Erythrocyte Membrane Protein Alterations by SDS-PAGE and Underlying Clinical Heterogeneity in Hereditary Spherocytosis

Yoo, Eun Sun; Choi, Hyoung Soo; Shin, Hee Young; Ahn, Hyo Seop; Lee, Young Kyung; Cho, Han Ik

Abstract

BACKGROUND: Hereditary spherocytosis(HS) is a clinically and biochemically very heterogeneous disorder The purpose of this study is to detect erythrocyte membrane protein abnormalities by SDS-PAGE and to investigate the frequency of erythrocyte membrane protein defects in hereditary spherocytosis and correlation between some of the hereditary spherocytosis biochemical subsets and the selected clinical phenotype.
METHODS
We evaluated the clinical and laboratory characteristics of 14 normal healthy persons and 23 hereditary spherocytosis patients and 8 their family members. The patients were divided into three groups based on clinical and hematological severity(mild, typical, severe). In addition to routine hematologic determlnatlons, osmotic fragility and autohemolysis, RBC membrane protein analysis were performed in all patients by densitometric tracing of SDS-PAGE(sodium dodecyl sulphate polyacrylamide gel electrophoresis) stained by Coomassle blue utilizing both the discontinuous buffer system of Laemmli with acrylamide linear gradient from 4% to 12% and the continuous buffer system of Fairbank with exponential gradient of acrylamide from 3.5% to 17%.
RESULTS
1) The patients could be seperated into three classes of different clinical severity as mild(3 cases), moderate(16 cases) and severe(4 cases) on the clinical feature. 2) Eighteen patients(82.6%) among 23 hereditary spherocytosis revealed abnormal erythrocyte membrane protein and we detected six patients(26.1%) with spectrin deficiency combined with ankyrin reduction, 4 patients(17.4%) with ankyrin deficiency, 4 patients(17.4%) with isolated spectrin deficiency and 3 patients(13.0%) with band 3 deficiency. Five HS patients(21.7%) showed normal RBC membrane protein. 3) Eight HS and their family members showed same RBC membrane protein deficiency. 4) The type and degree of RBC membrane protein reduction were variale with spectrin at 66~94%, with ankyrin at 48~82% of normal levels. These showed that each patient had different clinical severities according to different RBC membrane protein levels and type.
CONCLUSION
RBC membrane protein abnormalities were observed in 82.6% of HS patients. The combined spectrin and ankyrin deficiency is the most common molecular defect in HS. The clinical severity and biochemical expression is heterogeneous. SDS-PAGE analysis of RBC membrane protein was provided the diagnosis of RBC membrane defects and basic molecular studies. We believed that the early identification of the biochemical defect responsible for HS is important because it is helpful starling point for the identification of the primary molecular defect, and it could help to anticipate the clinical outcome of the disease. For these reasons, we consider the SDS-PAGE of the red cell membrane to be of crucial importance for a complete evaluation of children with HS. Further studies with more cases would be to clarify the correlation between clinical and biochemical phenotypes.