- Case report
- Open Access
Acute myeloid leukemia with t(7;21)(p22;q22) and 5q deletion: a case report and literature review
© Ji et al.; licensee BioMed Central Ltd. 2014
- Received: 12 February 2014
- Accepted: 9 March 2014
- Published: 19 March 2014
The gene RUNX1 at chromosome 21q22 encodes the alpha subunit of Core binding factor (CBF), a heterodimeric transcription factor involved in the development of normal hematopoiesis. Translocations of RUNX1 are seen in several types of leukemia with at least 21 identified partner genes. The cryptic t(7;21)(p22;q22) rearrangement involving the USP42 gene appears to be a specific and recurrent cytogenetic abnormality. Eight of the 9 cases identified in the literature with this translocation were associated with acute myeloid leukemia (AML), with the remaining case showing refractory anemia with excess blasts, type 2. Herein, we present a patient with two preceding years of leukopenia and one year of anemia prior to the diagnosis of AML, NOS with monocytic differentiation (myelomonocytic leukemia) whose conventional cytogenetics showed an abnormal clone with 5q deletion. Interphase FISH using LSI RUNX1/RUNXT1 showed three signals for RUNX1. FISH studies on previously G-banded metaphases showed the extra RUNX1 signal on the short arm of chromosome 7. Further characterization using the subtelomeric 7p probe showed a cryptic 7;21 translocation. Our case and eight previously reported leukemic cases with the t(7;21)(p22;q22) appear to share similar features including monocytic differentiation, immunophenotypic aberrancies (often with CD56 and/or CD7), and a generally poor response to standard induction chemotherapy. About 80% of these cases had loss of 5q material as an additional abnormality at initial diagnosis or relapse. These findings suggest that t(7;21) may represent a distinct recurrent cytogenetic abnormality associated with AML. The association between the t(7;21) and 5q aberrancies appears to be non-random, however the pathogenetic connection remains unclear. Additional studies to evaluate for RUNX1 partner genes may be considered for AML patients with RUNX1 rearrangement and 5q abnormalities; however knowledge of the prognostic implications of this rearrangement is still limited.
- Acute myeloid leukemia
Gene fusion and chromosomal abnormalities play vital roles in tumorigenesis, including hematologic malignancies . More than 100 fusion genes have been reported in acute myeloid leukemia (AML) . Many of these fusion genes involve the translocation of Runt-related transcription factor 1 (RUNX1), also known as acute myeloid leukemia 1 protein (AML1) . The gene RUNX1 at chromosome 21q22 encodes the alpha subunit of core binding factor (CBF), a heterodimeric transcription factor involved in the development of normal hematopoiesis. At least 21 partner genes of RUNX1 have been identified. Translocations of RUNX1 have been reported in acute lymphoblastic leukemia (ALL) [4, 5], acute myeloid leukemia (AML), and myelodysplastic syndromes (MDS). In AML, the t(8;21)(q22;q22) is the most frequent translocation involving RUNX1. In contrast, the much rare t(7;21)(p22;q22) involving a rearrangement with the USP42 gene, is cryptic, but appears to be a specific and recurrent cytogenetic abnormality.
The deletion of all or part of long arm of chromosome 5 (del(5q)) is a recurrent abnormality in AML and MDS patients. While the association between del(5q) and AML are still unclear, a deletion of 1.5 Mb region at 5q31.1 flanked by genes IL-9 and EGR-1 has been reported to be related with AML . In addition, del(5q) is mostly part of the complex karyotype in many AML cases, which makes it more difficult to reveal its significance.
In this study, we describe a new AML case with a cryptic t(7;21)(p22;q22) and chromosome 5q abnormality. The case reported here shares the common features with the few other cases reported in the literature, suggesting that the t(7;21)(p22;q22) may represent a distinct entity in AML.
