CHEK2 and cancer: The CHEK2 R95* mutation was observed in four out of 3748 individuals without any cancer diagnosis (0.11 %; Minor allele frequency [MAF] 5.3 × 10−4; Table 1), in four out of 1717 breast cancer patients (0.23 %), and in four out of 2501 prostate cancer patients (0.16 %).