Breast cancer is the most common cancer in women yet for most women the genetic changes underlying their disease remain undetermined or poorly understood. My multi-disciplinary proposal aims to address this clinically important issue by exploiting strong local clinical linkages and international collaborations to implement advanced breast cancer genomics research within New Zealand. Specifically, my study aims to determine the clinical and biological impact of 1) DNA sequence variants in known breast cancer susceptibility genes, and 2) DNA copy number variants across the genome, in breast cancer development. Through a series of successful applications to large international consortia I have secured access to resources critical for the success of this study. I am thus well positioned to lead this ambitious proposal and make significant contributions to an exciting and important research area that is developing at a rapid pace, with the ultimate goal of translating new discoveries into clinical care.