Familial erythrocytosis with over-production of erythropoietin.

A family is described in which the father and son had erythrocytosis associated with a normal Hb oxygen affinity. Growth of erythroid colonies in vitro (BFU-E) exhibited normal erythropoietin dependence. In the son there was an enlarged erythroid precursor compartment, while the father (who had been treated by busulphan) showed marked reduction of circulating BFU-Es. Serum erythropoietin (Epo), estimated by radio-immunoassay, was 96 miu/ml in the son and 360 miu/ml in the father (normal 25, SD 6, n = 46). We conclude that erythrocytosis in this family is due to a genetically determined hyper-production of Epo. The finding in the father of a high Hb level associated with increased Epo and decreased BFU-Es might support the hypothesis that red cell mass is regulated by Epo at the level of bone marrow CFU-Es rather than BFU-Es.