Cytogenetic methods

This chapter outlines the methods currently employed in cancer cytogenetics, spanning from chromosome banding to array- and sequencing-based techniques. A correct sampling procedure is the basis for correct scientific and diagnostic conclusions. Chromosome preparation requires live cells, whereas in situ hybridization at least requires intact nuclei, and genome arrays as well as sequencing rely on DNA that has not been extensively degraded. Direct preparations or short-term cultures are therefore usually preferred for chromosome banding analysis. In situ hybridization techniques are based on the inherent organization of DNA into two antiparallel complementary strands. Genomic arrays are highly efficient tools for obtaining data on genomic imbalances present in a tumor sample. The advent of massive parallel/second-generation/ next-generation sequencing (NGS technology has radically transformed the field of cancer cytogenetics. More than 800 genomes of more than 25 cancer types have now been sequenced.