In a study of pedigrees with a family history of CLL, four POT1 germline mutations (p.Tyr36Cys, p.Gln376Arg, p.Gln358SerfsTer13 and c.1164-1G > A) were found to co-segregate with CLL occurrence (6%, n = 4/66). This evidence concerns the gene POT1 and B-cell chronic lymphocytic leukemia.