The patient is a 57-year-old female who was referred for hematology consult after presenting with a two-year history of chronic leukopenia with progression to include anemia of several months duration. A bone marrow biopsy was performed, revealing approximately 24% myeloblasts by immunohistochemistry, with the blasts expressing monocytic differentiation with aberrant CD56 expression by flow cytometry. She was diagnosed with AML, and was referred to an academic center for inpatient chemotherapy and possible transplant. Following evaluation, she was placed on Revlimid therapy as opposed to induction chemotherapy for about 5 months without improvement or significant deterioration of her blood counts. She was referred to our institution to be evaluated for allogenic stem-cell transplantation. A repeat bone marrow biopsy (about 6–7 months post diagnosis) confirmed persistent AML, and the patient was started on 7 + 3 AML induction (Cytarabine 320 mg IV continuous days 1–7, Idarubicin 19 mg IV on days 3–6). A day 16 repeat bone marrow biopsy showed persistent presence of abnormal myeloblasts. Biopsy about 6 weeks following induction therapy showed remission with no excess or abnormal myeloblasts. She completed consolidation chemotherapy with high-dose cytarabine (3 gm/m2 IV q 12 hours on days 1, 3, 5 for 6 doses), and recently had a successful allogenic stem-cell transplant.
Particle smears and touch preparations were prepared upon receipt of specimen, air dried, and stained with Wright-Giemsa. Trephine biopsy and aspirate clot sections were fixed in B5 and buffered formalin, respectively. Following fixation, tissues were paraffin-embedded, and 4-μm thick sections were cut and stained with hematoxylin-eosin.
A WBC suspension is created from the bone marrow aspirate sample using bulk lysing with BD Pharmlyse (ammonium chloride base) and PBS wash. 6-Color custom cocktails (FITC/PE/PerCPCy5.5/APC/APCH7/V450 fluorochrome format) for immunophenotyping were manufactured by the CTT group of Becton Dickinson. The antibody staining and fixation include a 15 minute incubation in the dark, PBS washing, and resuspension & fixation with 1% paraformaldehyde. The Becton Dickinson FACSCanto II (3-laser) flow cytometer with BD FACSDiva Software were used for event acquisition, and FCS Express Version 3.00.0821 (DeNovo Software, Los Angeles, CA) was used for analysis.
Conventional chromosome analysis was performed on bone marrow cells using standard cytogenetic techniques and G-banding. A total of 20 metaphase cells were analyzed. Karyotypes were prepared using Applied Imaging CytoVision software and described according to the guidelines of International System for Human Cytogenetic Nomenclature (ISCN, 2013) .
Fluorescence in situ hybridization (FISH)
FISH studies were performed on both interphase nuclei and previously G-banded metaphases from the patient’s bone marrow sample. Interphase FISH probes included: EGR1/D5S23-D5S721, D7S486 (7q31)/CEP 7, CEP 8 (D8Z2)/D20S108 (20q12), PML/RARA Dual Color (DC) Dual Fusion (DF), BCR/ABL DC, DF, EVI1 Tri-color (3q26), CBFB DC (16q22), MLL DC (11q23) Break Apart and RUNX1 T1/RUNX1 (ETO/AML1) DC DF probe. Metaphase FISH on previously G-banded slides included RUNX1 T1/RUNX1 (ETO/AML1) DC DF probe, TelVysion 7p, 7q and 14q probe (subtelomeric cocktail). All the probes were from Abbott Molecular (Des Plaines, Illinois 60018).
Morphology and immunophenotypic findings
Reported cases with t(7;21)(p22;q22)
56 yo, F
CR 51 days s/p induction. Completed consolidation and recently underwent unrelated SCT
Paulsson, et al. 
7 yo, M
Yes (at relapse)
Relapse at 5 years with successful re-induction
Foster, et al. 
68 yo, M
Dead at 5 years from unrelated illness
Giguère, et al. 
32 yo, M
Died of fungal infection within months of dx
Jeandidier, et al. 
Myelomonocytic vs. Monblastic/Monocytic
54 yo, M
CD2, CD7, CD22, CD56
Relapse at 23 months, DOD
33 yo, M
CR after salvage chemo and allogenic transplant, alive at 36 months
39 yo, M
Partial response to salvage chemo, dead of bacterial sepsis within months of dx
Gindina, et al. 
13 yo, M
CD7, CD56, CD71
Remission after consolidation chemo, No long-term survival data reported
Panagopoulos, et al. 
52 yo, F
In remission at nine months post dx, no long-term survival data reported
Foster, et al. 
