Amplification Of MLL Gene Research Articles

Fishing for ETV6/RUNX1 fusion and MLL gene rearrangements and their additional abnormalities in childhood acute lymphoblastic leukemia patients of Kashmir

ObjectiveEvidence suggests that ETV6/RUNX1 translocation in pediatric acute lymphocytic leukemia shows geographical variation. Therefore, the present study aimed at unveiling the incidence of ETV6/RUNX1 fusion in pediatric acute lymphocytic leukemia cases of this region using fluorescent in-situ hybridization. Besides, we aimed to determine the incidence of MLL gene rearrangement and the pattern of chromosomal abnormalities in this study group. MethodsSamples from 57 acute lymphocytic leukemia cases of pediatric age group were subjected to fluorescent in-situ hybridization and conventional cytogenetic analysis using standard methods. ResultsConventional cytogenetic analysis revealed chromosomal abnormalities in 19.3% cases. The other major chromosomal abnormalities reported were monosomies in 10.5%, hypodiploidy in 7%, marker chromosomes in 3.5% and deletions in 3.5% cases. We found a 44,XX,-7,-18, r(5), i(17q) complex karyotype in one of the cases. Fluorescent in-situ hybridization analysis revealed ETV6/RUNX1 translocation to be present in 28.07% cases and MLL gene rearrangement in 3.5% cases. 12.5% of ETV6/RUNX1 fusion positive cases were found to have a loss of ETV6 allele. Besides, 8.8% cases were found to exhibit a signal pattern suggestive of RUNX1 amplification. ETV6 gene deletion and MLL gene amplification was detected in 3.5% cases each, of our study. ConclusionsFrequency of ETV6/RUNX1 fusion oncogene was found to be higher in pediatric ALL cases of Kashmir region as compared to that reported from other parts of India. Besides, a case was found to have a karyotype viz 44,XX,-7,-18, r(5), i(17q) that has not been reported elsewhere in the childhood ALL.

Double minute chromosomes in acute myeloid leukemia, myelodysplastic syndromes, and chronic myelomonocytic leukemia are associated with micronuclei, MYC or MLL amplification, and complex karyotype

Double minute chromosomes (dmin) are small, paired chromatin bodies that lack a centromere and represent a form of extrachromosomal gene amplification. Dmin are rare in myeloid neoplasms and are generally associated with a poor prognosis. Most studies of dmin in myeloid neoplasms are case reports or small series. In the current study, we present the clinicopathologic and cytogenetic features of 22 patients with myeloid neoplasms harboring dmin. These neoplasms included acute myeloid leukemia (AML) (n = 18), myelodysplastic syndrome (MDS) (n = 3), and chronic myelomonocytic leukemia (CMML) (n = 1). The AML cases consisted of AML with myelodysplasia-related changes (n = 13) and therapy-related AML (n = 5). Dmin were detected in initial pre-therapy samples in 14 patients with AML or CMML; they were acquired during the disease course in 8 patients who had AML or MDS. The presence of dmin was associated with micronuclei (18/18; 100%), complex karyotype (17/22; 77.3%), and amplification of MYC (12/16; 75%) or MLL (4/16; 25%). Immunohistochemical staining for MYC performed on bone marrow core biopsy or clot sections revealed increased MYC protein in all 19 cases tested. Except for one patient, most patients failed to respond to risk-adapted chemotherapies. At last follow up, all patients had died of disease after a median of 5 months following dmin detection. In conclusion, dmin in myeloid neoplasms commonly harbor MYC or MLL gene amplification and manifest as micronuclei within leukemic blasts. Dmin are often associated with myelodysplasia or therapy-related disease, and complex karyotypes.

MLL gene amplification in acute myeloid leukemia and myelodysplastic syndromes is associated with characteristic clinicopathological findings and TP53 gene mutation.

