PLA2G6 and neurodegeneration with brain iron accumulation: PLA2G6-associated neurodegeneration (NBIA/DYT/PARK-PLA2G6) comprises a continuum of three phenotypes with overlapping clinical and radiologic features: infantile neuroaxonal dystrophy (INAD), atypical neuroaxonal dystrophy (atypical NAD), and PLA2G6 -related dystonia-parkinsonism.