The PMS1 variant (p.Lys455Glu, SCV005329257) was found in a woman who had colon and rectal cancer aged 70 (MSI-H) and had 4 other affected family members: 3 deceased women with breast cancer (35–50 years old) while her surviving brother had prostate cancer (72 years). Here, PMS1 is linked to breast carcinoma.