MLL gene rearrangements are well-recognized aberrations in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). In contrast, MLL gene amplification in AML/MDS remains poorly characterized. Here, we report a series of 21 patients with myeloid neoplasms associated with MLL gene amplification from 1 institution. This series included 13 men and 8 women, with a median age of 64 years. Eleven patients presented as AML with myelodysplasia-related changes, 6 as therapy-related AML, and 4 as therapy-related MDS. All patients had a highly complex karyotype, including frequent -5/del(5q), -18, and -17/del(17p) abnormalities; 16 patients were hypodiploid. TP53 mutations were detected in all 12 patients tested, and 3 patients showed TP53 mutation before MLL amplification. Morphologically, the leukemic cells frequently showed cytoplasmic vacuoles, bilobed nuclei, and were associated with background dyspoiesis. Immunophenotypically, 15 patients had a myeloid and 4 had myelomonocytic immunophenotype. Laboratory coagulopathies were common; 7 patients developed disseminated intravascular coagulopathy, and 3 died of intracranial bleeding. All patients were refractory to therapy; the median overall survival was 1 month, after MLL gene amplification was detected. We concluded that AML/MDS with MLL gene amplification is likely a subset of therapy-related AML/MDS or AML with myelodysplasia-related changes, associated with distinct clinicopathological features, frequent disseminated intravascular coagulopathy, a highly complex karyotype, TP53 deletion/mutation, and an aggressive clinical course.

MLL amplification in leukemia

The exact incidence of MLL amplification in myeloid malignancies is difficult to establish. In large studies, MLL amplification has been found in < 1% of AML/MDS with abnormal karyotype. Amplification of MLL gene is the second most amplified gene in AML/MDS after CMYC oncogene. In one study, MLL amplification was found in 8/27 (29%) AML cases exhibiting homogenously staining region (hsr) and double minutes (dmin). AML/MDS with MLL amplification is associated with an elderly age, a median age at presentation of 72 years, ranged from 4 to 91 years, often prior history of therapy with alkylating agents or topoisomerase II, and slight female predominance. In therapy-related MDS/AML amplification of MLL gene was found in 12% patients.

Amplification of MLL gene in a new case of acute myeloid leukemia

Case report of a translocation : Amplification of MLL gene in a new case of acute myeloid leukemia.

Segmental amplification of MLL gene associated with high expression of AURKA and AURKB genes in a case of acute monoblastic leukemia with complex karyotype

We report a case of acute monoblastic leukemia showing a jumping translocation with the MLL gene in a 17-year-old male. Classic cytogenetic and spectral karyotyping revealed a complex karyotype, and fluorescence in situ hybridization (FISH) demonstrated amplification of the MLL gene followed by translocation to chromosomes 15q, 17q, and 19q. In addition, molecular analyses showed a high expression of AURKA and AURKB genes. It is already known that overexpression of Aurora kinases is associated with chromosomal instability and poor prognosis. The formation of jumping translocations is a rare cytogenetic event and there is evidence pointing toward preferential involvement of the heterochromatin region of donor chromosomes and the telomere ends of recipient chromosomes. Jumping translocation with the MLL gene rearrangement is an uncommon phenomenon reported in leukemia cytogenetics.

Dic (17;20) (p11;q11) Preceded &lt;I&gt;MLL&lt;/I&gt; Gene Amplification in a Patient with &lt;I&gt;de novo&lt;/I&gt; Mixed-Lineage Leukemia

We report a case of acute mixed-lineage leukemia, as seen in a 65 year-old female with MLL gene amplification and biallelic loss of wild type p53 gene. The diagnosis was based on the findings that her bone marrow (BM) blasts expressed cytoplasmic CD3 (cyCD3), B-lineage antigens and myeloid antigens accompanied by clonal rearrangements of IgH gene. The BM blasts consisted of small-sized peroxidase-negative blasts (97%) and large-sized peroxidase-positive blasts (3%). The BM blasts showed a complex "karyotype," including dic(17;20) (p11;q11), -5 and add (11q23). Add (11q23) abnormality was found in sideline karyotypes as well as the stemline abnormality of dic(17;20) (p11;q11). For the p53 gene, which is located at 17p13, fluorescence in situ hybridization analysis showed the loss of one of two p53 alleles. Furthermore, polymerase chain reaction-single-strand conformation polymorphism and following nucleotide sequencing showed that the p53 gene was mutated at codon 215, leading to an amino acid substitution from Ser to Arg. For the MLL gene, southern blot analysis showed that the MLL gene locus was amplified but not rearranged at its breakpoint cluster region, which is usually rearranged in balanced translocations with many partner genes. These findings suggest that MLL gene amplification may in this case be based on the genetic instability caused by the preceding biallelic loss of the wild type p53 gene.

Double Minute Chromosome in Acute Myeloid Leukemia.

