Clinical and hematologic features of 300 patients affected by hereditary spherocytosis grouped according to the type of the membrane protein defect

Background: Hereditary spherocytosis is a very heterogeneous form of hemolytic anemia. The aim of this study was to relate the type of molecular defect with clinical and hematologic features and response to splenectomy using information from a large database of patients. Design and Methods: Data from 300 consecutive patients with hereditary spherocytosis, grouped according to the results of sodium dodecyl sulphate-polyacrylamide gel electrophoresis, were analyzed and the sensitivity of red cell osmotic fragility tests was compared in various subsets of patients. Results: Band 3 and spectrin deficiencies were the most common protein abnormalities (54% and 31%, respectively); 11% of cases were not classified by the electrophoretic analysis. Spectrin deficiency was more frequently diagnosed in childhood and band 3 deficiency in adulthood. Hemoglobin concentration was slightly lower, spherocyte number and hemolysis markers higher in spectrin deficiency than in band 3 deficiency. The sensitivity of the osmotic fragility tests ranged from 48% to 95%, and was independent of the type and amount of the membrane defect. The association of the acidified glycerol lysis test and the NaCl test on incubated blood reached a sensitivity of 99%. Splenectomy corrected the anemia in patients with all subtypes of hereditary spherocytosis although spectrin-deficient patients still showed increased reticulocyte numbers and levels of unconjugated bilirubin. Splenectomy allowed the identification of the membrane defect in all the previously unclassified patients, most of whom had spectrin and/or ankyrin deficiency. Conclusions: The definition of the red cell membrane defect in hereditary spherocytosis has no major clinical implications, but may be useful for a differential diagnosis from other hematologic disorders that mimic this hemolytic anemia.