Anticipation in familial plasma cell dyscrasias.

Familial myeloma was described as early as 1925; however, the causative factors are unknown. Studies of families with other familial haematological malignancies demonstrate anticipation. Five new families are described in which plasma cell dyscrasias occurred in parent and child generations (six such pairs), and data were pooled with those of 16 other families (with 20 parent-child pairs affected) recorded in the literature. Disease-free survival for parent and child generations were each estimated and differences in the disease-free survival between generations were tested by the log-rank and signed rank methods. In all six previously unreported parent-child pairs with plasma cell dyscrasia and in 18/20 such pairs found in the literature, the disease occurred at an earlier age in the child generation. The median age of onset of myeloma in the parent and child generations of all 26 pairs was 71 years (95% CI 67-78 years) and 50 years (95% CI 45-55 years), respectively (P<0.0001). The ages of onset of malignant plasma cell dyscrasias in the parent and child generations of these families compared with patients in the general population were significantly different for the child generation (P<0.005) but not for the parent generation. It would appear that anticipation occurs in familial myeloma.