Some families carry genetic changes that greatly increase their risk of developing blood cancers such as leukaemia. Using the latest DNA sequencing technologies, we have identified causal mutations in a gene called DDX41. How this gene causes blood cancer is unknown. In this proposal, we will examine functions of DDX41 in blood cells to determine how it works normally and how it causes leukaemia. We will also identify new targets for treating blood cancers with mutations in DDX41.