Following their significant association with primary ovarian insufficiency (POI; HP:0008209),2,3,4,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40 biallelic germline variants of MCM8/MCM9 were first linked to cancer in several families with polyposis (HP:0200063) and early-onset colorectal cancer (CRC; HP:0003003).2 Here, MCM9 is linked to Onset.