were frequent in the cases with somatic gain of Ch21 (47%; 8/17), while no del5q was detected in the cases with Down syndrome. Conversely, LOH17p (3 uniparental disomies (UPDs) and 2 deletions) was found in both somatic and congenital cases (5/32), with one case of deletion17p associated with a hemizygous p53 mutation. In addition, UPD11q was accompanied by a CBL homozygous mutation in a RAEB case with somatic trisomy 21. Del7q was also observed in both groups (4 in somatic and 3 in congenital cases), including a 7q36.1 microdeletion associated with EZH2 in AMKL with Down syndrome. In sum, our study demonstrates that high resolution SNP-A analysis focused on Ch21 gene segments revealed frequent cryptic somatic gain lesions and a uniparental trisomy. ERG was the sole gene located in the minimally shared gain lesions and is overexpressed in a wild type form in AML cases with somatic trisomy 21. RUNX1 mutations were found in 3 or 2 identical alleles of somatic trisomy 21 cases but are absent in most cases of trisomy 21. Disclosures: No relevant conflicts of interest to declare.

Imbalances of Chromosome 21 in MDS/AML Include Cryptic Deletions but NOT RUNX1 Amplifications.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2561-2561
Author(s):  
Katya Gancheva ◽  
Diana Brazma ◽  
Nahid Zarein ◽  
Julie Howard-Reeves ◽  
Phaidra Partheniou ◽  
...  
Keyword(s):  
Down Syndrome ◽  
De Novo ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Extra Chromosome ◽  
Chromosome 21 ◽  
Oligonucleotide Array ◽  
Fish Analysis ◽  
Extra Copy ◽  
Commercial Fish

Abstract Abstract 2561 We present the results of a study demonstrating that the genome profile of RUNX1 in MDS/AML is characterised by hitherto unreported partial deletions and absence of amplifications. This is in stark contrast to reports of chromosome 21 amplifications in ALL. We speculate that the absence of RUNX1 deletions results from them being well below a size detectable by commercial FISH probes. Extra chromosome 21 is the second most common acquired trisomy after (+) 8 in adult myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). It is rarely observed as sole abnormality but seen as part of complex karyotype in some 3–7% of the AML (Atlas of Genetics and Cytogenetics in Oncology and Haematology, http://atlasgeneticsoncology.org). Although the gene(s) in trisomy 21 associated with leukemia are unknown, the 21q22 region appears to be critical since it houses the RUNX1 gene. Multiple amplified copies of the RUNX1 carried by marker chromosomes, such as iAML21, are described in both acute lymphoblastic leukemia (ALL) and AML. A common 5.1 Mb amplification containing the RUNX1, miR-802 and genes mapping to the Down syndrome critical region identified in 91 children with iAML21, was shown to be the likely initiating event in this rare form of childhood B-cell ALL (Rand et al., Blood, 2011). In contrast, recent studies of AML in a Down syndrome and a constitutionally normal individual showed lack of RUNX1, ETS2 and ERG involvement (Canzonetta et al., BJH, 2012). Here we present 16 MDS/AML cases with imbalances of chromosome 21 identified by genomic array screening from a cohort of 83 cases. Whole genome screening (aCGH) was performed on presentation samples of MDS /AML and de novo AML cases using an oligonucleotide array platform (Agilent) at 60K, 244K, 400K and 1M density. G banding and FISH analysis were also successfully performed. Gain of an extra copy (trisomy) of chromosome 21 (+21) was found in 9 patients, all but one with complex karyotypes. In 2 AMLs high level amplifications were detected at 21q22, which involved the ETS2 and ERG but not the RUNX1 sequences. While several commercially available RUNX1 FISH probes showed gene multiple signals, custom FISH probes covering the relevant regions confirmed that the amplifications excluded the RUNX1 but affected both EST2 and ERG thus rendering the commercial probes unfit to assess CNA in this genome area. In another two cases with trisomy 12, cryptic loss of 43Kb and 98Kb resp. within the RUNX1 sequences was detected and confirmed by FISH. Furthermore, similar deletions within the 21q22.12 were also found in another 7 cases all of which had diploid set of chromosome 21 but had multiple changes at G banding level and high TGA score. These RUNX1 deletions were variable in size, ranging from 98Kb to 2.7Mb. Although our observations excluded clinical correlations it is note worthy that most of the patients with RUNX1 loss have not achieved complete cytogenetic remission. These findings suggest role for the RUNX1 loss as indicator of progressive disease and provide a novel insight into pathogenesis of MDS/AML. Disclosures: No relevant conflicts of interest to declare.

