Quantitative Analysis of Wilms’ Tumor Gene 1(WT1) Expression in Acute Lymphoblastic Leukemia (ALL) of Adults Reveals Lower WT1 Levels Than in Acute Myeloid Leukemias (AML) and Varying Expression Levels between Individual Patients among Different ALL Subgroups.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 4545-4545
Author(s):  
Jan M. Siehl ◽  
Eckhard Thiel ◽  
Dieter Hoelzer ◽  
Stefan Schwartz ◽  
Ulrich Keilholz
Keyword(s):  
Quantitative Analysis ◽  
Wilms Tumor ◽  
Lymphoblastic Leukemia ◽  
Expression Patterns ◽  
Pcr Analysis ◽  
Published Data ◽  
Rt Pcr ◽  
Acute Leukemias ◽  
Expression Levels ◽  
Pcr Technology

Abstract Background: Overexpression of the embryonic transcription factor WT1 is common in human acute leukemias. Therefore WT1 became an interesting target mainly for immunotherapeutic approaches in AML. In previously published data from qualitative PCR analysis the frequency of WT1 overexpression in ALL is lower than in AML. But so far only limited data from quantitative analysis of WT1 expression in ALL are available. Methods: In the present study we analysed bone marrow or blood samples of 238 adult ALL patients at diagnosis for the expression levels of WT1 by real-time RT - PCR (LightCycler). All patients were treated in the German Multicenter Study for the Treatment of ALL (GMALL 07/2003). Only samples containing at least 60 % blasts were used for analysis. Expression levels were compared to previously published data of WT1 expression levels in AML samples. Results: WT1 expression was found in 219 out of 238 ALL samples (92 %). Compared to AML WT1 expression levels in ALL were significantly lower. There were no differences between the various ALL immuno phenotypes of the B or T lineage, but lymphoblasts with a coexpression of myeloid markers had significantly higher WT1 expression levels than those without a coexpression of myeloid markers. Surprisingly, patients who were bcr-abl negative had significantly higher WT1 expression levels than bcr-abl positive patients. Conclusions: Using quantitative RT-PCR technology WT1 expression can be found in most ALL cases. There are usually less intense expression patterns compared to AML and expression varies among different ALL subgroups. Thus WT1 has promise to be an interesting target also in ALL therapy but in a more individually determined fashion. The relation of WT1 expression level and treatment outcome is currently being analysed.

Detection of the NUP214-ABL Rearrangement in T-ALL by High-Density Oligonucleotide Arrays: Evidence of the Value of This Approach in the Identification of Gene Amplifications.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1211-1211
Author(s):  
Sabina Chiaretti ◽  
Simona Tavolaro ◽  
Emanuela Ghia ◽  
Cristina Ariola ◽  
Caterina Matteucci ◽  
...  
Keyword(s):  
Microarray Analysis ◽  
Lymphoblastic Leukemia ◽  
Marker Chromosome ◽  
Rare Event ◽  
Leukemic Cells ◽  
Pcr Analysis ◽  
Fish Analysis ◽  
Rt Pcr ◽  
Expression Levels ◽  
B Lineage

