From OMIM
Neurodegeneration with brain iron accumulation (NBIA) is a genetically heterogeneous disorder characterized by progressive iron accumulation in the basal ganglia and other regions of the brain, resulting in extrapyramidal movements, such as parkinsonism and dystonia. Age at onset, severity, and cognitive involvement are variable (review by Gregory et al., 2009). NBIA1, or pantothenate kinase-associated neurodegeneration (PKAN), has been classified clinically as 'classic,' 'atypical,' or 'intermediate.' In the classic form, patients present within the first decade of life with rapidly progressing disease and loss of ambulation approximately 15 years later. In the atypical form, patients have onset in the second decade with slow progression and maintain independent ambulation after 15 years. In the intermediate form, patients have early onset and slow progression or later onset and rapid progression. Patients with early onset tend to develop pigmentary retinopathy, whereas those with later onset tend to have speech disorders and psychiatric features. Most patients have the 'eye of the tiger' sign on brain MRI, although that finding is not pathognomonic for PANK2 mutations (Hayflick et al., 2003; Pellecchia et al., 2005; Kumar et al., 2006). Genetic Heterogeneity of Neurodegeneration with Brain Iron Accumulation Neurodegeneration with brain iron accumulation is an umbrella term that encompasses a group of genetically heterogeneous disorders. See also NBIA2A (256600) and NBIA2B (610217), both caused by mutation in the PLA2G6 gene (603604); NBIA3 (606159), caused by mutation in the FTL gene (134790); NBIA4 (614298), caused by mutation in the C19ORF12 gene (614297); NBIA5 (300894), caused by mutation in the WDR45 gene (300526); NBIA6 (615643), caused by mutation in the COASY gene (609855); NBIA7 (617916), caused by mutation in the REPS1 gene (614825); NBIA8 (617917), caused by mutation in the CRAT gene (600184); NBIA9 (620669), caused by mutation in the FTH1 gene (134770); and NBIA10 (604290), caused by mutation in the CP gene (117700). There are additional disorders in which brain iron accumulation is observed; see, e.g., Kufor-Rakeb disease (606693), aceruloplasminemia (604290), and SPG35 (612319). Gregory et al. (2009) and Schneider and Bhatia (2012) provided reviews of the different forms of neurodegeneration with brain iron accumulation.  http://www.omim.org/entry/234200

From MedlinePlus Genetics
Pantothenate kinase-associated neurodegeneration (formerly called Hallervorden-Spatz syndrome) is a disorder of the nervous system. This condition is characterized by progressive difficulty with movement, typically beginning in childhood. Movement abnormalities include involuntary muscle spasms, rigidity, and trouble with walking that worsens over time. Many people with this condition also develop problems with speech (dysarthria), and some develop vision loss. Additionally, affected individuals may experience a loss of intellectual function (dementia) and psychiatric symptoms such as behavioral problems, personality changes, and depression.

Pantothenate kinase-associated neurodegeneration is characterized by an abnormal buildup of iron in certain areas of the brain. A particular change called the eye-of-the-tiger sign, which indicates an accumulation of iron, is typically seen on magnetic resonance imaging (MRI) scans of the brain in people with this disorder.

Researchers have described classic and atypical forms of pantothenate kinase-associated neurodegeneration. The classic form usually appears in early childhood, causing severe problems with movement that worsen rapidly. Features of the atypical form appear later in childhood or adolescence and progress more slowly. Signs and symptoms vary, but the atypical form is more likely than the classic form to involve speech defects and psychiatric problems.

A condition called HARP (hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa, and pallidal degeneration) syndrome, which was historically described as a separate syndrome, is now considered part of pantothenate kinase-associated neurodegeneration.   https://medlineplus.gov/genetics/condition/pantothenate-kinase-associated-neurodegeneration