The two major genes BRCA1 (BReast CAncer gene 1) and BRCA2 (BReast CAncer gene 2), together with rare high penetrance genes (TP53 (Tumor protein 53), PTEN (Phosphatase and tensin homolog), CDH1 (Cadherin-1) and STK11 (Serine/threonine kinase 11)) and moderate penetrance genes collectively explain ~30% of familial BC risk [2]. Here, STK11 is linked to breast cancer.