CHEK2 and acquired polycythemia vera: Some of the germline mutations in the DNA damage response gene CHEK2 observed in an analysis of 235 DLBCL patients16 are identical to those that were shown to confer an increased risk for solid tumors,24 and possibly essential thrombocythemia25 and polycythemia vera.26 Mechanistically, the CHEK2 c.444+1G>A mutation leads to a truncated protein lacking the kinase activation domain and part of the functionally relevant forkhead homology-associated domain.