[Characteristics of red cell membrane disorders in the Japanese population]

The characteristic features of the incidence of hereditary red cell membrane disorders in the Japanese population are described, based on our studies on 610 patients from 353 kindreds during 20 years since 1975. These patients were screened by a protocol on red cell morphology (scanning and transmission electron microscopy), red cell membrane proteins (sodium dodecylsulfate polyacrylamide gel electrophoresis, and kinetics of membrane proteins), membrane lipids, biophysical studies (ektacytometry, mechanical stability, and fluorescence recovery after photobleaching method), and membrane transport (sodium influx and efflux, and anion transport). Hereditary spherocytosis (HS) is most frequent (308 patients from 156 kindreds), hereditary elliptocytosis (HE) is the second (98 patients from 47 kindreds) followed by hereditary stomatocytosis (57 patients from 40 kindreds). Among the molecular abnormalities detected, alpha-spectrin mutation in the Japanese HE patients appeared extremely rare (only one family with spectrin alpha 1/74), despite three novel beta-spectrin mutations were found out of nine world-wide cases. Most of the Japanese HE patients were associated with partial protein 4.1 deficiencies. Ankyrin abnormalities in the Japanese HS patients appeared less common than those in the Western countries. Complete protein 4.2 deficiencies (34 patients from 20 kindreds) were unique in the Japanese population. Membrane lipid abnormalities included hereditary high red cell membrane phosphatidylcholine hemolytic anemia (30 patients from 18 kindreds), congenital beta-lipoprotein deficiency (acanthocytosis: seven patients from five kindreds), and each one patient of congenital lecithin: cholesterol acyltransferase deficiency and of congenital alpha-lipoprotein deficiency (Tangier disease).