[Hereditary red cell membrane disorders in Japan: comparison with other countries]

Red cell membrane disorders are the most common type of inherited hemolytic disorders in the Japanese population. In hereditary spherocytosis (HS), the primary presentation is a loss of membrane surface area, leading to reduced deformability because of defects in the membrane proteins ankyrin, band 3, β-spectrin, α spectrin, or protein 4.2 (P4.2). Complete P4.2 deficiencies, which are inherited in an autosomal recessive manner, comprise a unique HS subgroup and are common in Japanese, but rare in other populations. In contrast, the principle presentation in hereditary elliptocytosis (HE) is mechanical weakness of the erythrocyte membrane skeleton due to defects in α-spectrin, β-spectrin, or protein 4.1. Although α-spectrin mutations are the most frequent cause of HE in Caucasian, African, and Mediterranean populations, these mutations are rare in the Japanese population, in which P4.1 deficiencies are instead most common. Furthermore, hereditary stomatocytoses (HSt) are disorders of monovalent cation permeability in the red cell membrane.