People born with a mutation in a gene called PTEN often develop cancer, but also show other symptoms including benign growths, an enlarged head and autism. To date it has been unclear whether the diversity seen in these patients is caused by differences in the way precise genetic changes alter the function of PTEN, or by other factors. By studying how different PTEN proteins function in cells in the laboratory, our work found that mutations with specific effects on the function of the PTEN protein were more commonly found in particular patient groups. The clinical prospects of these patient groups are very different. Therefore, information at initial diagnosis would be of great benefit if it could predict from the specific mutant PTEN protein inherited, what problems the patient is likely to develop. In the future this may be able to match patients with the best treatments. (By Dr Nicholas R Leslie, http://jmg.bmj.com/content/early/2014/12/19/jmedgenet-2014-102803 )