knockout mouse

A knockout mouse is a laboratory mouse in which one or more genes have been turned off or "knocked out." To create a knockout mouse, scientists genetically engineer the animal by disrupting a gene of interest. This may be done by deleting portions of the gene's DNA sequence to make it nonfunctional or by replacing the gene with an altered sequence. Knockout mice are used to study what happens in an organism when a particular gene is absent. Studying knockout mice can provide information about how the knocked-out gene normally functions, including the gene's biochemical, developmental, physical, and behavioral roles. Because humans and mice share many genes, knockout mice are often used to discover the functions of human genes and to study human diseases.