PANK2 and hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa, and pallidal degeneration: Furthermore, the clinical overlap described between PKAN and HARP syndrome (hypoprebetalipoproteinaemia, acanthocytosis, retinitis pigmentosa and pallidal degeneration), which both derive from mutations in PANK2, strongly links lipid production deficits in PANK2 mutants [51].