Chorea-acanthocytosis: clinical and genetic findings in three families from the Arabian peninsula.

Chorea-acanthocytosis is a rare autosomal recessive disorder. Its characteristics are orofacial dyskinesia, hyporeflexia, seizures, aberrant behavior, atrophy of the caudate and putamen, and acanthocytes in the blood with a normal level of lipoproteins. We describe three families with chorea-acanthocytosis. The inheritance pattern was recessive and the average age at onset was 27 years (range, 18-35 years). The presenting symptoms were seizures, aberrant behaviour, chorea, tics, and/or abnormal gait. Phase-contrast and electron microscopy examinations of blood showed 10 to 40% acanthocytes. The lipid profile was normal except that, in one family, no prebetalipoprotein bands corresponding to the fraction of very low-density lipoprotein were seen in high-resolution lipoprotein electrophoresis. Magnetic resonance imaging of the brain showed marked atrophy in the caudate and putamen; 18-fluorodeoxyglucose positron emission tomography scan showed hypometabolism in the striatum. In all three families, the disease was linked to a 6-cM region of chromosome 9q21 flanked by the recombinant markers GATA 89a11 and D9S1843. This finding strongly suggests the involvement of a single locus for this syndrome. Three different homozygous mutations of this gene have been identified. Although the clinical presentation was variable, the genetic studies on these three Saudi Arabian families with chorea-acanthocytosis provide strong evidence for a genetic locus for chorea-acanthocytosis at chromosome 9q21.