Familial leukemias.

Familial leukemia has been described for more than 50 years but only recently have modern genetic techniques allowed for the investigation of the genome. Genome-wide association studies have identified a number of genetic sites that appear to relate to susceptibility to leukemia in certain families and occasionally to susceptibility to a specific leukemia in general. Many questions remain, including susceptibility to what? An oncogenic virus? An environmental chemical? Mutation of another gene induced by a heritable mutation-promoting gene?.Clinically important facts have been learned. Chronic lymphocytic leukemia (CLL) is by far the most common familial leukemia. Patients with CLL have approximately a 10% chance of a first-degree relative developing CLL, and even a greater chance of one developing monoclonal B-cell lymphocytosis which may be an asymptomatic forme fruste of the neoplasm. Furthermore, there may be an increased incidence of breast cancer in familial CLL pedigrees which raises the question of a common etiology for neoplasms in general, or at least a previously unrecognized relationship among them.