PIK3R1 and breast cancer: Among the Bonferroni significant hits, 9 out of the 344 (2.62%) genes prioritised for the breast cancer GWAS are known somatic tissue-specific cancer drivers (FGFR2, MAP3K1, RAD51B, ESR1, CDKN2A, CASP8, TBX3, AKT1 and PIK3R1, Fisher exact p-value: 0.00041, median distance to nearest index variant = 34.9 Kb).