there was little or no evidence of heterogeneity in the OR estimates between studies, indicating that the associations apply broadly to populations of European ancestry. With more than 60 established breast cancer susceptibility loci, it is becoming possible to discern some more general patterns among the loci. Although most of the underlying genes and variants remain to be identified, there is a clear excess of genes either known to be involved in tumorigenesis in model systems or involved in processes relevant to cancer, such as cell death and differentiation. However, for other loci, such as PEX14, there is no obvious link to cancer susceptibility. Nine of the new loci lie in chromosomal regions with no known genes, suggesting that these may provide further examples of long-range regulation similar to that seen in the 8q24 region59. We have identified three additional examples of loci in the vicinity of susceptibility loci for other cancers (TET2, 8q24 and DNAJC1). These associations might reflect the tissue-specific regulation of key genes, and understanding the functional mechanisms underlying these associations may be particularly informative.
