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Archived Comments for: A novel five-way translocation t(7;11;9;22; 9 )(q22;q13;q34;q11.2;q34) involving Ph chromosome in a patient of chronic myeloid leukemia: a case report

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  1. Complex translocation versus independent abnormalities in chronic myeloid leukemia

    Juan Ramon Gonzalez Garcia, Instituto Mexicano del Seguro Social

    18 June 2012

    Reyna Lucia Barajas Torres and Juan Ramon Gonzalez Garcia.
    Division de Genetica, Centro de Investigacion Biomedica de Occidente, Instituto Mexicano del Seguro Social. Guadalajara, Jalisco, Mexico. reyna_bio@hotmail.com, jrgg_gene@hotmail.com

    To the editor: Yokota et al. [1] reported a complex rearrangement in a patient with chronic myeloid leukemia (CML). Firstly, these authors established by G-banding the presence of two independent translocations t(7;11;9)(q22;q13;q34) and t(9*;22)(q34;q11.2). Then, the authors interpreted their fluorescence in situ hybridization (FISH) results with the LSI BCR/ABL ES Dual Color Translocation Probe Set (Vysis, Inc.) as a five-way translocation t(7;11;9;22;9*)(q22;q13;q34;q11.2;q34). However, the hypothesis of two independent translocations cannot be excluded with these FISH findings. That is, the standard t(9*;22) with deletion of 5¿ ABL sequences (including ASS gene) will render a FISH pattern of 1 green-red fused signal on the der(22) and no signal on the der(9*); additionally, the independent three-way translocation t(7;11;9)(q22;q13;q34) with the breakpoint upstream from 5¿ ABL gene but downstream from 3¿ or within the ASS gene complete the observed pattern of signals, namely, a faint red signal on the der(9)t(9;11) and a brighter signal on the der(7)t(7;22). A FISH study with LSI BCR/ABL + 9q34 Tricolor, Dual Fusion Translocation probe (Vysis, Inc.) could be the best option to test this hypothesis since this approach may let to visualise the putative 5¿ ABL deletion.
    There are at least other eight reported CML cases with a five-way translocation additional to those included in the table 1 [1]. They are 46,XX,t(1;22;9;5;3)(p32;q11;q34;q12;p13) (case 2) [2]; t(4;5;7;9;22)(q21;p13;p12;q34;q11) (case 35) [3]; t(6;10;9;9;22)(q24;p15;p13;q34;q11) (case 1) [4]; t(1;20;9;22;4)(q42;q12;q34;q11;q12) (case 1) [5]; t(6;9;22;11;20)(p11;q34;q11;q13;q11) (case 9) [6]; and, t(3;9;22;14;17)(p22;q34;q11;q13;q12); t(9;22;12;17;17)(q34;q11;q15;q11;q23); and t(1;22;9;15;1)(q21;q11;q34;q22;q21) (cases 9, 31, and 62, respectively) [7].
    It is really important to establish the correct karyotype in order to avoid future misinterpretations and wrong citations. An example of this is the patient # 15 reported by Bennour et al. [8] which is registered in an important public database [9] as having the complex karyotype 46,XX,t(1;1;2;9;12;13;22)(q24;q31;p21;q34;p12;p12;q11). According to their FISH studies such abnormality had to be settled as 46,XX,t(1;2),t(1;9;22),t(12;13) showing the occurrence of three independent translocations rather than a complex rearrangement. This mistake misleads the knowledge and hinders the understanding of the CML etiopathology.
    Endnotes
    *The editorial system did not allow to underline this character as recommended by the International System for Human Cytogenetic Nomenclature (2009).
    The original karyotype of case 31 in reference 7 was amended according to the breakpoint description.
    References
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    Competing interests

    The authors declare that they have no competing interests.

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