Among the 51 biallelic MCM8 variant carriers in the 100000 Genomes Project, 2 individuals (3.9%) had CRC, 3 (5.9%) had colonic polyps, 3 (5.9%) had colonic adenomas, 3 (5.9%) had rectal polyps, 2 (3.9%) had hypothyroidism, and 5 (9.8%) had breast cancer. The gene discussed is MCM8; the disease is breast cancer.