Rearrangement of three chromosomes (nos. 2,8, and 21) in acute myeloblastic leukemia. Evidence for more than one specific event

Molecular cytogenetic investigations in a novel complex variant of t(8;21)(q22;q22) with ins(15;21)(q15;q22.2q22.3) in a patient with AML-M2 subtype

Acute myeloid leukemia (AML) is a clinically and molecularly heterogeneous disease characterized by the aberrant proliferation of myeloid stem cells, reduced apoptosis and blockage in cellular differentiation. The present report describes the results of hematological, cytogenetic, and fluorescence in situ hybridization (FISH) analysis in a 25-year-old man diagnosed with AML-M2. Cytogenetic as well as FISH analysis revealed a complex translocation involving four chromosomes, with the karyotype 45,-Y,der(X)t(X;8)(p21;q22),der(8)t(8;21)(q22;q22),ins(15;21)(q15;q22.2q22.3),der(21)t(8;21)(q22;q22). The breakpoints at 8q22 and 21q22 suggested a rearrangement of the RUNX1T1 (alias ETO) and RUNX1 (previously AML1) genes, respectively. Using a dual-color FISH test with RUNX1T1 and RUNX1 probes, we demonstrated an RUNX1/RUNX1T1 fusion signal on the derivative chromosome 8, establishing this translocation as a novel complex variant of t(8;21)(q22;q22).

A variant t(8;10;21) in a patient with pathological features mimicking atypical chronic myeloid leukemia

We report the case of an 11-year-old girl who was initially diagnosed with a chronic myeloproliferative disorder, possibly chronic myelogenous leukemia (CML), based on laboratory and blood and marrow morphological findings. The patient's high leukocyte count did not respond to hydroxyurea, a standard initial therapy for CML. Chromosomal analysis revealed that the patient did not have t(9;22), but a complex t(8;10;21)(q22;q24;q22), a variant of t(8;21). The treatment regime was switched to an acute myeloid leukemia (AML) protocol; the patient responded well and is now in remission. This case demonstrates again that routine clinical cytogenetic analysis plays an important role in the clinical diagnosis, guidance of treatment, and prognostication in hematological disorders.

t(8;21;8)(p23;q22;q22): a new variant form of t(8;21) translocation in acute myeloblastic leukemia with maturation

The complex variants of t(8;21) involving chromosomes 8 and 21 as well as a variable chromosome account for 1.1-5% of acute myeloid leukemia (AML) patients. This paper reports a case of AML-M2 with t(8;21;8) translocation for the first time. The patient was a female, aged 47 years. Her myelogram was compatible with AML-M2. Chromosome study using R-banding technique revealed a karyotype 46, XX, t(8;8)(p23;q22). Dual-color FISH assay with two probes P1 164(green signal) and YAC 225B8 (red signal) both of which closely located on the 8q showed that one yellow signal consisting of a green signal and a red signal and one red signal appeared on the long and the short arm of the same der(8) chromosome, respectively, further confirming this translocation occurred between both homologous chromosomes 8. RT-PCR analysis detected the AML1/ETO fusion transcript in our patient, thus indicating that this chromosomal aberration was, in fact, a complex three-way rearrangement t(8;21;8)(p23;q22;q22). In conclusion, combining conventional karyotype, FISH or RT-PCR analyses is a rational strategy for identification of the complex variants of t(8;21) translocation.

New variant translocation (8;20)(q22;q13) in acute myelocytic leukemia

A new variant translocation, (8;20)(q22;q13) in a patient with acute myelocytic leukemia (AML) M2 is reported. As far as we know, this is the second case of the t(8;20) in de novo AML. Further studies are required to clarify the key event leading to the development of AML-M2.

Cytogenetic survey of 53 Moroccan patients with acute myeloblastic leukemia

We present a cytogenetic survey of chromosome aberrations for 53 Moroccan patients with acute myeloblastic leukemia (AML). Our 53 patients were 2 to 70 years old with 31 men and 22 women. The cytogenetic study was performed with the following three methods: first, relative proportion of normal (N) or abnormal (A) metaphases; second, presence of specific or random abnormalities; and third, karyotype complexity. Among 36 patients (67%) with a chromosomal abnormality, 18 (34%) showed a specific aberration. We have found t(9;22) in three patients (5%), chromosome 5 or 7 abnormality in six (11%), del(11)(q23) in three (6%), +21 in four (8%), and +8 in two (4%). Specific translocations associated with FAB type were found: t(8;21) with AML2 in 12 patients (23%) and t(9;11) with AML5 in one (2%). Rare abnormalities were also found: one patient with t(7;21) associated with AML2 and another patient with r(1) ring associated with AML1. We concluded that our study in a Moroccan population confirmed the relation between some specific abnormalities and the FAB classification. We have found a higher incidence for t(8;21) than usually described. Finally, we have identified chromosomal abnormalities t(7;21)(q22;p11) and r(1), rarely described before.

Variant t(8;21) rearrangements in acute myeloblastic leukemia of childhood

In a collaborative cytogenetic analysis of blast cells from 638 children with acute myeloid leukemia, 74 (11.6%) of the patients had the typical t(8;21)(q22;q22), while seven (1.1%) had complex variant translocations also involving 8q22 and 21q22 as well as a variable chromosome. In each case with a complex rearrangement, the myeloid leukemic cells contained Auer rods and were classified as M2 in the French-American-British (FAB) system. These seven children had a median age of 14 years (range, 7.3-18.9 years), a median initial leukocyte count of 9.1 x 10(9)/L (range, 2.5-142.2 x 10(9)/L), and have survived leukemia free for a median of 23 months (1-41 months) after attaining complete remission. The variable chromosomes in these seven cases--1, 2, 7, 12, 13, 15, and 17--appeared to be randomly involved. The clinico-biologic features of our cases with a variant t(8;21) are consistent with those of the published cases with the standard t(8;21), and support the hypothesis that the critical genetic alteration produced by the t(8;21) is located on the derivative 8.

