MRC1 and endometrial cancer: One patient harbored 2 heterozygous variants in EGFR and MSH2. In addition to canonical Lynch syndrome–associated MMR genes (17 [40.5%]), P/LP variants in HRR genes, which are not canonically associated with endometrial cancer, also represented 47.6% of germline findings in endometrial cancer (n = 20) (Figure 1B; eTable 3 in Supplement 1).