Increased risk of lymphoproliferative disorders in relatives of patients with B-cell chronic lymphocytic leukemia: relevance of the degree of familial linkage.

We assessed the familial aggregation of chronic lymphoproliferative diseases (CLD) in 3962 relatives of 169 patients with B-cell chronic lymphocytic leukemia (B-CLL). Data collection included a self-administered questionnaire. The "relative risk" considered the connection between a higher incidence of CLD and the degree of familial linkage with the probands. The model of logistic regression was statistically significant (p < 0.001), with the probability of CLD increasing in proportion to the relationship coefficient between parents, siblings and children [(relationship coefficient 0.5; probability of CLD 1.85 (C.I. 95%, range 1.1-3%)]. CLD, particularly B-CLL, were observed in first-degree relatives of the patients with B-CLL more often than in other relatives.