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 Table of Contents  
LETTER TO THE EDITOR
Year : 2017  |  Volume : 42  |  Issue : 4  |  Page : 172-174

Isolated trisomy 6 cytogenetic abnormalities in acute myeloid leukaemia: a case report


1 Department of Pathology, American Oncology Institute, Hyderabad, India
2 Department of Haemato-Oncology, American Oncology Institute, Hyderabad, India

Date of Submission24-Jul-2017
Date of Acceptance19-Oct-2017
Date of Web Publication9-Feb-2018

Correspondence Address:
Vikranth Varma
Department of Pathology, Ampath, Hyderabad-500019
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ejh.ejh_33_17

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How to cite this article:
Varma V, Aribandi A, Chelmeda S. Isolated trisomy 6 cytogenetic abnormalities in acute myeloid leukaemia: a case report. Egypt J Haematol 2017;42:172-4

How to cite this URL:
Varma V, Aribandi A, Chelmeda S. Isolated trisomy 6 cytogenetic abnormalities in acute myeloid leukaemia: a case report. Egypt J Haematol [serial online] 2017 [cited 2018 Jun 25];42:172-4. Available from: http://www.ehj.eg.net/text.asp?2017/42/4/172/225087




  Introduction Top


Identification of cytogenetic abnormalities plays an important role in the diagnosis and prognosis of leukaemias. About 50–55% of acute myeloid leukaemia (AML) are characterised by the presence of specific, balanced chromosome aberrations and abnormalities in the genesis of specific fusion genes. Numerical aberrations as the only karyotypic anomalies, including single or multiple losses or gains, are found in ∼15% of all cytogenetically abnormal haematological malignancies [1]. Among them, isolated trisomy of chromosome 6 is a rare abnormality. It is difficult to determine the prognostic significance of trisomy 6 in AML because of the reduced clinical publications [2]. Here, we present a case of AML with karyotypic abnormality of trisomy 6.


  Case report Top


A 44-year-old man reported to the Department of Haematology, American Oncology Institute, Hyderabad, India, with complaints of generalised weakness, low-grade fever, cough and fatigue of 3 weeks duration. He was found to be purpuric and had received single-donor adult dose platelet transfusion during this period. On general examination, he had anaemia, fever and bone pain. There was no lymphadenopathy or bleeding manifestations. On systemic examination, he had fine crepitations over the bilateral basal lung regions without organomegaly.

A full blood count has shown a haemoglobin level of 10.3 g%, total leucocyte count of 103.2×103/μl and a platelet count of 6×103/μl. Peripheral smear showed 73% blasts of myeloid cell morphology. Bone marrow aspirates and touch preparation showed hypercellular marrow filled with myeloblasts and 15% mature myeloid forms. On cytochemistry, blasts were positive for myeloperoxidase, nonspecific esterase and negative for periodic acid–Schiff and acid phosphatase. Bone marrow biopsy showed 100% cellularity with diffuse replacement by blasts.

Immunophenotyping was performed by four-colour flow cytometry using a BD FACS (BD Biosciences, San Jose, CA, USA). Gated blast populations of cells were positive for CD13, CD33, CD117, CD34, Human Leucocyte Antigen-antigen D related (HLA-DR), cytoplasmic myeloperoxidase and CD15. Bone marrow morphology, cytochemistry and immunophenotyping were consistent with the diagnosis of AML-M2.

Cytogenetic analysis was performed on unstimulated bone marrow aspirate cultures with or without colcemid using the standard cytogenetic technique [3]. GTG banding (G-bands by trypsin using Giemsa) was analysed using an automated karyotyping system (MetaSystems GmbH, Altlubheim, Germany). The karyotype was reported according to the 2016 International System of Human Cytogenetic Nomenclature [4]. The 20 metaphases that were revealed showed the presence of a neoplastic clone characterised by gain of an additional copy of chromosome 6 in five metaphases, whereas the remaining 15 metaphases were normal: 47,XY,+6[05]46,XY(15) ([Figure 1]).
Figure 1 GTG banding 47,XY,+6.

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He was started on 7+3 induction with cytarabine at a dose of 100 mg/m2/day as a continuous infusion over 24 h for 7 days and daunorubicin at 60 mg/m2/day as a short infusion for 3 days. After the first induction, bone marrow on day 14 revealed persistence of blasts (21%). Hence, he was given a second induction with mitoxantrone and high-dose cytarabine (HAM). During treatment with HAM, the patient developed septicaemia with respiratory dysfunction and bilateral fungal pneumonia, for which he was treated appropriately. Bone marrow studies were repeated and he was found to be in remission. He then received two more cycles of high-dose cytarabine as postremission therapy. He recovered uneventfully, and is presently being followed up on a regular basis. Now he was planned for allogenic stem cell transplantation.


