Genetic factors predisposing to chronic lymphocytic leukemia and to autoimmune disease.

Among 320 relatives of 28 patients with chronic lymphocytic leukemia (CLL), 4 had CLL, 1 had lymphosarcoma, and 2 other adults had leukemia of unknown type. Autoimmune disease including hyperthyroidism, pernicious anemia, rheumatoid arthritis and systemic lupus erythematosus affected 18 relatives. HLA typing of members of two families demonstrated that within each family the patient with CLL shared a common haplotype with relatives with autoimmune disease, but the haplotype was different in the two kindreds. In contrast, CLL was encountered in only 1 and autoimmune disease in 4 of 396 relatives of a group of 28 control patients. These data together with information from earlier reports support the hypothesis that genetic factors distrubing the regulation of the immune system may predispose both to lymphoid neoplasms and to autoimmune disease. The concept is supported by an array of experimental studies in animals.