Genetics Overview

What are copy number variants and how do they help scientists?

Copy Number Variant or CNVs are a complex form of genetic variation where DNA is present in greater or less amounts in an individual compared with the average population. CNVs are caused by a deletion or duplication of DNA segments and are the largest single source of variation among individuals. As with other genetic differences, not all CNVs result in health or behavior issues.

CNVs are primarily inherited, but can also occur for the first time when a baby is conceived or during cell division sometime later in life. CNVs are studied using high-resolution genome analysis techniques. The main method is called Comparative Genome Hybridization or CGH. With this technique, researchers put DNA segments of interest on a “chip.” Next, fluorescently labeled DNA from the research subject is used to “probe” the chip. CNVs are detected by comparing how bright the subject’s signal is from the control DNA. If there is a deletion in the subject’s sample, the signal is not as bright. If there is a duplication, the signal is brighter.