Introduction: Double minutes (dmin) are small chromatin particles that lack a centromere and represent a form of extrachromosomal gene amplification. They have been found in a variety of solid tumors but are rare in hematological malignancies. C-MYC and MLL are the most common genes amplified on the dmin in AML. Here we report a case of AML in which FISH did not demonstrate C-MYC or MLL gene amplification on the dmin.Case Report: A seventy-seven-year-old man was diagnosed with acute leukemia. Histology and flow cytometry (blasts positive for CD13, CD33, CD34, HLA-DR, CD15, CD117 and cytoplasmic MPO) were consistent with M2 AML. Chromosome analysis revealed abnormal karyotype with hypodiploidy 42–44 and loss of chromosome 5, 7,13,17,18, and Y. Structural rearrangements involving chromosomes 2,7,11,19 and 20 in addition to 2 marker chromosomes and dmin. FISH did not reveal C-MYC gene amplification. FISH did reveal MLL gene amplification, but not on the dmin. The patient received induction chemotherapy, and expired on day 14 due to cardiac complications.Discussion: Double minutes are a mechanism for upregulated oncogene expression. After the development of molecular technology, FISH, it became possible to identify the amplified gene. A previous review (Thomas et al. Double minute chromosomes in monoblastic (M5) and myeloblastic (M2) acute myeloid leukemia: two case reports and a review of literature. Am J Hematol 2004 Sep;77(1):55–61), found C-MYC to be amplified on the dmin in 25 cases, MLL was found to be amplified on the dmin in 5 cases, and only 3 cases in which neither gene was found to be amplified on the dmin. Double minutes are associated with advanced age at presentation, a more aggressive clinical course, poor outcome with therapy, and shortened survival. The survival in most cases is reported to be less than 12 months.

Oncogene amplification in transforming myelodysplasia

The MLL gene, located within band 11q23, has been shown to be involved in translocations with a large variety of reciprocal sites in both lymphoid and myeloid leukemia and has also been shown to undergo submicroscopic self-fusion/partial duplication. We report 29 patients with cytogenetic evidence of 11q23 alteration, all of which demonstrate molecular cytogenetic evidence of amplification of the MLL gene by fluorescence in situ hybridization (FISH). In all MLL cases, the patients were clinically classified as having transforming myelodysplasia (RAEB/RAEBT) or AML. An additional patient with AML was found by 24-color and gene-specific FISH to have AML1 oncogene amplification. Four patients had been previously diagnosed with cancer and had received topoisomerase II targeted drug therapy which is known to be associated with fusion transcripts involving the MLL and AML1 genes. MLL amplification appeared in various forms: an atypical banded region that bridges from 11q23 into a dicentric chromosome, expanded regions emanating from band 11q23, chromosome 11 paint-positive rings with “spoke-like” MLL amplification, and expansion at sites other than chromosome 11 (including extra markers) in the absence of one of the 11 homologues. The fluorescence pattern in most cases suggests palindromic duplication with neighboring sequences in the long arm of chromosome 11. As opposed to MYCN amplification in hsrs (homogeneously staining regions) and double minutes in neuroblastoma, amplification of MLL in most cases occurred at the site of the gene. All of our patients rapidly developed refractory AML. The frequency and clinical correlations of MLL gene amplification in leukemia will need careful follow-up, since the frequently cryptic amplification described in these cases may not generally provoke confirmatory FISH studies. The reported MLL cases represented about 1% of the total abnormal MDS/AML cases over 8 years. A common cytogenetic profile of 5 q-, −17/17 p-, −18/18 q-, and a missing or abnormal chromosome 11, may help direct appropriate follow-up studies. The MLL and the AML1 oncogenes appear to be the only oncogenes amplified at the natural site of the gene. Both genes also show a high degree of diversity of pathogenic mechanisms of leukemia evolution, including numerous reciprocal fusion genes in transformation to either AML or ALL and gain of function amplification.

Variations in MLL Amplification in a Patient with Acute Myeloid Leukemia

In a 66 years old female patient with acute myeloblastic leukemia (AML) complex chromosomal rearrangements involving 11q23 were diagnosed by G-banding and confirmed by different fluorescence in situ hybridization (FISH) techniques. The amplification of MLL gene differed in various sidelines as shown by locus specific probes for 11q23 and 11q13. Complex karyotype rearrangements involving deletions del(5)(q31) and del(7)(q31) were verified by multicolor fluorescence in situ hybridization (mFISH).