Hogarth P, Gregory A, Sanford L, et al. New NBIA subtype: genetic, clinical, pathologic, and radiographic features of MPAN

UHS NHS Foundation Trust (N.C.F., S.R.H.) and Department of Human Genetics and Genomic Medicine, Faculty of Medicine (N.C.F.), University of Southampton, Southampton, UK
Neurology (Impact Factor: 8.29). 12/2012; 80(3). DOI: 10.1212/WNL.0b013e31827e07be
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To assess the frequency of mutations in C19orf12 in the greater neurodegeneration with brain iron accumulation (NBIA) population and further characterize the associated phenotype.

Samples from 161 individuals with idiopathic NBIA were screened, and C19orf12 mutations were identified in 23 subjects. Direct examinations were completed on 8 of these individuals, and medical records were reviewed on all 23. Histochemical and immunohistochemical studies were performed on brain tissue from one deceased subject.

A variety of mutations were detected in this cohort, in addition to the Eastern European founder mutation described previously. The characteristic clinical features of mitochondrial membrane protein-associated neurodegeneration (MPAN) across all age groups include cognitive decline progressing to dementia, prominent neuropsychiatric abnormalities, and a motor neuronopathy. A distinctive pattern of brain iron accumulation is universal. Neuropathologic studies revealed neuronal loss, widespread iron deposits, and eosinophilic spheroidal structures in the basal ganglia. Lewy neurites were present in the globus pallidus, and Lewy bodies and neurites were widespread in other areas of the corpus striatum and midbrain structures.

MPAN is caused by mutations in C19orf12 leading to NBIA and prominent, widespread Lewy body pathology. The clinical phenotype is recognizable and distinctive, and joins pantothenate kinase-associated neurodegeneration and PLA2G6-associated neurodegeneration as one of the major forms of NBIA.

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    • "NBIA syndromes share some clinical findings with NA and Huntington’s Disease [1]. NBIA syndromes are caused by mutations in a number of different genes [1], such as PANK2, responsible for PKAN, or C19orf12 underlying mitochondrial membrane protein-associated neurodegeneration (MPAN) [8,9] In general, acanthocytosis has not been described in NBIA apart from PKAN where roughly 10% of PKAN patients are considered affected. "
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    ABSTRACT: Neuroacanthocytosis (NA) refers to a group of heterogenous, rare genetic disorders, namely chorea acanthocytosis (ChAc), McLeod syndrome (MLS), Huntington's disease-like 2 (HDL2) and pantothenate kinase associated neurodegeneration (PKAN), that mainly affect the basal ganglia and are associated with similar neurological symptoms. PKAN is also assigned to a group of rare neurodegenerative diseases, known as NBIA (neurodegeneration with brain iron accumulation), associated with iron accumulation in the basal ganglia and progressive movement disorder. Acanthocytosis, the occurrence of misshaped erythrocytes with thorny protrusions, is frequently observed in ChAc and MLS patients but less prevalent in PKAN (about 10%) and HDL2 patients. The pathological factors that lead to the formation of the acanthocytic red blood cell shape are currently unknown. The aim of this study was to determine whether NA/NBIA acanthocytes differ in their functionality from normal erythrocytes. Several flow-cytometry-based assays were applied to test the physiological responses of the plasma membrane, namely drug-induced endocytosis, phosphatidylserine exposure and calcium uptake upon treatment with lysophosphatidic acid. ChAc red cell samples clearly showed a reduced response in drug-induced endovesiculation, lysophosphatidic acid-induced phosphatidylserine exposure, and calcium uptake. Impaired responses were also observed in acanthocyte-positive NBIA (PKAN) red cells but not in patient cells without shape abnormalities. These data suggest an "acanthocytic state" of the red cell where alterations in functional and interdependent membrane properties arise together with an acanthocytic cell shape. Further elucidation of the aberrant molecular mechanisms that cause this acanthocytic state may possibly help to evaluate the pathological pathways leading to neurodegeneration.
    PLoS ONE 10/2013; 8(10):e76715. DOI:10.1371/journal.pone.0076715 · 3.23 Impact Factor
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    • "Neurodegeneration with brain iron accumulation (NBIA) encompasses a group of single gene disorders that share the feature of high brain iron. Causative genes have been identified for most patients with NBIA; however, the genetic basis remains to be found for $35% of them (Hogarth et al., 2013). Recently, a new NBIA gene was identified on the X chromosome (Haack et al., 2012). "
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    ABSTRACT: Neurodegenerative disorders with high iron in the basal ganglia encompass an expanding collection of single gene disorders collectively known as neurodegeneration with brain iron accumulation. These disorders can largely be distinguished from one another by their associated clinical and neuroimaging features. The aim of this study was to define the phenotype that is associated with mutations in WDR45, a new causative gene for neurodegeneration with brain iron accumulation located on the X chromosome. The study subjects consisted of WDR45 mutation-positive individuals identified after screening a large international cohort of patients with idiopathic neurodegeneration with brain iron accumulation. Their records were reviewed, including longitudinal clinical, laboratory and imaging data. Twenty-three mutation-positive subjects were identified (20 females). The natural history of their disease was remarkably uniform: global developmental delay in childhood and further regression in early adulthood with progressive dystonia, parkinsonism and dementia. Common early comorbidities included seizures, spasticity and disordered sleep. The symptoms of parkinsonism improved with l-DOPA; however, nearly all patients experienced early motor fluctuations that quickly progressed to disabling dyskinesias, warranting discontinuation of l-DOPA. Brain magnetic resonance imaging showed iron in the substantia nigra and globus pallidus, with a 'halo' of T1 hyperintense signal in the substantia nigra. All patients harboured de novo mutations in WDR45, encoding a beta-propeller protein postulated to play a role in autophagy. Beta-propeller protein-associated neurodegeneration, the only X-linked disorder of neurodegeneration with brain iron accumulation, is associated with de novo mutations in WDR45 and is recognizable by a unique combination of clinical, natural history and neuroimaging features.
    Brain 05/2013; 136(6). DOI:10.1093/brain/awt095 · 9.20 Impact Factor
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    ABSTRACT: Neurodegeneration with brain iron accumulation (NBIA) comprises a heterogeneous group of disorders characterized by the presence of radiologically discernible high brain iron, particularly within the basal ganglia. A number of childhood NBIA syndromes are described, of which two of the major subtypes are pantothenate kinase-associated neurodegeneration (PKAN) and PLA2G6-associated neurodegeneration (PLAN). PKAN and PLAN are autosomal recessive NBIA disorders due to mutations in PANK2 and PLA2G6, respectively. Presentation is usually in childhood, with features of neurological regression and motor dysfunction. In both PKAN and PLAN, a number of classical and atypical phenotypes are reported. In this chapter, we describe the clinical, radiological, and genetic features of these two disorders and also discuss the pathophysiological mechanisms postulated to play a role in disease pathogenesis.
    International Review of Neurobiology 11/2013; 110C:49-71. DOI:10.1016/B978-0-12-410502-7.00003-X · 1.92 Impact Factor
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