Familial chronic lymphocytic leukemia in Norway and Denmark. Comments on pleiotropy and birth order.

Aim: To investigate the genetics of chronic lymphocytic leukemia (CLL).

Materials And Methods: In 56 (7%) out of 800 CLL patients with concomitant malignant hematological disease, 51 families and 141 cases were ascertained.

Result: 106 cases (75%) of CLL, 27 cases (19%) of nonCLL and 8 cases (6%) of myeloproliferative disorders. Paternal disease was transmitted primarily to the youngest sons in the sibship while maternal disease was transmitted equally to all sibs, demonstrated by means of matrix conjugation and confirmed with Cox regression on parity and birth order (maternal-offspring combination: relative risk (RR), 95% confidence interval (CI)=1.47 (0.89 - 2.43), p=0.12, compared with paternal-offspring combination: RR=3.25, 95% CI=(1.57-6.72), p<0.001). The B-cell expression in familial and sporadic CLL was indistinguishable.

Conclusion: Parental genomic imprinting is pointed out as one possible mechanism behind this non-Mendelian genomic output.