"Background: Hereditary cancer is an important cause of morbidity and mortality and over the last 20 years, the majority of highly penetrant risk alleles such as BRCA1, BRCA2 in breast cancer and APC, MLH1, MSH2 in colon cancer have been identified. However, there are many men and women who have a strong family of cancer for whom we cannot provide answers because no mutation is found in known genes.Objectives: i) To identify new candidate breast cancer susceptibility loci by an innovative combination of exome sequencing technology and genome-wide allele-specific expression analysis of BRCA1/2-negative women with strong family histories of BC. This approach will be complemented by exomic sequencing of carefully selected matched cohorts of women with unilateral and bilateral breast cancer on whom extensive demographic and clinical data is available. ii) To study selected gene candidates in more detail at the DNA, RNA and protein level. iii) To apply the knowledge gained in the genomic study of breast cancer to other cancer predisposition syndromes.Significance: At present, the new combined approach of EST and ASE has several advantages over the alternative option of whole genome sequencing in the identification of rare functional variants; not only will EST plus ASE be cheaper and faster than a whole genome sequencing approach, but it will also allow us to explore the potentially unappreciated roles of allelic silencing (through regulatory or epigenetic variants) in cancer susceptibility, which would not be captured using genomic sequencing in isolation. We will commence the project with breast cancer families and then apply the same approach to other types of hereditary cancers. This proposal is focused on individuals who face a truly high risk for cancer but for whom predictive information is lacking and therefore this proposal is likely to have a direct translational benefit."