This important review of John Barber highlights and summarizes the known euchromatic copy number variants which are large enough to be visualized already under the microscope. No array-CGH studies were necessary for their identification. So, this is an important paper showing that the finding of a chromosomal aberration not always means that the reason for clinical abnormality of a patient has been identified - see e.g. also doi: 10.3892/mmr_00000299. Major parts of this work were also used in the book: "Benign & Pathological Chromosomal Imbalances, 1st Edition Microscopic and Submicroscopic Copy Number Variations (CNVs) in Genetics and Counseling. Academic Press. ISBN : 9780124046313"