An efficient method of fluorescence in situ hybridization: Application on archival G-banded slides

摘要

In situ hybridization (ISH) has proven to be a very important adjunct to classic cytogenetic techniques for detecting DNA sequences in both metaphase and interphase cells, and for evaluating numerical and structural chromosomal aberrations. Several combination methods of G-banding by the trypsin technique with Glemsa staining and fluorescence in situ hybridization (FISH) have been developed for chromosome identification in the past few years. However, these methods are impractical to use in the clinical laboratory because results are often inconsistent and the procedure is labor-intensive. To develop a more clinically useful method, we compared the manufacturer's standard FISH protocol with two alternative protocols. Fresh G-banded slides from a pool of ten karyotypically normal peripheral blood samples and archival G-banded slides from two patients with malignant hematological disorders were hybridized with whole chromosome-specific DNA painting probes (COATASOME~K, Oncor Inc.). One alternate protocol in which G-banded chromosomes were codenatured simultaneously with the indirect-labeled COATASOME DNA probe gave good preservation of chromosome morphology and consistently reliable intense FISH signals. This procedure significantly reduced the turnaround time and was less labor-intensive; it was also used to define multiple chromosomal translocations In two patients with malignant hematological disorders. The findings demonstrate a relatively simple, efficient, and reliable method of sequential G-banding and FISH for use In clinical cytogenetics.