ATM and prostate cancer: CHEK2 is a checkpoint kinase gene, activated by ATM and regulating BRCA1. The most common pathogenic CHEK2 mutation, c.1100delC, has been associated with an increased risk of lethal versus indolent prostate cancers (respectively, 1.28% vs. 0.16% P = 0.004), giving a poor prognosis to this mutation [28].