PANK1 and abetalipoproteinemia: NA is also found in a smaller percentage of cases with pantothenate kinase-associated neurodegeneration (PKAN), HDL2, and several inherited disorders of lipoprotein metabolism, namely abetalipoproteinemia (Bassen-Kornzweig syndrome) and hypobetalipoproteinemia leading to vitamin E malabsorption (Hayflick et al., 2003; Walker et al., 2003; Jung et al., 2011).