In another study, the prevalence of CHEK2 germline pathogenic variants (c.172_175delTTGTT; c.509_510delGA) in BRCA1/2-negative Polish patients with breast and ovarian cancer was 1.5% [38], and in another study, the prevalence of the c.509_510delGA mutation in PALB2 in Polish breast and ovarian cancer patients was 0.6% (n = 4/648) [39]. Here, BRCA1 is linked to ovarian cancer.