[Two cases of familial occurrence of aplastic anemia].

It is quite rare that aplastic anemia except Fanconi's type occurs in members of a single family. Here we reported two patients with aplastic anemia, a 14-year-old female and a 49-year-old her mother. In both cases, hematological findings were compatible to that of a typical aplastic anemia. In the case of daughter, CFU-E formation of control bone marrow cells was significantly inhibited by the addition of the patient's bone marrow cells, suggesting the presence of cellular immune mechanism. In the case of mother, no inhibitory activity on CFU-C formation of control bone marrow cells was detected in the patient's serum, though the ratio of helper/suppressor T lymphocytes in the peripheral blood was increased. We could not sufficiently clarify the common immune mechanism causing aplastic anemia in both cases. It was noticeable, however, that both cases share HLA DR2, which is frequently found in patients with various autoimmune diseases and is believed to relate closely to the pathogenesis of autoimmune diseases. This evidence suggests the possibility that genetically inherited susceptibility may also be the important factor for causing aplastic anemia.