Families with non-Hodgkin lymphoma and plasma cell dyscrasias in their pedigrees.

Although reports of familial clustering of hematologic malignancies have appeared for decades, the cause(s) of this uncommon occurrence is still not completely understood. Most modern investigations, however, support a genetic rather than an environmental exposure as a cause of this observation. Most pedigrees of families with familial hematologic malignancies demonstrate age of onset anticipation, with the disease diagnosed at an earlier age in successive generations. The cause of this phenomenon is clear in some familial neurologic disorders (trinucleotide repeat expansion) but not at all clear in familial hematologic malignancies. In preparation for molecular studies of familial clustering of hematologic malignancies, we have collected pedigrees on 738 families and have previously demonstrated anticipation in those with familial plasma cell myeloma, chronic lymphocytic leukemia, Hodgkin lymphoma or non-Hodgkin lymphoma (NHL). Here we present data on 36 families with both plasma cell myeloma and NHL in their pedigrees and demonstrate strong evidence for anticipation in these families. We encourage all health care personnel to ask patients multiple times about family medical history and carefully take note of family histories from individuals with uncommon illnesses and to refer families with clustering of such illnesses for further investigation.