Replication of breast cancer GWAS susceptibility loci in the women's health initiative African American SHARe study

Background: Genome-wide association studies (GWAS) have identified loci associated with risk of breast cancer. These studies have primarily been conducted in populations of European descent. To fully understand the impact of these loci, it is important to study groups with other genetic ancestries, including African American women. Methods: We examined 22 single-nucleotide polymorphisms (SNP), previously identified in GWAS of breast cancer risk in European and Asian descent women (index SNPs), and SNPs in the surrounding regions in a study of 7,800 African American women (including 316 women with incident invasive breast cancer) from the Women's Health Initiative SNP Health Association Resource. Results: Two index SNPs were associated with breast cancer: rs3803662 at 16q12.2/TOX3 (Hazard ratio [HR] for the T allele = 0.79, 95% CI: 0.67-0.92, P = 0.003) and rs10941679 at 5p12 (HR for the G allele = 1.31, 95% CI: 1.06-1.63, P = 0.014). When we expanded to regions, the 3p24.1 region showed an association with breast cancer risk (permutation based P = 0.027) and three regions (10p15.1, 10q26.13/FGFR2, and 16q12.2/ TOX3) showed a trend toward association. Conclusion: Our findings provide evidence that some breast cancer GWAS regions may be associated with breast cancer in African American women. Larger, more comprehensive studies are needed to fully assess generalizability of published GWAS findings and to identify potential novel associations in African American populations. Impact: Both replication and lack of replication of published GWAS findings in other ancestral groups provides important information of the genetic etiology of this disease and may impact translation of GWAS findings to clinical and public health settings.