Abstract The translocation t(9;22), hallmark of CML, is also detected in B-lineage acute lymphoblastic leukemia (ALL). This aberration leads to the BCR/ABL rearrangement that induces a constitutive activation of the tyrosine kinase ABL1. Although BCR/ABL rearrangements were previously considered a rare event in T-ALL, recent data showed the involvement of ABL1 also in this malignancy. Specifically, a new fusion gene involving ABL1 and NUP214, both located at the 9q34 region, has been reported. This abnormality was detected by FISH analysis and reconfirmed by array CGH and PCR analysis. We previously evaluated by microarrays a set of 128 adults with ALL: leukemic cells from 33 patients were of T-cell origin. In the present study, we analyzed the expression levels of ABL1, with the aim of identifying T-ALL cases who may have an involvement of ABL1. Overall, mean expression levels of ABL1 were: pre-B BCR/ABL+ ALL: 1202.71 ± 67.15; pre-B BCR/ABL- ALL: 629.06 ± 23.91; T-ALL: 758.56 ± 42.26, indicating that ABL1 is more highly expressed in T-lineage ALL than in BCR/ABL-B-lineage ALL. Detailed analysis of the T-ALL subset identified 3 cases who had very high levels of ABL1, comparable to those expressed in the BCR/ABL+ cases, and 1 further case with ABL1 expression levels higher than the mean values of BCR/ABL+ cases. Notably, 3/4 patients were refractory to induction chemotherapy. To understand the mechanisms underlying overexpression of ABL1, reverse transcriptase PCR (RT-PCR) was performed and showed the presence of the NUP214-ABL1 in the case having the highest levels of ABL1, whereas the remaining 3 cases were negative. FISH analysis confirmed the presence of NUP214-ABL1 in this case. Quantitative PCR (Q-PCR) of the ABL1 gene was also performed on the same set of T-ALL cases and showed a high degree of correlation between microarray analysis and Q-PCR. HOX11 expression was increased in 2/3 cases, but was not exclusive of these samples; HOX11L2 expression was not evaluated because this transcript was not represented in the platform used. However, FISH analysis excluded the presence of the t(5;14) in all 3 cases. Conventional cytogenetics revealed a normal karyotype in 1 patient, a 4p deletion and an additional marker chromosome in 1, a del(6q) in the case with the highest ABL expression, and was not evaluable in 1. Similarly, CGH analysis showed unbalances in all cases. None of these cases carried a deletion of CDKN2A. Following these findings, we evaluated by both Q-PCR and RT-PCR 15 newly diagnosed T-ALL patients: none of them showed high levels of ABL1. In summary, these results show the value of microarray analysis for the identification of cases carrying specific chromosomal amplifications, i.e. NUP214-ABL1. To our knowledge, this is the first report that identifies this DNA amplification by investigating RNA expression levels of the corresponding transcript. Moreover, our results indicate that this aberration is less frequent than previously reported, being detected in our overall series in 2% of cases. Further investigations are ongoing on the remaining 3 samples to explain the mechanisms underlying ABL overexpression.

Expression of Wilms’ Tumor Gene 1 and Its Clinical Significance in Children with Acute Lymphocytic Leukemia

2020 ◽  
Author(s):  
Mengmeng Yin ◽  
Aiguo Liu ◽  
Ai Zhang ◽  
Yaqin Wang ◽  
Qun Hu
Keyword(s):  
Bone Marrow Cells ◽  
Wilms Tumor ◽  
Lymphoblastic Leukemia ◽  
Quantitative Polymerase Chain Reaction ◽  
Lymphocytic Leukemia ◽  
Fusion Genes ◽  
Childhood All ◽  
Expression Levels ◽  
Wilms Tumor Gene ◽  
Tumor Gene

Abstract Background: Wilms’ Tumor Gene 1 (WT1) is a potential valuable parameter in prognosis of childhood acute lymphoblastic leukemia (ALL). However, studies on prevalence of WT1 and its correlation to clinical features and prognosis in pediatric patients were not well done. In this study we attempted to identify the correlation between WT1 and childhood ALL.Methods: The expression levels of WT1 in bone marrow cells of 188 children diagnosed with ALL from 2015 to 2018 were detected using real-time quantitative polymerase chain reaction (RQ-PCR). The relationship between expression levels of WT1 and patients’ characteristics, remission status (complete remission/relapse), fusion genes and prognosis of childhood ALL were analyzed and revealed. Results: 1. 147 (78.2%) cases had positive WT1 expression, and the average level was 1.76 (0.3, 6.03) %. 2. The CR and relapse rates of ALL children with positive WT1 were not significantly different from those of WT1 negative group, respectively (87.76% vs 82.93%, P=0.42 and 14.29% vs 17.1%, P=0.658). 3. The WT1 expression level in patients at CR was significantly lower than when at diagnosis (P<0.001) and the expression of WT1 increased obviously after induction therapy in 21 patients who relapsed (P=0.003) .4. The WT1 expression was related to lymphadenectasis (P=0.004) and immunophenotyping (P=0.009), but not to fusion genes (P=0.912). Conclusion: The WT1 in ALL children can be employed as an independent tool to evaluate the prognosis and curative effect of the disease.

scholarly journals Neural Differentiation of Human Adipose Tissue-Derived Stem Cells Involves Activation of the Wnt5a/JNK Signalling

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Sujeong Jang ◽  
Jong-Seong Park ◽  
Han-Seong Jeong
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Neural Differentiation ◽  
Neural Induction ◽  
Stem Cell Differentiation ◽  
Human Adipose Tissue ◽  
Pcr Analysis ◽  
Rt Pcr ◽  
Jnk Pathway ◽  
Expression Levels

