A 4 year old male child with congenital hemolytic anemia and bizarre red cell morphology has been studied. Many cells showed blunt projections plus fragmentation and there were numerous microspherocytes. Splenomegaly was present and splenectomy at the age of 21 months resulted in an increase in hemoglobin from 4 to 10 gm% and a fall in reticulocytes from 23 to 3%. However, the abnormal red cell morphology persisted. Microcytosis remained extreme with MCV 42 μ3 and the MCHC was 38-44 gm%. Osmotic fragility was greatly increased. Tests for usual red cell abnormalities and unstable hemoglobin were negative while the intracellular concentrations of Na+ and K+ were normal. Moreover both active and passive components of Na+ and K+ fluxes were normal. Inward Ca2+ movement was measured in cells in which the activity of the outwardly-directed Ca2+ pump was inhibited. When cells were incubated in 1.5 mM Ca2+, the entry of Ca2+ was increased more than 10-fold, from 64.0' nanomole/ml cells/4 hr. for the patient compared with Ca2+ 5.3± 1.6 nanomole/ml cells/4 hr. for normals. Measurement of activity in the patient's red cells was normal. The results suggest that a selective inward Ca2+ leak may be responsible for the red cell fragmentation and microcytosis in this syndrome.
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