Based on the evidence that a germline ABRAXAS mutation is associated with an increased risk of breast cancer in the Finnish population and owing to the crucial role of this protein in DSB repair, we sought to estimate the frequencies and nature of rare ABRAXAS variants in a sample of women with early onset breast cancer (N = 1,332) and frequency matched controls (N = 1,123) from three population-based centers of the Breast Cancer Family Registry (BCFR) [29] by screening ABRAXAS exons and exon/intron boundaries. Here, ABRAXAS1 is linked to breast cancer.