  Discussion Top


In India, AML accounts for ∼20% of acute leukaemia in children and 80% of acute leukaemia in adults. The incidence of AML progressively increases with age and in individuals over the age of 65 years, the incidence is ∼30 times the incidence of AML in children. Whole chromosome gains or loses are frequently found in haematological malignancies either solitary or superimposed type [1]. The mechanism by which trisomies leads to leukemogenesis are gene dosage effect as a result of the trisomy and cryptic gene rearrangement or mutation of the genes on the other chromosomes [5].

According to the literature, only 14 cases of AML and five cases of myelodysplastic syndrome have been reported with isolated trisomy 6. Commonly seen in patients with aplastic anaemia are myelodysplastic syndrome, AML, lymphoblastic transformation of chronic myeloid leukaemia and chronic myeloproliferative disorders. Most of the patients had hypocellular marrow with erythroid dysplasia or they proceeded from aplastic anaemia to AML [6],[7]. In contrast to this, our patient presented with a short duration of fatigue, purpura, and fever and was found to have hypercellular bone marrow with replacement of normal marrow elements by blasts.

In our case, blasts show positivity for HLA-DR and CD34, similar to previous cases, which indicates the primitive nature of the blasts [8]. Response to treatment was also poor as our patient failed to respond to the first induction with persistence of blasts in the marrow at day 14. However, our patient went into remission with the second induction.

The role of trisomy 6 as the sole cytogenetic abnormality is not clear, because of the limited number of cases reported in the literature, but from the data available, it is likely that this clonal cytogenetic abnormality is associated with the primitive nature of blasts and poor response to treatment [1],[9]. More studies are required to ascertain the role of trisomy 6 in the development of leukaemia as well as in the prognosis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Mohamed AN, Varterasian ML, Dobin SM, McConnell TS, Wolman SR, Rankin C et al. Trisomy 6 as a primary karyotypic aberration in hematologic disorders. Cancer Genet Cytogenet 1998; 106:152–155.  Back to cited text no. 1
    
2.
Choi J, Song J, Kim SJ, Choi JR, Kim SJ, Min YH et al. Prognostic significance of trisomy 6 in an adult acute myeloid leukemia with t(8;21). Cancer Genet Cytogenet 2010; 202:141–143.  Back to cited text no. 2
    
3.
Korf BR. Cancer genetics. In: Dracopoli NC, Haines JL, Korf BR, Moir DT, Morton CC, Seidman CE et al. editors. Current protocols in human genetics. New York: John Wiley & Sons; 1994. 4.0.1-4.1.19.  Back to cited text no. 3
    
4.
Gonzalez Garcia JR, Meza-Espinoza JP. Use of the International System for Human Cytogenetic Nomenclature (ISCN). Blood 2006; 108:3952–3953.  Back to cited text no. 4
    
5.
McCullough SJ, Neat MJ, Power M, O’Marcaigh AO. Trisomy 6 in a child with acute megakaryoblastic leukemia (AML-M7). Cancer Genet Cytogenet 2004; 154:190–192.  Back to cited text no. 5
    
6.
Ma ESK, Wan TSK. +6 or trisomy 6. Atlas Genet Cytogenet Oncol Haematol 2004; 8:253–254.  Back to cited text no. 6
    
7.
Kelly MJ, Meloni-Ehrig AM, Manley PE, Altura RA. Poor outcome in a pediatric patient with acute myeloid leukemia associated with a variant t(8;21) and trisomy 6. Cancer Genet Cytogenet 2009; 189:48–52.  Back to cited text no. 7
    
8.
Moormeier JA, Rubin CM, Le Beau MM, Vardiman JW, Larson RA, Winter JN. Trisomy 6: a recurring cytogenetic abnormality associated with marrow hypoplasia. Blood 1991; 77:1397–1398.  Back to cited text no. 8
    
9.
Jonveaux P, Fenaux P, Berger R. Trisomy 6 as the sole chromosome abnormality in myeloid disorders. Cancer Genet Cytogenet 1994; 74:150–152.  Back to cited text no. 9
    


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