HARP (hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa, and pallidal degeneration) is a rare syndrome with many clinical similarities to pantothenate kinase associated neurodegeneration (PKAN). Both HARP and PKAN are caused by mutations in the gene encoding pantothenate kinase 2 (PANK2). HARP is distinguished by a specific lipoprotein abnormality. Patients have decreased or absent pre-beta lipoproteins consisting of very-low-density lipoproteins (VLDL).
