Erythrocyte anion transporter and antibrain immunoreactivity in chorea-acanthocytosis. A contribution to etiology, genetics, and diagnosis.

Novel structural and functional alterations in the erythrocyte anion transporter band 3 are described in one patient with definite, and in two patients with symptoms compatible with chorea-acanthocytosis, but without acanthocytes. Immunoblotting analysis shows increased fragmentation of band 3, and sulfate flux measurements indicate that anion transport activity is reduced in the erythrocytes of these patients. These changes are similar, but not identical to those observed during normal erythrocyte aging. In addition, distinct antibrain immunoreactivity was present in the plasma of these patients. A family study indicates that abnormal erythrocyte band 3 structure and function and antibrain immunoreactivity may be phenotypes of two independent, genetically determined factors, that are part of the heterogenic defect of chorea-acanthocytosis. The findings in the patients without acanthocytes indicate that the biochemical abnormalities may be related to a chorea-acanthocytosis-like, amyotrophic extrapyramidal movement disorder with axonal neuropathy. Measurement of erythrocyte sulfate transport and plasma antibrain immunoreactivity could be of use in establishing the diagnosis and further unravelling the genetic background of chorea-acanthocytosis and related syndromes.