Given technology-driven FISH, aCGH approaches have yet to reach the much-touted promise of universal coverage or cost efficacy to sample investigated, deep chromosome analysis and molecular cytogenetics will remain relevant for technology translation, study design and therapeutic assessment for many years.

This book provides a classification system to clarify the disease implications of cytogenetically visible copy number variants using cytogenetic assessment of heterochromatic or euchromatic DNA variants. While variants of several megabasepair can be present in the human genome without clinical consequence, how to visually circumvent these benign areas and provide laser-focused assessment of disease implications is not always appreciated by practitioners used only to highly costly molecular profiling methods (FISH/aCGH/NGS). Knowledge of the rare but recurrent rearrangements unfamiliar to practitioners saves time and money for molecular cytogeneticists and genetics counselors in helping to distinguish benign from harmful CG-CNV. It also supports them in further assessment of which molecular cytogenetics tools to deploy.