The Retinoblastoma Genetic Screening Unit tests blood and tumour samples for mutations in the Retinoblastoma gene (RB1).  RB1 mutations predispose for the development of retinoblastoma, a childhood eye cancer which can be inherited.  Tumours form due to two RB1 mutations, either of which may be heritable. Knowing whether the retinoblastoma is heritable helps to inform clinical care, family planning, and risk assessment in family members. Here we present the spectrum of genetic and epigenetic changes identified in 403 retinoblastoma patients. 111 of the identified mutations were novel. We achieved a high mutation detection rate using a variety of molecular screening techniques, allowing the exclusion of siblings/children of patients from undergoing expensive and unnecessary examinations under anaesthetic if they are not mutation carriers. (By Dr. Zerrin Onadim, http://jmg.bmj.com/content/early/2013/11/13/jmedgenet-2013-101821 )