CHEK2 and breast cancer: In our experience, a recurrent germline mutation in CHEK2 (c.444+1G>A, c.1100delC, del5395) and PALB2 (c.509_510delGA and c.172_175delTTGT) can be found, respectively, in 1.98% and 1.98% of Polish patients with breast cancer using multiplex PCR, allele-specific PCR, (ASA-PCR), Restriction Fragment Length Polymomorphism (RFLP) and PCR-HRM (PCR-High Resolution Melting) (preliminary data).