Cytogenetic Studies

Abstract

Cytogenetics refers to studying chromosomes in individual cells and their relationship to human disease. Abnormal cytogenetic findings can be found in the number and structure of the chromosomes, such as amplification, deletions, translocations, inversions, duplications, or isochromosomes. Conventional cytogenetic studies allow complete karyotype analysis using chromosome-banding techniques and detect most chromosome anomalies; however, it is a cumbersome and time-consuming procedure requiring adequate fresh tissue and special cell culture techniques in order to obtain an adequate number of proliferating cells. FISH, using fluorescently labeled probes, is currently more often used than conventional cytogenetic analysis because it is a relatively easy and fast technique to detect well-documented specific chromosomal abnormalities and allows the localization of specific genes and DNA segments on specific chromosomes and may detect some abnormalities (e.g., microdeletions or duplications) that cannot be identified by conventional banding methods. FISH is particularly advantageous for FNA specimens because it can be tested on nondividing cells (so-called “interphase FISH”) and only requires small number of cells. The drawback of FISH technique is that it requires knowledge of the specific loci involved in an aberration and is not informative to identify “unexpected” chromosome abnormalities.