We aim to understand the molecular basis of chromosome stability in human cells. Genetic predisposition to cancer is commonly precipitated by mutations in genes that result in chromosome breakage. Studies of the inherited chromosomal instability diseases in humans have led to the discovery of some of these genes, and the characterization of their products may profoundly contribute to our understanding of pathways that maintain genetic integrity. By utilising a variety of complementary approaches, we are probing the function of these essential proteins.