Variant complex translocation t(8;15;21) in acute myeloblastic leukemia (M2) associated with bilateral chloroma

Complex translocation t(8;15;21)(q22;q21;q22) in a 9-year-old female with acute myeloblastic leukemia (M2) with bilateral chloroma is described. This particular variant type of translocation in M2 type is rare. The importance of variant translocation in defining the critical segment on the chromosomes responsible for phenotypic expression of the disease is emphasized.

Translocation (8;21) and its variants in acute nonlymphocytic leukemia. The relative importance of chromosomes 8 and 21 to the genesis of the disease

Chromosome analysis was performed in 25 patients with acute nonlymphocytic leukemia (ANLL), mostly of the M2 type. Eighteen had the standard translocation, t(8;21)(q22;q22), four had complex translocations involving 1p36, 11p13, 17p11, and 17p23, respectively, with chromosomes 8 and 21, and the remaining three patients had simple translocations, one with t(3;21)(p14;q22) and two with t(16;21)(p11;q22), without involving chromosome 8. Chromosome abnormalities additional to t(8;21) and its variants that were most frequently observed were -X, -Y, and del(9). Complex translocations are thought to be derived from the standard translocation and to be essentially similar in nature. The finding that chromosome 21 was involved in all of the standard, simple, and complex translocations, and that chromosome 8 was not involved in simple variants suggest a greater weight of chromosome 21 in the relative importance of the two chromosomes to the genesis of ANLL.

Translocation 5;21 and interstitial deletion of chromosome 7 in a case of chronic myelomonocytic leukemia

We report a case of chronic myelomonocytic leukemia with a translocation involving chromosome 5 and 21, namely, t(5;21)(q35.3;q22.1), and an interstitial deletion of the long arm of chromosome 7. High-resolution analysis at the 900-band stage has shown that the lesion in chromosome 7 is an interstitial deletion involving loss of the segments q22-q35 of the long arm of chromosome 7 and retaining the telomere.

Duplication of one of the products of the t(8;21) translocation in a patient with refractory anemia with excess blasts in transformation

A 34-year-old man with refractory anemia with excess blasts in transformation is reported, having a t(8;21) translocation and a duplication of one of the products, der(21). The duplicated product had not been observed at presentation in malignant disease, as far as we are aware; thus, the findings are discussed with regard to this case and other possible smoldering leukemias. The diagnostic use of cytogenetics is also considered.

New variant translocation (1;8;21) in a case of acute myeloblastic leukemia (M2)

A new translocation involving chromosome #1, #8, and #21 in a patient with type M2 acute myeloblastic leukemia is reported. The breakpoint of #1 in this case was at band p13 and differed from that in two previously reported cases of t(1;8;21) involving the long arm of #1. A key event leading to the development of the M2 phenotype appears to be a break at band q22 of #8 with associated translocation of the terminal end of the long arm of #21.

Two cases of acute myeloblastic leukemia (M2 type) with karyotypes 45X,-X,t(6;8)(q27;q22),inv(9) and 46,XY,t(8;21)(q22;q22),del(9)(q22)

Two patients with acute myelogenous leukemia (AML) are described. The first case is that of a patient with AML who had a low leukocyte alkaline phosphatase level associated with a variant (6;8)(q27;q22) translocation, coupled with loss of an X chromosome in bone marrow and unstimulated blood cells. The second case is that of an AML patient in whom the karyotype of the leukemic cells at the time of diagnosis was 46,XY,t(8;21)(q22;q22),del(9)(q22); at relapse, the patient acquired an additional chromosome #19. The lack of involvement of chromosome #21 in the first case, as well as the occurrence of an abnormality of chromosome #9, in addition to the t(8q-;21q+) in the second case are discussed with reference to the character of the possible specific chromosomal events in patients with type M2 AML.

Variant translocation t(8;21;15) in an acute myeloblastic leukemia with phenotypic differential evolution

A new case of a variant form of the translocation (8;21) in an AML-M2, including in addition involvement of chromosome #15 is reported. The selection of two abnormal lines, probably resulting from two successive rearrangements of the (8;15) translocated segment, is observed. It is suggested that these rearrangements change the cellular morphology and seem to play a part similar to additional autosomal abnormalities in the course of the disease, such as those found in CML.

An unusual translocation, t(3;8), and deletion of chromosome 21 in acute myeloid leukemia

This report describes a case of acute myeloid leukemia (AML) in which there was an unusual karyotypic abnormality involving chromosomes #3, #8, and #21. The clinical and hematologic features are described and cytogenetic findings are discussed in relation to previously reported variants of the translocation t(8;21) in AML. The breakpoint at 8q22 is a consistent feature in these cases.

A variant 8;21 translocation in acute myeloblastic leukemia

A three-way rearrangement involving chromosomes 1, 8, and 21 was observed in bone marrow cells from a female with acute myeloblastic leukemia, subtype M2 (AML-M2). The translocation break points in chromosomes 8 and 21 were identical to those found in the standard t(8;21) that is associated with this disease type. A review of this and four previously reported cases involving variant 8;21 translocations indicates that a consistent pattern of exchange may be involved in these complex rearrangements even though the third chromosome affected may differ.