MSH6 and acquired polycythemia vera: Importantly, remaining 17 PV carriers, who would not be indicated for genetic testing using current indication criteria, still represent a significant proportion (28.3%) of cases carrying a germline PV in the LS (MLH1, MSH6) or the HBOC (ATM, BRCA1, BRCA2, BRIP1, CHEK2) genes.