AFF3 and breast cancer: AFF3 has been identified as a novel susceptibility locus for several autoimmune diseases, notably rheumatoid arthritis,30, 31, 32, 33 type I diabetes34, 35 and Graves' disease.36AFF3 has been found to be abnormally expressed in ~20% of breast cancers, suggesting that it may act as a proto-oncogene.37 A gene set enrichment analysis of several expression data sets from breast cancers shows a link between genes correlated to AFF3 expression and the Wnt/β-catenin pathway (Supplementary Figure S6-A).