RAEB-2 (17% blasts)
68 yo, F
Mylotarg, Daunorubici, Clofarabine
Remained in remission post maintenance chemotherapy
We compared our case with the other reported t(7;21)(p22;q22) cases (Table 1) [2, 8–11]. Of all the 9 reported t(7;21)(p22;q22) cases, eight were diagnosed as AML, and one as an MDS (RAEB-2). In all reported AML patients with t(7;21)(p22;q22) including our current case, the common features in these patients include: 1) Aberrant CD56 expression (8/9 patients) and aberrant CD7 expression (6/9 patients). No patients had expression of CD19, which is commonly seen in t(8;21) [13, 14]. 2) Myelomonocytic or monocytic differentiation was common (6/9), and 3/9 patients did not show maturation or showed minimal differentiation. 3) Patients responded poorly to the standard induction chemotherapy. 4) Eight of the 9 patients had loss of chromosome 5q at the initial diagnosis or at relapse.
CD56 expression is seen in about 25% [15, 16] of AML cases with t(8;21) (q22;q22), and is generally associated with poor prognosis . Meanwhile, CD7 is expressed in about 30% of AML cases and its positivity is linked with poor prognosis in myeloid malignancies . The t(7;21)(p22;q22) AML cases had CD56 and CD7 positive rates higher than what has been reported in general AML cases, and these patients had an overall poor response to standard chemotherapy (Table 1).
One of the genes located on chromosome 5q is ribosomal protein S14 (RPS14), which is essential for the maintenance of normal erythroid progenitor cells . Loss of chromosome 5q causes haploinsufficiency of RPS14 . Boultwood et al.  hypothesized that this haploinsufficiency may be related with failure of erythropoiesis. In our case report, the patient had a history of anemia for one year, and the karyotype showed loss of chromosome 5q. We speculate that the anemia in this patient is related with haploinsufficiency of RPS14, however, this speculation would need to be validated by further molecular testing.
As previously noted, deletion of 5q is a common cytogenetic abnormalities in 8 of the 9 patients with t(7;21)(p22;q22). The high incidence of t(7;21)(p22;q22) found together with del(5q) suggest that this combination is a non-random abnormality. Many questions need to be answered, including: Why does this combination happen with such a high frequency? What is the etiology? What is the significance of these aberrancies in relation to AML? Although a recent large scale cooperative study of 514 MDS patients showed that 5q deletion with additional cytogenetic abnormalities is a marker of poor prognosis , additional study is needed for this combination in AML. While we cannot provide further experimental evidence, we think one possibility is that two (or more) functionally redundant genes were disrupted by the t(7;21)(p22;q22) and del(5q) respectively. Subsequently, the affected cells would have lost important functions associated with drug resistance, apoptosis, and/or DNA repair.
All previous reports about the t(7;21)(p22;q22) rearrangement have detected a RUNX1-USP42 fusion protein. It is reasonable to assume that our case also has the associated RUNX1-USP42 fusion protein, although we did not pursue the exact partner of RUNX1 in this report due to the limited specimen. RUNX1 is a vital regulator of hemopoiesis . Various hemopoietic signaling molecules, growth factors, and transcription factors are regulated by RUNX1 . RUNX1 translocation is a recurrent feature in many AML and MDS patients, and numerous translocation partners have been described. RUNX1 rearrangment’s leukemogenicity lies in the retention of RUNX1’s DNA binding “Runt homology domain” (RHD) domain, and associated loss of its transactivation domain. The resultant fusion protein acts as a dominant negative inhibitor of wild-type RUNX1 in transcription activation [11, 22].
While most studies focus on RUNX1, ubiquitin specific peptidase 42 (USP42) may also play an important leukemogenic role in t(7;21)(p22;q22) cases. USP42, belonging to the ubiquitin-proteasome system (UPS), is a deubiquitinating enzyme (DUB). The process of ubiquitination and deubiquitination decides the fate of many proteins, many of which are related with cell cycle regulation, DNA repair, and differentiation. USP and the DUBs contain many potential drug targets for the treatment. USP42 itself was reported to increase the stability of p53 . We propose that RUNX1-USP42 fusion protein loses wild type USP42 function and decreases the stability of p53. Further studies to characterize the involvement of USP42 in our case were not possible due to insufficient sample.
In conclusion, we report a new case of AML with a cryptic t(7;21)(p22;q22) and chromosome 5q abnormality. To the best of our knowledge, this represents one of the few AML patients with this genetic aberrancy. Review of the literature showed that our case shares many common features with other reported cases, which suggests that t(7;21)(p22;q22) may represent a new distinct entity in AML.
Consent for publication of this case report and any accompanying images was obtained from the patient.
Sources of funding
No extramural funds were used to support this project.
