Our results showing high prevalence of the CDKN1Brs36228499A or CDKN1Brs2066827G alleles promoting p27Kip1 increase and cell accumulation in CLL patients are in line with those obtained for the protective action of both genetic variants in organ transplantation and tumors [49,63,64,65,66,67,68,69]. The gene discussed is CDKN1B; the disease is B-cell chronic lymphocytic leukemia.