HARP syndrome is allelic with pantothenate kinase–associated neurodegeneration

Abstract—HARP (hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa, and pallidal degeneration) is a rare syndrome with many clinical similarities to pantothenate kinase–associated neurodegeneration (PKAN, formerly Hallervorden–Spatz syndrome). Despite these common features, lipoprotein abnormalities have not been reported in PKAN. After the recent discovery of the genetic defect in PKAN, we report a homozygous nonsense mutation in exon 5 of the PANK2 gene that creates a stop codon at amino acid 371 (R371X) in the original HARP patient. This finding establishes that HARP is part of the PKAN disease spectrum.