- Mitelman F, Johansson B, Mertens F: The impact of translocations and gene fusions on cancer causation. Nat Rev Cancer 2007, 7: 233–245. 10.1038/nrc2091PubMedView ArticleGoogle Scholar
- Giguere A, Hebert J: Microhomologies and topoisomerase II consensus sequences identified near the breakpoint junctions of the recurrent t(7;21)(p22;q22) translocation in acute myeloid leukemia. Genes Chromosomes Cancer 2011, 50: 228–238.PubMedGoogle Scholar
- Ferrando AA, Look AT: Clinical implications of recurring chromosomal and associated molecular abnormalities in acute lymphoblastic leukemia. Semin Hematol 2000, 37: 381–395. 10.1016/S0037-1963(00)90018-0PubMedView ArticleGoogle Scholar
- Golub TR, Barker GF, Bohlander SK, Hiebert SW, Ward DC, Bray-Ward P, Morgan E, Raimondi SC, Rowley JD, Gilliland DG: Fusion of the TEL gene on 12p13 to the AML1 gene on 21q22 in acute lymphoblastic leukemia. Proc Natl Acad Sci USA 1995, 92: 4917–4921. 10.1073/pnas.92.11.4917PubMed CentralPubMedView ArticleGoogle Scholar
- Mikhail FM, Coignet L, Hatem N, Mourad ZI, Farawela HM, El Kaffash DM, Farahat N, Nucifora G: A novel gene, FGA7, is fused to RUNX1/AML1 in a t(4;21)(q28;q22) in a patient with T-cell acute lymphoblastic leukemia. Genes Chromosomes Cancer 2004, 39: 110–118. 10.1002/gcc.10302PubMedView ArticleGoogle Scholar
- Giagounidis AA, Germing U, Aul C: Biological and prognostic significance of chromosome 5q deletions in myeloid malignancies. Clin Cancer Res 2006, 12: 5–10. 10.1158/1078-0432.CCR-05-1437PubMedView ArticleGoogle Scholar
- Shaffer L, McGowan-Jordan J, Schmid M (Eds): ISCN (2013): An International System for Human Cytogenetic Nomenclature. BAsel: S. Karger; 2013.Google Scholar
- Paulsson K, Bekassy AN, Olofsson T, Mitelman F, Johansson B, Panagopoulos I: A novel and cytogenetically cryptic t(7;21)(p22;q22) in acute myeloid leukemia results in fusion of RUNX1 with the ubiquitin-specific protease gene USP42. Leukemia 2006, 20: 224–229. 10.1038/sj.leu.2404076PubMedView ArticleGoogle Scholar
- Foster N, Paulsson K, Sales M, Cunningham J, Groves M, O’Connor N, Begum S, Stubbs T, McMullan DJ, Griffiths M, Pratt N, Tauro S: Molecular characterisation of a recurrent, semi-cryptic RUNX1 translocation t(7;21) in myelodysplastic syndrome and acute myeloid leukaemia. Br J Haematol 2010, 148: 938–943. 10.1111/j.1365-2141.2009.08039.xPubMedView ArticleGoogle Scholar
- Jeandidier E, Gervais C, Radford-Weiss I, Zink E, Gangneux C, Eischen A, Galoisy AC, Helias C, Dano L, Cammarata O, Jung G, Harzallah I, Guerin E, Martzolff L, Drenou B, Lioure B, Tancredi C, Rimelen V, Mauvieux L: A cytogenetic study of 397 consecutive acute myeloid leukemia cases identified three with a t(7;21) associated with 5q abnormalities and exhibiting similar clinical and biological features, suggesting a new, rare acute myeloid leukemia entity. Cancer Genet 2012, 205: 365–372. 10.1016/j.cancergen.2012.04.007PubMedView ArticleGoogle Scholar
- Panagopoulos I, Gorunova L, Brandal P, Garnes M, Tierens A, Heim S: Myeloid leukemia with t(7;21)(p22;q22) and 5q deletion. Oncol Rep 2013, 30: 1549–1552.PubMed CentralPubMedGoogle Scholar
- Huret JL: t(7;21)(p22;q22). Atlas Genet Cytogenet Oncol Haematol October 2007. http://AtlasGeneticsOncology.org/Anomalies/t0721p22q22ID1449.html