Stem cells are a powerful resource for cell-based transplantation therapies, but understanding of stem cell differentiation at the molecular level is not clear yet. We hypothesized that the Wnt pathway controls stem cell maintenance and neural differentiation. We have characterized the transcriptional expression of Wnt during the neural differentiation of hADSCs. After neural induction, the expressions of Wnt2, Wnt4, and Wnt11 were decreased, but the expression of Wnt5a was increased compared with primary hADSCs in RT-PCR analysis. In addition, the expression levels of most Fzds and LRP5/6 ligand were decreased, but not Fzd3 and Fzd5. Furthermore, Dvl1 and RYK expression levels were downregulated in NI-hADSCs. There were no changes in the expression of ß-catenin and GSK3ß. Interestingly, Wnt5a expression was highly increased in NI-hADSCs by real time RT-PCR analysis and western blot. Wnt5a level was upregulated after neural differentiation and Wnt3, Dvl2, and Naked1 levels were downregulated. Finally, we found that the JNK expression was increased after neural induction and ERK level was decreased. Thus, this study shows for the first time how a single Wnt5a ligand can activate the neural differentiation pathway through the activation of Wnt5a/JNK pathway by binding Fzd3 and Fzd5 and directing Axin/GSK-3ß in hADSCs.

scholarly journals Transcriptional Profiling of Methyltransferase Genes during Growth of Methanosarcina mazei on Trimethylamine

2009 ◽  
Vol 191 (16) ◽  
pp. 5108-5115 ◽  
Author(s):  
Christian Krätzer ◽  
Paul Carini ◽  
Raymond Hovey ◽  
Uwe Deppenmeier
Keyword(s):  
Transcriptional Profiling ◽  
Expression Patterns ◽  
Pcr Analysis ◽  
Exponential Growth Phase ◽  
Methane Formation ◽  
Rt Pcr ◽  
Transcript Levels ◽  
Methanosarcina Mazei ◽  
Depth Analysis ◽  
Genes Encoding

ABSTRACT The genomic expression patterns of Methanosarcina mazei growing with trimethylamine were measured in comparison to those of cells grown with methanol. We identified a total of 72 genes with either an increased level (49 genes) or a decreased level (23 genes) of mRNA during growth on trimethylamine with methanol-grown cells as the control. Major differences in transcript levels were observed for the mta, mtb, mtt, and mtm genes, which encode enzymes involved in methane formation from methanol and trimethylamine, respectively. Other differences in mRNA abundance were found for genes encoding enzymes involved in isopentenyl pyrophosphate synthesis and in the formation of aromatic amino acids, as well as a number of proteins with unknown functions. The results were verified by in-depth analysis of methyltransferase genes using specific primers for real-time quantitative reverse transcription-PCR (RT-PCR). The monitored transcript levels of genes encoding corrinoid proteins involved in methyl group transfer from methylated C1 compounds (mtaC, mtbC, mttC, and mtmC) indicated increased amounts of mRNA from the mtaBC1, mtaBC2, and mtaBC3 operons in methanol-grown cells, whereas mRNA of the mtb1-mtt1 operon was found in high concentrations during trimethylamine consumption. The genes of the mtb1-mtt1 operon encode methyltransferases that are responsible for sequential demethylation of trimethylamine. The analysis of product formation of trimethylamine-grown cells at different optical densities revealed that large amounts of dimethylamine and monomethylamine were excreted into the medium. The intermediate compounds were consumed only in the very late exponential growth phase. RT-PCR analysis of key genes involved in methanogenesis led to the conclusion that M. mazei is able to adapt to changing trimethylamine concentrations and the consumption of intermediate compounds. Hence, we assume that the organism possesses a regulatory network for optimal substrate utilization.

