Neurodegeneration with Brain Iron Accumulation

Clinical Characteristics
Ocular Features: 

Optic atrophy is a major ocular feature and the primary cause of visual impairment.  A minority (25%) of patients also have a diffuse fleck retinopathy with a bull’s eye maculopathy.  Later the retinopathy may resemble retinitis pigmentosa with a bone spicule pattern. Nystagmus is often present.  These signs usually follow systemic signs such as difficulties in locomotion.  An apraxia of eyelid opening has been noted and some patients have blepharospasm. 

Systemic Features: 

This is a progressive disorder of the basal ganglia with prominent symptoms of extrapyramidal dysfunction.  Onset is in early childhood or in the neonatal period with delayed development and sometimes mental retardation.  Choreoathetoid writhing movements, stuttering, dysphagia, muscle rigidity, and intermittent dystonia are prominent features.  Seizures are uncommon.  Older individuals may exhibit dementia and ambulation is eventually impaired.  The MRI usually shows an area of hyperintensity in the medial globus pallidus that has been called the ‘eye of the tiger’ sign but this is not pathognomonic.  Axonal degeneration with accumulation of spheroidal inclusions can be seen histologically. 

Genetics

The title of this disorder ‘neurodegeneration with brain iron accumulation’ actually refers to a group of disorders with somewhat common characteristics.  Pentothenate kinase-associated neurodegeneration or NB1A1 (234200) is  the most common of these. 

Types  NBIA2A (256600) and NBIA2B (610217) are caused by mutations in the PLA2G6 gene (22q13.1).  The former can be seen neonatally but usually has its onset in the first two years of life and is sometimes called infantile neuroaxonal dystrophy or Seitelberger disease.  Death may occur before the age of 10 years.  Signs of motor neuron and cerebellar disease are more prominent than in NB1A1. 

NBIA2B has a later onset (4-5 years) and profound sensorimotor impairment but there are many overlapping features and the nosology is confusing.  Mutations in the FTL gene cause yet another form designated NBIA3 (606159) but ocular signs seem to be absent. 

Treatment
Treatment Options: 

There is evidence that treatment with deferiprone reduces the amount of iron accumulation in the globus pallidus with motor improvement in at least some patients.  Most patients require supportive care.

References
Article Title: 

References

Schneider SA. Neurodegeneration with Brain Iron Accumulation. Curr Neurol Neurosci Rep. 2016 Jan;16(1):9. doi: 10.1007/s11910-015-0608-3.

PubMedID: 26739693

Abbruzzese G, Cossu G, Balocco M, Marchese R, Murgia D, Melis M, Galanello R, Barella S, Matta G, Ruffinengo U, Bonuccelli U, Forni GL. A pilot trial of deferiprone for neurodegeneration with brain iron accumulation. Haematologica. 2011 Jul 26. [Epub ahead of print]

PubMedID: 21791473

Gregory A, Polster BJ, Hayflick SJ. Clinical and genetic delineation of neurodegeneration with brain iron accumulation. J Med Genet. 2009 Feb;46(2):73-80. Review.

PubMedID: 18981035

Kurian MA, Morgan NV, MacPherson L, Foster K, Peake D, Gupta R, Philip SG, Hendriksz C, Morton JE, Kingston HM, Rosser EM, Wassmer E, Gissen P, Maher ER. Phenotypic spectrum of neurodegeneration associated with mutations in the PLA2G6 gene (PLAN). Neurology. 2008 Apr 29;70(18):1623-9.

PubMedID: 18443314

Hayflick SJ, Westaway SK, Levinson B, Zhou B, Johnson MA, Ching KH, Gitschier J. Genetic, clinical, and radiographic delineation of Hallervorden-Spatz syndrome. N Engl J Med. 2003 Jan 2;348(1):33-40.

PubMedID: 12510040

Luckenbach MW, Green WR, Miller NR, Moser HW, Clark AW, Tennekoon G. Ocular clinicopathologic correlation of Hallervorden-Spatz syndrome with acanthocytosis and pigmentary retinopathy. Am J Ophthalmol. 1983 Mar;95(3):369-82.

PubMedID: 6829683