Molecular cytogenetic analysis of -7/7q- abnormalities in patients with myeloid malignancies / 中华医学遗传学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To accurately evaluate the incidence of -7/7q- abnormality in acute myeloblastic leukemia (AML) and myelodysplastic syndrome (MDS) patients and investigate the value of fluorescence in situ hybridization (FISH) technique in the detection and identification of -7 and 7q abnormality.</p><p><b>METHODS</b>A FISH assay was performed to analyze 70 AML/MDS patients who had received conventional cytogenetic analysis (CCA). The dual color probes CEP 7 labeled by SpectrumGreen and D7S486 (locus at 7q31) labeled by SpectrumOrange were used.</p><p><b>RESULTS</b>The incidence of -7/7q- in AML and MDS patients was 4.51% (31 out of 687 cases) and 5.71% (28 out of 490 cases), respectively, and was 5.68% and 10.29% in these patients with abnormal karyotype, respectively. The common deletion region of 7q- was 7q21a222 (ten cases) and 7q31-35(ten cases). FISH assay confirmed the -7/7q- aberration in those with clonal -7/7q- abnormalities, but failed in those with random -7/7q- and normal karyotype. In 7q- group, FISH revealed seven of eleven cases with monosomy 7 clone detected in the same specimen, but the numbers of 7q- interphases cells were much greater than those of monosomy 7 cells (average 42.5% vs 8.4%, P=0.025). FISH also provided precise refinement for three chromosomal structural abnormalities associated with 7q seen in CAA, one case with del(7)(q22) being refined as chromosomal translocation, one case with 7q+ being confirmed as dup(7q), and one case with complex translocation involving 7q being also proved to be true.</p><p><b>CONCLUSION</b>FISH is a powerful tool to identify or refine chromosomal structural aberrations involving 7q, and it provides accurate evaluation of -7/7q- in all the patients. -7 and 7q- clone frequently coexist in the same specimen, and the significantly increasing percentage of 7q- cells implies that -7 clone secondary to 7q- clone is a result from loss of 7q-.</p>