Neurodegeneration with Brain Iron Accumulation (NBIA) refers to a group of rare, inherited neurological disorders characterized by progressive movement abnormalities and excessive iron deposition in the brain.
NBIA encompasses several subtypes, each caused by different genetic mutations. The common feature across all NBIA disorders is the abnormal accumulation of iron in the basal ganglia, which leads to progressive neurological symptoms[1].
Pantothenate Kinase-Associated Neurodegeneration (PKAN), formerly known as Hallervorden-Spatz syndrome, is the most common form of NBIA, accounting for approximately 50% of cases[2]. It is caused by mutations in the PANK2 gene (pantothenate kinase 2), which is involved in coenzyme A biosynthesis[3].
Phospholipase A2, Group VI-Associated Neurodegeneration (PLAN) is caused by mutations in the PLA2G6 gene. This subtype typically presents in early childhood with progressive dystonia and neurodegeneration[4].
NBIA3 is caused by mutations in the COASY gene. It is a rare form with symptoms similar to other NBIA subtypes[5].
Mutations in the FA2H gene can cause a form of NBIA associated with hereditary spastic paraplegia[6].
This X-linked dominant form (β-Propeller Protein-Associated Neurodegeneration, BPAN) is caused by mutations in the WDR45 gene. It primarily affects females and presents with early developmental delay followed by progressive neurodegeneration[7].
All NBIA disorders follow autosomal recessive inheritance, except WDR45-related NBIA which is X-linked dominant. Family history may be negative due to recessive inheritance or de novo mutations[9].
| Subtype | Gene | Inheritance | Key Features |
|---|---|---|---|
| NBIA1 (PKAN) | PANK2 | Autosomal recessive | Most common, early onset |
| NBIA2 (PLAN) | PLA2G6 | Autosomal recessive | Childhood onset, severe |
| NBIA3 | COASY | Autosomal recessive | Rare |
| FA2H-NBIA | FA2H | Autosomal recessive | Spastic paraplegia |
| BPAN | WDR45 | X-linked dominant | Female predominance |
The exact mechanism of iron accumulation in NBIA is not fully understood. In PKAN, loss of PANK2 function leads to decreased coenzyme A levels, which may affect iron metabolism and cause oxidative stress in neurons[10].
Iron accumulation triggers:
Prognosis varies by subtype:
Recent research on Neurodegeneration with Brain Iron Accumulation (NBIA) includes:
Levi S, Finazzi L. Neurodegeneration with brain iron accumulation: update on pathogenic mechanisms and treatment options. Mol Genet Metab. 2014. ↩︎
Zhou B, Westaway SK, Levinson B, Johnson MA, Gitschier J, Hayflick SJ. A novel pantothenate kinase gene (PANK2) is mutated in Hallervorden-Spatz syndrome. Nat Genet. 2001. ↩︎
Santambrogio S, Errea O, Ballabio A, Gawrisch LM, Levi S. Coenzyme A and its thioester derivatives in the brain. Neurochem Res. 2015. ↩︎
Morgan NV, Westaway SK, Gissen P, et al. PLA2G6, encoding a calcium-independent phospholipase A2, causes an early-onset dystonia-parkinsonism syndrome. Nat Genet. 2006. ↩︎
Dusi S, Valletta L, Tiranti V. COQ8A (Coenzyme Q10) deficiency associated with cerebellar ataxia. Handb Clin Neurol. 2023. ↩︎
Dick KJ, Simpson K, Houlden H. FA2H mutations cause a spectrum of leukodystrophies and neurodegeneration. Brain. 2010. ↩︎
Hayflick SJ, Gregory A, Kurian MA. WDR45 mutations in BPAN (beta-propeller protein associated neurodegeneration). J Med Genet. 2013. ↩︎
Kumar N, Rizek P, Jog MS. Neurodegeneration with Brain Iron Accumulation: Update on Pathophysiology and Treatment. Tremor Other Hyperkinet Mov (N Y). 2022. ↩︎
Arber CE, Kleinman G, Love S. Neurodegeneration with Brain Iron Accumulation. Neuropathology. 2020. ↩︎
Zhang J, Lee D. PANK2 and the pathogenesis of neurodegeneration. J Mol Neurosci. 2022. ↩︎
Hayflick SJ, Penzien J, Dure L. MRI "eye-of-the-tiger" sign in PKAN. Neurology. 2003. ↩︎
Tsuboi T, Walz R, Ramirez-Zamora A. Deep brain stimulation for NBIA: systematic review. Neuromodulation. 2023. ↩︎
Zano S, Velez-Rio M, Rutsch F. Iron chelation therapy in NBIA: a systematic review. Orphanet J Rare Dis. 2021. ↩︎