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Revista Brasileira de Hematologia e Hemoterapia

Print version ISSN 1516-8484On-line version ISSN 1806-0870

Rev. Bras. Hematol. Hemoter. vol.39 no.4 São Paulo Oct./Dec. 2017

http://dx.doi.org/10.1016/j.bjhh.2017.06.001 

Images in Clinical Hematology

Molecular genetic techniques for gains and losses of genomic material in a case of acute myeloid leukemia

Mauren Fernanda Moller dos Santosa  * 

Camila Clozato Laraa 

Elvira Deolinda Rodrigues Pereira Vellosoa  b 

aSociedade Beneficente Israelita Brasileira Albert Einstein (SBIBAE), São Paulo, SP, Brazil

bFaculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, SP, Brazil

A 67-year-old male presented with a four-week history of weakness. The complete blood count showed: hemoglobin: 5.1 g/dL, leukocytes 182.55 × 103/µL (23% blasts and 34% monocytes) and platelets: 31 × 109/L. A bone marrow aspirate showed 50.4% of myeloid myeloperoxidase (MPO)-blast cells and 42.4% of dysplastic granulocytic-monocytic series, with alpha-naphthyl acetate esterase positivity in 30% of total nucleated cells. Flow cytometry identified two distinct aberrant blasts (CD4-CD7-CD11c-CD13-CD34-CD117-HLA-DR-cMPO+) and myeloid/monocytic (CD14-CD33-CD35-HLA-DR-CD11b+) populations. Karyotyping showed monosomy 7 and additional material in the long arm of chromosome 2 (Figure 1A). Acute myeloid leukemia (AML)-M4 (FAB classification) or AML with myelodysplasia-related changes (WHO 2008 classification) was diagnosed. Patient died two months after without response to therapy.

Figure 1 (A) Karyotype (G-band): 45,XY,add(2)(q35),-7[20]. (B) FISH (Del (7q) Deletion Probe, ref: RU-LPH 025; Cytocell, Cambridge, UK): Deletion of RELN gene (chromosome 7) in 96% of the analyzed nuclei. The absence of a green and a red signal may indicate the monosomy of the chromosome. 

Apart from karyotyping, other molecular genetic techniques can detect gains and losses of genomic material.1-3 In this case, the additional material in chromosome 2 was elucidated and chromosome 7 monosomy was confirmed using fluorescence in situ hybridization, multiplex ligation-dependent probe amplification and single nucleotide polymorphism-array methodologies (Figures 1B,2A and B).

Figure 2 (A) MLPA with SALSA MLPA probemix P144-A2 (above) and P145-A2 (below) kits (MRC-Holland, Amsterdam, The Netherlands). Dosage quotient of the patients' probes in relation to a control group. Probes positioned below the 0.65 limit indicate deletion; probes positioned above the 1.35 limit indicate duplication. Probes in red indicate monosomy 7 (deletion of all probes of chromosome 7) and probes in black are normal for the other chromosomes studied in these kits. (B) SNP-A (CytoScanHD Array; Affymetrix, Santa Clara, USA): Diagrams generated by ChAS (Affymetrix) for chromosome 2 (above) and chromosome 7 (below). In "Copy number state", line in 2.00 indicates a normal copy number (diploid), line in 1.00 indicates a deletion and line in 3.00 indicates a duplication/gain. Lines with intermediate values between 1.00 and 2.00; 2.00 and 3.00 indicate mosaicism. In "Allele Difference", three lines indicate a normal genotype (AA, AB and BB alleles), two lines indicate deletion (A and B alleles) or loss of heterozygosity (AA and BB alleles) and four lines indicate duplication (AAA, AAB, ABB and BBB alleles). SNP-A revealed the result arr[hg19] 2p25.3p16.2(12770_54276429)x3[0.8],2q35q37.3 (219576639_242783384)x1,(7)x1 where there was a partial duplication of the short arm of chromosome 2 (A and C), presenting clonal mosaic data of the duplicated region in 80% of the cells, and partial deletion of the long arm of chromosome 2 (B and D). This result can explain add (2) (q35) present in the karyotype, indicating the origin of the additional material. In addition, the monosomy of chromosome 7 was confirmed. 

References

1 Duttaa UR. Precision in chromosome identification with leads in molecular cytogenetics: an illustrated review. J Pediatr Genet. 2014;3(1):1-7. [ Links ]

2 Shen Y, Wu BL. Designing a simple multiplex ligation-dependent probe amplification (MLPA) assay for rapid detection of copy number variants in the genome. J Genet Genomics. 2009;36(4):257-65. [ Links ]

3 Tiu RV, Gondek LP, O'Keefe CL, Huh J, Sekeres MA, Elson P, et al. New lesions detected by single nucleotide polymorphism array-based chromosomal analysis have important clinical impact in acute myeloid leukemia. J Clin Oncol. 2009;27(31):5219-26. [ Links ]

Received: January 30, 2017; Accepted: June 26, 2017

*Corresponding author at: Av. Albert Einstein, 627/701, 05651-901 São Paulo, SP, Brazil. E-mail address: mauren.santos@einstein.br (M.F. Santos).

Conflicts of interest

The authors declare no conflicts of interest.

Creative Commons License This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivative License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium provided the original work is properly cited and the work is not changed in any way.