High Frequency of GATA1 Mutations in Childhood Non-Down Syndrome Acute Megakaryoblastic Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 888-888 ◽  
Author(s):  
Katarina Reinhardt ◽  
C. Michel Zwaan ◽  
Michael Dworzak ◽  
Jasmijn D.E. de Rooij ◽  
Gertjan Kaspers ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Down Syndrome ◽  
Trisomy 21 ◽  
Mutation Screening ◽  
Study Group ◽  
Acute Megakaryoblastic Leukemia ◽  
Monosomy 7 ◽  
Megakaryoblastic Leukemia ◽  
Exon 1 ◽  
Gata1 Mutation

Abstract Abstract 888 Introduction: Pediatric acute megakaryoblastic leukemia (AMKL) occurred in 6.6% (84/1271) of the children enrolled to the AML-BFM98 and 2004 studies. Despite a similar phenotype in morphology and immunophenotype, AMKL shows a heterogenous cytogenetic distribution (normal karyotype 23%, complex karyotype 21%, t(1;22) 9%; MLL-rearrangement 8%; monosomy 7 5%, trisomy 8 5%; other aberrations 29%). Mutations of the hematopoietic transcription factor GATA1 have been identified in almost all children suffering myeloid leukemia of Down syndrome (ML-DS). In addition, GATA1 mutations (GATA1mut) could be identified in children with trisomy 21 mosaic. Here, AMKL without evidence of Down syndrome or Down syndrome mosaic were analyzed for mutations in exon 1, 2 or 3 of the transcription factor GATA1. Patients: Seventy-one children from the AML-BFM Study group (n=51; 2000–2011), the Netherlands (n=10), France (n=3) and Scandinavia (n=7) were included. Within the AML-BFM Group the 51 analyzed patients showed similar characteristics compared to the total cohort of 84 children with AMKL of the AML-BFM 98 and 2004 studies. AMKL was confirmed according to the WHO classification by genetics (t(1;22)); morphology and immunophenotyping. Table 1a) summarizes the patientxs characteristics and b) the cytogenetic results. Methods: For GATA1 mutation screening genomic DNA was amplified by PCR reaction for exon 1, 2, and 3. PCR amplicons were analyzed by direct sequencing or following denaturing high-performance liquid chromatography (WAVE). Results: Seven different GATA1 mutations were detected in 8 children (11.1%; table 2). In all GATA1mut leukemia, a trisomy 21 within the leukemic blasts could be detected. Seven out of these 8 children and all other 64 AMKL patients have been treated with intensive chemotherapy regimens according the study group protocols. The results are given in table 2. All achieved continuous complete remission (CCR; 0.4 to 4.2 years). In one newborn with typical morphology and immunophenotype a GATA1mut associated transient leukemia was supposed. The child achieved CCR (follow-up 6 years). In total, allogeneic stem cell transplantation in 1st CR was performed in 6 children with AMKL (GATA1mut leukemia n=1). Conclusions: GATA1 mutations occurred in 11% of children with AMKL without any symptoms or evidence of trisomy 21 or trisomy 21 mosaic. GATA1 mutations are associated with a trisomy 21 within the leukemic blasts. Although non-response occurred, prognosis was significant better compared to other AMKL. Therefore, analysis of GATA1 mutation in infant AMKL is strongly recommended. Whether treatment reduction similar to ML-DS Down syndrome is feasible needs to be confirmed. Disclosures: No relevant conflicts of interest to declare.

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