South-east Asian ovalocytosis and the cryohydrocytosis form of hereditary stomatocytosis show virtually indistinguishable cation permeability defects.
The hereditary stomatocytoses are a group of dominantly inherited conditions in which the osmotic stability of the red cell is compromised by abnormally high cation permeability. This report demonstrates the very marked similarities between the cryohydrocytosis form of hereditary stomatocytosis and the common tropical condition south-east Asian ovalocytosis (SAO). We report two patients, one showing a novel cryohydrocytosis variant (Ser762Arg in SLC4A1) and a case of SAO. Both cases showed a mild haemolytic state with some stomatocytes on the blood film, abnormal intracellular sodium and potassium levels which were made markedly abnormal by storage of blood at 0°C, increased cation 'leak' fluxes at 37°C and increased Na(+) K(+) pump activity. In both cases, the anion exchange function of the mutant band 3 was destroyed. Extensive electrophysiological studies comparing the cation leak and conductance in Xenopus laevis oocytes expressing the two mutant genes showed identical patterns of abnormality. These data are consistent with the cryohydrocytosis form of hereditary stomatocytosis and we conclude that the cation leak in SAO is indistinguishable from that in cryohydrocytosis, and that SAO should be considered to be an example of hereditary stomatocytosis.
Laboratoire de biologie et physiopathologie des systèmes intégrés, Université de Nice CNRS, Nice Cedex 2, France.
Hélène
H
Guizouarn
Franck
F
Borgese
Nicole
N
Gabillat
Penny
P
Harrison
Jeroen S
JS
Goede
Corrina
C
McMahon
Gordon W
GW
Stewart
Lesley J
LJ
Bruce
D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics; D002463:Cell Membrane Permeability / Q000502:physiology; D018076:DNA, Complementary / Q000235:genetics; D004912:Erythrocytes / Q000502:physiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006947:Hyperkalemia / Q000097:blood / Q000151:congenital / Q000235:genetics; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D010375:Pedigree; D011188:Potassium / Q000032:analysis; D012964:Sodium / Q000032:analysis; D014982:Xenopus laevis
D001457:Anion Exchange Protein 1, Erythrocyte; D018076:DNA, Complementary; C454201:SLC4A1 protein, human; D012964:Sodium; D011188:Potassium