Red cell membrane disorders in the Japanese population: clinical, biochemical, electron microscopic, and genetic studies.

Based on studies on 610 cases of hereditary red cell membrane disorders, the characteristic features of the incidence of these disorders in the Japanese population are described. These patients were screened by a protocol on red cell morphology (scanning electron microscopy), on red cell membrane proteins (sodium dodecylsulfate polyacrylamide gel electrophoresis, and kinetics of membrane proteins), biophysical studies (ektacytometry, mechanical stability and fluorescence recovery after the photobleaching method), membrane transport (sodium influx and efflux, and anion transport), gene analysis (spectrins, band 4.2 and band 3), surface markers (blood type antigens and sialic acid content), and development and expression of membrane proteins (using a two-phase liquid culture system). Among the molecular abnormalities detected, alpha-spectrin mutation appeared rare (only one family with spectrin alpha I/74), as opposed to two beta-spectrin mutations in Japan out of seven worldwide cases. Two unrelated kindreds with a chromosomal abnormality; that is, del (8) (p11.2-p21.1), were found that involved the possible contribution of ankyrin to the pathogenesis of hereditary spherocytosis. Anomalies of a transmembrane domain of band 3 were detected in two independent kindreds with impaired anion transport. Among 16 HE patients, 13 cases were partially band 4.1 deficient. Complete band 4.2 deficiency of the Nippon type (GCT-->ACT at codon 142 in band 4.2 gene) was observed in 17 cases of 13 unrelated kindreds. Other forms of band 4.2 deficiency without the mutation were also detected in three kindreds. Band 7 deficiency was found in seven cases with hereditary stomatocytosis independent of the presence or absence of cation transport abnormalities. A relatively high incidence of hereditary high red cell membrane phosphatidylcholine hemolytic anemia was disclosed by the analysis of red cell membrane lipids.