Differential Expression of ERG Isoforms in Acute Myeloid and T-Lymphoblastic Leukemia Is Regulated by DNA-Methylation.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2126-2126
Author(s):  
Claudia D. Baldus ◽  
Cornelia Schlee ◽  
Julia Thibaut ◽  
Sandra Heesch ◽  
Arend Bohne ◽  
...  
Keyword(s):  
Differential Expression ◽  
Cpg Island ◽  
Lymphoblastic Leukemia ◽  
Prognostic Significance ◽  
Rt Pcr ◽  
Acute Leukemias ◽  
Aberrant Expression ◽  
Cd34 Cells ◽  
Exon 4 ◽  
Acute Myeloid

Abstract The oncogenic ETS transcription factor ERG is involved in various cellular pathways including developmental regulation, proliferation, and differentiation. In hematopoiesis ERG plays a specific role during normal T-cell differentiation showing high expression levels in stem cells and down regulation in the progenitor compartment. In this regard, it is intriguing that aberrant expression of ERG was found in a subset of patients with acute T-lymphoblastic leukemia (T-ALL) and was associated with an inferior outcome. Furthermore, high level ERG expression was of adverse prognostic significance in patients with newly diagnosed acute myeloid leukemia (AML), thus highlighting ERG’s potential role in myeloid as well as T-lineage leukemogenesis. ERG3 (NM_182918) and ERG2 (NM_004449) represent the main isoforms and show abundant expression in myeloid and lymphoid hematopoietic progenitor cells. The expression pattern of specific ERG isoforms in acute leukemias has yet to be investigated. To further elucidate the nature of aberrant ERG expression we have determined the existence and transcriptional regulation of ERG isoforms in pretreatment bone marrow samples of adult T-ALL (n=21) and AML (n=20) patients as well as in normal CD34+ hematopoietic cells of healthy volunteers (n=5). 5′RACE revealed the presence of a new ERG isoform (ERG3Δex12) characterized by expression of exon 5 and absence of exon 12. Expression of ERG3Δex12 was verified by RT-PCR in AML, T-ALL, and CD34+ cells. In addition, real-time RT-PCR showed concomitant expression of the two main isoforms ERG2 and ERG3 in AML and normal CD34+ cells. In contrast, T-ALL patients lacked expression of ERG isoforms harboring exon 4 (ERG2). Promoter analyses of ERG2 and ERG3 revealed the presence of two CpG islands in the ERG2 promoter region, whereas no CpG island was predicted in the ERG3 promoter. Bisulfit conversion of genomic DNA and sequencing of cloned PCR products revealed a significantly higher degree of methylation of CpG island 2 in T-ALL samples (median: 86.4%, range: 16.0 – 98.8%) as compared to AML (median: 38.1%, range: 10.9 – 60.7%; P-value=0.0002 - two sided T-test). As for CpG island 1, CD34+ cells had the lowest rate of methylation in CpG island 2 (median: 7.7%, range: 2.4 – 20.7%). Thus, the differential expression of ERG isoforms is mediated by epigenetic silencing of exon 4 containing transcripts in T-ALL. In conclusion, the identification of the new ERG isoform (ERG3Δex12) suggests the association with different partners as the central exons, including exon 12, guide the interaction with different proteins. Furthermore, the distinct expression of specific ERG transcripts controlled by methylation adds to the complexity of ERG directed downstream pathways in different leukemic subtypes.

Wilms Tumor 1 Gene Mutations in Adult Acute T-Lymphoblastic Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2516-2516
Author(s):  
Sandra Heesch ◽  
Nicola Goekbuget ◽  
Jutta Ortiz Tanchez ◽  
Cornelia Schlee ◽  
Stefan Schwartz ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Wilms Tumor ◽  
Lymphoblastic Leukemia ◽  
Single Amino Acid ◽  
Newly Diagnosed ◽  
Expression Levels ◽  
Wilms Tumor 1 ◽  
Standard Risk ◽  
Wt1 Protein ◽  
Mrna Expression Levels

