Pyridoxine responsive hereditary sideroblastic erythropoiesis and iron overload: two microcytic subpopulations in the affected male, one normocytic and one microcytic subpopulation in the obligate female carrier.

Mild hepatic iron overload has been demonstrated by magnetic susceptibility measurements in a 22-year-old man with hereditary sideroblastic erythropoiesis despite hemoglobin levels in the normal range and a normal erythropoietin level. His grandfather's sideroblastic anemia has been found to be responsive to pyridoxine; his mother's hemoglobin has persisted in the normal range but red cell volume distribution analysis demonstrated two subpopulations; 30% with estimated geometric mean of 68 fl and 70% an estimated mean of 93 fl. Red cell distribution analysis of the grandson demonstrated two microcytic subpopulations; 46% with an estimated geometric mean of 45 fl and 54% an estimated mean of 70 fl. A therapeutic regimen is outlined to reduce to normal his iron stores and to prevent the future development of excessive iron overload. © 1993 Wiley-Liss, Inc.