Different studies have found the presence of variants in BRCA1 and BRCA2: in a total of 450 patients with early onset colorectal cancer, four variants were identified in BRCA1 and one variant in BRCA2 [44]; in 1260 individuals with a family history of LS, 8% had variants in these genes [45]; and in a cohort of 961 endometrial cancer patients, 1.04% presented with a PV [46]. Here, BRCA1 is linked to acquired polycythemia vera.