Abstract
The first two families to be identified in the United Kingdom with the Li-Fraumeni syndrome of familial cancer are reported. The first family comprises breast carcinoma in the mother and adrenocortical carcinoma, medulloblastoma, and rhabdomyosarcoma in three of her four children, and the second family comprises breast carcinoma in the mother and adrenocortical carcinoma and rhabdomyosacrcoma in two of her three children. All three of the surviving children with malignancy, and one other who has recently died, possess the tissue type antigen B12.