Genetic heterogeneity and familial carcinoma of the breast.

The particular patterns of familial aggregations of cancer in the several families reported from our clinical resource suggest that multiple genotypes explain their diversity of cancer susceptibility. This knowledge could be of value in improving cancer control. We postulate that each particular genotype functions in concert with differential carcinogenic interactions, including a possible oncogenic virus, contributing to carcinogenesis in the susceptible patient. This reasoning is consistent with a concept of genetic heterogeneity as an explanation for familial carcinoma of the breast. This phenomenon is not unlike the current explanation for the genetics of the mucopolysaccaridoses, the lipidoses and several other major disorders of man which show genetic heterogeneity.