“…Band 4.2 is one of the major membrane proteins in human red cells and constitutes approximately 5% of total membrane proteins [Korsgren and Cohen, 1986Sung et al, 1992;Cohen et al, 19931. Although the detailed function of this protein is unknown, it has been shown that band 4.2 functionally binds strongly to transmembrane protein band 3 (AE-1) and thereby is assumed to play an important role in maintaining the normal structure and function of the cytoskeleta1 network and intramembrane particles (IMPs) [Cohen and Gascard, 1992;Cohen et al, 19931. Since 1974, when the first two reports of band 4.2 deficiency [Hayashi et al, 1974;Nozawa et al, 19741 appeared independently, approximately 30 cases with this disorder have been described [Rybicki et al, 1988;Ghanem et al, 1990;Ideguchi et al, 1990;Iwamoto et al, 1993;Yawata, 1994a,b;Inoue et al, 1994;Takaoka et al, 1994;Hayette et al, 1995a,b;Kanzaki et al, 1995a,b]. These cases demonstrated uncompensated hemolytic anemia, abnormal red cell morphology of either spherocytosis [Yawata, 1994al or ovalostomatocytosis [Yawata, 1994a1, increased osmotic fragility [Yawata, 1994a,b], increased sodium influx and efflux [Yawata, 1994b;Inoue et al, 19941, increased lateral mobility [Yawata, 1994a;Inoue et al, 19941.…”