ACANTHOCYTOSIS, RETINITIS-PIGMENTOSA, AND PALLIDAL DEGENERATION - A REPORT OF 3 PATIENTS, INCLUDING THE 2ND REPORTED CASE WITH HYPOPREBETALIPOPROTEINEMIA (HARP-SYNDROME)

We describe an example of a variant of Hallervorden-Spatz disease, characterized by hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa, and pallidal degeneration (HARP syndrome), in an 18-year-old woman who presented with longstanding intellectual subnormality, night blindness, and a 2-year history of orobuccolingual dystonia causing dysarthria and dysphagia. Investigation showed acanthocytosis and hypoprebetalipoproteinemia, and electroretinograms were typical of tapetoretinal degeneration. T-2-weighted MRI show;id decreased signal intensity in the pallidal nuclei with central hyperintensity, constituting the ''eye-of-the-tiger'' sign. The patient's sister and mother have a similar lipid disorder but no retinal or neurologic disease. We also report two patients with clinical and radiologic features similar to those of the patient with HARP syndrome but who had normal lipid studies. These various combinations of components of HARP syndrome may be caused by several distinct genetic diseases or may represent variable manifestations of a contiguous gene defect.