Familial multiple myeloma: report of fifteen families.

To further define the frequency, clinical and biological features of familial multiple myeloma we performed a retrospective study of related patients who presented with multiple myeloma. Most cases of familial multiple myeloma were observed in siblings (10/15), in whom the mean age at diagnosis was similar to unrelated multiple myeloma. In successive generations the mean age at diagnosis was lower. Monoclonal component was identical (IgG kappa) in seven families. Familial history of monoclonal gammopathy of undetermined significance was observed in three families. Five other prospective studies of 1263 patients identified four affected families (3.2 per 1000 cases of multiple myeloma), and raise the question of a genetic background in multiple myeloma.