- Andrieu V, Radford-Weiss I, Troussard X, Chane C, Valensi F, Guesnu M, Haddad E, Viguier F, Dreyfus F, Varet B, Flandrin G, Macintyre E: Molecular detection of t(8;21)/AML1-ETO in AML M1/M2: correlation with cytogenetics, morphology and immunophenotype. Br J Haematol 1996, 92: 855–865. 10.1046/j.1365-2141.1996.415954.xPubMedView ArticleGoogle Scholar
- Khoury H, Dalal BI, Nevill TJ, Horsman DE, Barnett MJ, Shepherd JD, Toze CL, Conneally EA, Sutherland HJ, Hogge DE, Nantel SH: Acute myelogenous leukemia with t(8;21)–identification of a specific immunophenotype. Leuk Lymphoma 2003, 44: 1713–1718. 10.1080/1042819031000116698PubMedView ArticleGoogle Scholar
- Chen SW, Li CF, Chuang SS, Tzeng CC, Hsieh YC, Lee PS, Chen CH, Huang WT, Hwang WS, Tsao CJ: Aberrant co-expression of CD19 and CD56 as surrogate markers of acute myeloid leukemias with t(8;21) in Taiwan. Int J Lab Hematol 2008, 30: 133–138. 10.1111/j.1751-553X.2007.00913.xPubMedView ArticleGoogle Scholar
- Raspadori D, Damiani D, Lenoci M, Rondelli D, Testoni N, Nardi G, Sestigiani C, Mariotti C, Birtolo S, Tozzi M, Lauria F: CD56 antigenic expression in acute myeloid leukemia identifies patients with poor clinical prognosis. Leukemia 2001, 15: 1161–1164. 10.1038/sj.leu.2402174PubMedView ArticleGoogle Scholar
- Rohrs S, Scherr M, Romani J, Zaborski M, Drexler HG, Quentmeier H: CD7 in acute myeloid leukemia: correlation with loss of wild-type CEBPA, consequence of epigenetic regulation. J Hematol Oncol 2010, 3: 15. 10.1186/1756-8722-3-15PubMed CentralPubMedView ArticleGoogle Scholar
- Ebert BL, Pretz J, Bosco J, Chang CY, Tamayo P, Galili N, Raza A, Root DE, Attar E, Ellis SR, Golub TR: Identification of RPS14 as a 5q- syndrome gene by RNA interference screen. Nature 2008, 451: 335–339. 10.1038/nature06494PubMed CentralPubMedView ArticleGoogle Scholar
- Boultwood J, Pellagatti A, McKenzie AN, Wainscoat JS: Advances in the 5q- syndrome. Blood 2010, 116: 5803–5811. 10.1182/blood-2010-04-273771PubMedView ArticleGoogle Scholar
- Mallo M, Cervera J, Schanz J, Such E, Garcia-Manero G, Luno E, Steidl C, Espinet B, Vallespi T, Germing U, Blum S, Ohyashiki K, Grau J, Pfeilstocker M, Hernandez JM, Noesslinger T, Giagounidis A, Aul C, Calasanz MJ, Martin ML, Valent P, Collado R, Haferlach C, Fonatsch C, Lubbert M, Stauder R, Hildebrandt B, Krieger O, Pedro C, Arenillas L, et al.: Impact of adjunct cytogenetic abnormalities for prognostic stratification in patients with myelodysplastic syndrome and deletion 5q. Leukemia 2011, 25: 110–120. 10.1038/leu.2010.231PubMedView ArticleGoogle Scholar
- Okuda T, van Deursen J, Hiebert SW, Grosveld G, Downing JR: AML1, the target of multiple chromosomal translocations in human leukemia, is essential for normal fetal liver hematopoiesis. Cell 1996, 84: 321–330. 10.1016/S0092-8674(00)80986-1PubMedView ArticleGoogle Scholar
- Laufer EM, Winkens MH, Narula J, Hofstra L: Molecular imaging of macrophage cell death for the assessment of plaque vulnerability. Arterioscler Thromb Vasc Biol 2009, 29: 1031–1038. 10.1161/ATVBAHA.108.165522PubMedView ArticleGoogle Scholar
- Hock AK, Vigneron AM, Carter S, Ludwig RL, Vousden KH: Regulation of p53 stability and function by the deubiquitinating enzyme USP42. EMBO J 2011, 30: 4921–4930. 10.1038/emboj.2011.419PubMed CentralPubMedView ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.