SLC4A1 and southeast Asian ovalocytosis: Although heterozygous SAO is apparently asymptomatic in adults, we observed a multinuclear phenotype in cultured heterozygous SAO erythroblasts (albeit to a lesser degree than homozygous erythroblasts), altered protein trafficking and impaired reticulocyte maturation and changes in the membrane protein composition of mature heterozygous SAO RBCs including oxidative damage.