Familial polycythemia.

Since erythropoiesis is regulated at a number of steps, it seems likely that multiple genetically determined defects could result in polycythemia in families. These defects might be recognized by distinct patterns of marrow regulation--physiologic studies relating ESF production, oxygen transport, and red cell production in affected individuals. Defects in renal or extrarenal mechanisms of ESF production and release, oxygen sensing by the kidney, and in receptor site number or function on target cells within the marrow should be characterized by distinctive patterns of ESF production at rest and in response to altered oxygen supply. Continued study should allow the dissection of levels of regulation under genetic control and lead to a better understanding of the physiology of red cell production in normal man.