ESR1 and breast cancer: Although not all samples were available for genotyping, family history shows two first cousins on the proband's maternal side, one diagnosed with HGSC at age 48 (PID: II‐20) and another diagnosed with HGSC (clinical stage IIIC) at age 67 (PID: II‐22) and is a heterozygote, transmitting RAD51C c.571 + 4A > G to her daughter (PID: III‐33) who was diagnosed with BC (invasive ductal carcinoma, clinical stage III, ER, PR, and HER2 negative) at age 37 and HGSC (clinical stage IIIB) at age 41.