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A systematic screen of engineered mouse lines found that mutations in previously unstudied genes were just as likely to produce effects as those in genes that had already been explored in other scientific publications.

Karen Steel at the Wellcome Trust Sanger Institute in Cambridge, UK, and her colleagues analysed 489 genes by systematically disabling each one in a separate mouse line. More than 40% of these genes were found to be essential for survival.

Adult mice from 250 of the lines were run through a wide range of tests, revealing traits such as reduced grip strength, fused joints, delayed response to heat, impaired hearing and altered blood chemistry.

Many results were unexpected: for example, disabling a gene that is thought to be involved in hearing led instead to increased body weight. Both the data and mutants are publicly available, and multiple groups are working together to perform similar tests on thousands more genes.

Cell 154, 452–464 (2013)