Abstract The wilms tumor 1 gene (WT1) encodes a transcriptional regulator involved in normal hematopoietic development. The role of WT1 in acute leukemia has been underscored by the finding of WT1 overexpression in subsets of patients (pts) associated with an increased relapse risk. In addition mutations of WT1 have been found in about 10–15% of acute myeloid leukemia (AML) pts and have recently shown to predict inferior survival. Thus far, larger studies have not yet determined the frequency and impact of WT1 mutations in acute T-lymphoblastic leukemia (T-ALL). Herein, we have analyzed WT1 mutations and WT1 mRNA expression levels in a large cohort of T-ALL including 239 newly diagnosed adult pts treated on the GMALL protocols 0699 and 0703. Diagnostic bone marrow specimens were studied for WT1 mutations by DNA sequencing. In addition, samples were immunophenotyped, and mRNA expression of the molecular markers HOX11, HOX11L2, ERG, BAALC, as well as WT1 were determined by real-time RT-PCR. Twenty (8%) of the 239 analyzed T-ALL pts had WT1 mutations (WT1mut) [20 pts had mutations in exon 7 (WT1mut7), with 2 pts having coexisting mutations in exon 9 (WT1mut9)]. WT1mut7 were frameshift or nonsense mutations predicted to result in a truncated WT1 protein, whereas WT1mut9 were missense mutations leading to single amino-acid substitutions. WT1mut and WT1 wildtype (WTwt) pts did not significantly differ with respect to clinical parameters at diagnosis (e. g. age, leukocyte count, and sex). WT1mut cases were characterized by immature features such as an early immunophenotype (45% of WT1mut showed an early T-ALL immunophenotype as compared to only 25% of WT1wt), and WT1mut also showed higher levels of CD34 expression as determined by flow cytometry (WT1mut median: 46% vs. WT1wt median: 2 %; P=0.03). Moreover, WT1mut had significantly higher WT1 mRNA expression levels [WT1mut median: 0.05 (range: 0–0.395) vs. WT1wt median: 0 (range: 0–0.15); P&lt;0.001]. Significant differences were not observed in the complete remission rate nor overall survival or relapse free-survival (RFS) between WT1mut and WT1wt pts. However, in the standard risk group of thymic T-ALL 80% (4/5) of WT1mut relapsed as compared to 28% (25/89) of WT1wt thymic pts [P=0.01; RFS at 18 months: 20% (SE: ±18) for thymic WT1mut vs. 82% (SE: ±4) for thymic WT1wt pts; P=0.008]. In conclusion, in adult T-ALL WT1 mutations are present in 8% of newly diagnosed pts and are located in the same region as reported in AML expected to impair the DNA binding ability of the WT1 protein. Similar to findings in AML, WT1mut cases are characterized by immature features pinpointing to a genetic hit in hematopoietic progenitors likely harboring bilineage potential. The prognostic implications of WT1 mutations in standard risk thymic T-ALL will have to be further validated in independent studies and may in future direct molecularly-based treatment stratification.

HLA class II haplotype and quantitation of WT1 RNA in Japanese patients with paroxysmal nocturnal hemoglobinuria

Blood ◽  
2002 ◽  
Vol 100 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Tsutomu Shichishima ◽  
Masatoshi Okamoto ◽  
Kazuhiko Ikeda ◽  
Toshihiko Kaneshige ◽  
Haruo Sugiyama ◽  
...  
Keyword(s):  
Paroxysmal Nocturnal Hemoglobinuria ◽  
Wilms Tumor ◽  
Japanese Patients ◽  
Pcr Analysis ◽  
Healthy Individuals ◽  
Rt Pcr ◽  
Apoptosis Resistance ◽  
Mean Values ◽  
Immune Mechanisms ◽  
Pnh Clone

Abstract It is unclear how a paroxysmal nocturnal hemoglobinuria (PNH) clone expands in bone marrow, although immune mechanisms involving cytotoxic T lymphocytes, autosomal proliferation, and apoptosis resistance have been hypothesized. To clarify aspects of immune mechanisms and proliferation of PNH cells, we investigated HLA-DRB1, -DQA1, and -DQB1 alleles by polymerase chain reaction (PCR)–based genotyping and expression of the Wilms' tumor gene, WT1, by real-time reverse transcriptase–PCR (RT-PCR) in 21 PNH and 21 aplastic anemia (AA) patients. HLA genotyping indicated that the frequency of DRB1*1501, DQA1*0102, and DQB1*0602 alleles in PNH patients and of DQB1*0602 allele in AA patients was significantly higher than in 916 Japanese controls, and that the HLA-DRB1*1501-DQA1*0102-DQB1*0602 haplotype, found in 13 of 21 PNH patients, 5 of 7 AA-PNH syndrome patients, and 7 of 21 AA patients showed significant differences compared with healthy individuals. RT-PCR analysis showed that the mean values of WT1 RNA were 3413, 712, and 334 copies/μg RNA in PNH, AA, and healthy individuals, respectively. The values for PNH patients were significantly higher than for AA patients and healthy volunteers and were correlated with the proportion of CD16b−granulocytes. The high frequency of HLA-DRB1*1501-DQA1*0102-DQB1*0602 haplotype in PNH, including AA-PNH syndrome, and AA patients suggests that linkage exists between the disorders and that immune mechanisms in an HLA-restricted manner play an important role in the pathogenesis of these disorders. In addition, high expression of WT1 RNA in PNH patients is related to a PNH clone, but it remains unclear whether this causes expansion of a PNH clone.

