[Familial occurrence of chronic lymphocytic leukemia: report of three siblings (author's transl)].

Chronic lymphocytic leukemia was diagnosed in three siblings. Familiar occurrence speaks in favor of a predisposition in this disorder of unknown etiology. According to the present status of knowledge endogenous - genetically determined - factors combined with exogenous factors (viruses, radiation exposure, toxic substances) participate in the etiopathogenesis of the different forms of leukemia.