ABSTRACT
The discovery of the genetic changes that contribute to cellular neoplastic transformation is one of the major aims in oncological research. Chromosome rearrangements account for a large part of these initiating mutations that, resulting in gene deregulation, are the main target of molecular cytogenetics. Cytogenetics, based in reasoned genomic and biological questions and supported by the development of new biotechnological tools, is a powerful discipline that is continuously generating pieces of information that have immediate translation as reagents for diagnosis and useful research data. The present review presents a summary of the major cytogenetic findings that already have a clear role in clinical oncology because of their use as diagnostic markers, as indicators of molecular therapy suitability or both. We also present an updated description of the molecular cytogenetics tools that have included genomic advances in their most recent releases: multicolour fluorescence in situ hybridisation methods (e.g. SKY karyotyping) and array-based comparative genomic hybridisation (arrayCGH).