Abstract
Over the past several decades, clinical cytogenetics has branched out from the use of light microscopy and examination of banded chromosomes to embrace multiple newer techniques, including fluorescence in situ hybridization (FISH), multiple generations of microarray designs, as well as the newest technologies, namely, optical genome mapping (OGM) and genomic proximity mapping (GPM). While these newer technologies have had an increasingly molecular genetic focus over time, they are still rooted in the field of cytogenetics, the genetics of the single cell. This review provides a brief overview of the earliest, as well as the most recent, techniques available to clinical cytogenetics laboratories for both constitutional and neoplastic testing and discusses some advantages and disadvantages of each.