scholarly journals Isolation, Characterization, and Expression Analysis of the MaMDH Gene in Banana

HortScience ◽  
2013 ◽  
Vol 48 (5) ◽  
pp. 614-619
Author(s):  
Cai-Hong Jia ◽  
Ju-Hua Liu ◽  
Zhi-Qiang Jin ◽  
Qiu-Ju Deng ◽  
Jian-Bin Zhang ◽  
...  
Keyword(s):  
Real Time ◽  
Quantitative Polymerase Chain Reaction ◽  
Expression Patterns ◽  
Ethylene Biosynthesis ◽  
Pcr Analysis ◽  
Malic Dehydrogenase ◽  
Reading Frame ◽  
Expression Levels ◽  
Post Harvest ◽  
Real Time Quantitative Pcr

A full-length cDNA isolated from banana (Musa acuminata L. AAA group) fruit was named MaMDH, containing an open reading frame encoding 332 amino acids that represents the gene for cytoplasmic malic dehydrogenase (MDH). Sequence analysis showed that MaMDH shares high similarity with MDHs from castor bean (XP_002533463), tobacco (CAC12826), peach (AAL11502), and chickpeas (CAC10208). Real-time quantitative polymerase chain reaction (PCR) analysis of MaMDH spatial expression showed that it was expressed in all organs examined: roots, rhizomes, leaves, flowers, and fruits. The expression was the highest in flowers followed by the fruits and roots, whereas the rhizomes and leaves displayed the lowest expression levels. Real-time quantitative PCR revealed that MaMDH exhibited differential expression patterns in post-harvest banana fruits correlating with ethylene biosynthesis. In naturally ripened banana fruits, MaMDH expression was in accordance with ethylene biosynthesis. In accordance, for banana fruits treated with the ethylene analog 1-methylclopropene (1-MCP), MaMDH expression levels were inhibited and remained constant. After treatment with ethylene, MaMDH expression in banana fruits significantly increased with ethylene biosynthesis and peaked 3 days after harvest, which was 11 days earlier than that in naturally ripened banana fruits. These results suggest that MaMDH expression is induced by ethylene to regulate post-harvest banana fruits ripening.

scholarly journals The der(11)-encoded MLL/AF-4 fusion transcript is consistently detected in t(4;11)(q21;q23)-containing acute lymphoblastic leukemia

Blood ◽  
1994 ◽  
Vol 83 (2) ◽  
pp. 330-335 ◽  
Author(s):  
JR Downing ◽  
DR Head ◽  
SC Raimondi ◽  
AJ Carroll ◽  
AM Curcio-Brint ◽  
...  
Keyword(s):  
Residual Disease ◽  
Lymphoblastic Leukemia ◽  
Leukemic Cell ◽  
Fusion Transcript ◽  
Pcr Analysis ◽  
Chromosome 11 ◽  
Rt Pcr ◽  
Pcr Products ◽  
Contrast Analysis ◽  
Leukemic Clone

The t(4;11)(q21;q23) is the most common translocation involving band 11q23 and is found predominantly in acute lymphoblastic leukemias (ALLs) of infants. Recent studies have shown that this translocation involves the MLL gene on chromosome 11 and the AF-4 gene on chromosome 4. Using oligonucleotide primers derived from these genes, we established reverse transcription-polymerase chain reaction (RT-PCR) assays for the detection of the fusion transcripts from both the der(11) and der(4) chromosomes. Using these assays we analyzed 23 pediatric cases of t(4;11) containing ALL. RT-PCR analysis for the der(11)-derived MLL/AF-4 fusion transcript resulted in its detection in every case at a sensitivity of greater than 1 leukemic cell in 10(5) cells. Sequence analysis of MLL/AF-4 PCR products demonstrated fusion mRNAs resulting from breaks in MLL introns 6, 7, or 8, with alternative splicing to one of three exons in the AF-4 gene. In contrast, analysis for the der(4)-derived transcript resulted in the detection of this chimeric mRNA in only 84% of the cases analyzed. These data suggest that the critical chimeric gene product involved in the establishment of the leukemic clone is derived from the der(11) chromosome. Moreover, these data demonstrate the utility of the RT-PCR assay for the der(11)- encoded message both for diagnosing t(4;11)-containing leukemia and for monitoring patients for minimal residual disease.

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