PANK2 Mutations Research Articles

Pallidal neuronal apolipoprotein E in pantothenate kinase-associated neurodegeneration recapitulates ischemic injury to the globus pallidus.

Pantothenate kinase-associated neurodegeneration (PKAN) is a progressive movement disorder that is due to mutations in PANK2. Pathologically, it is a member of a class of diseases known as neurodegeneration with brain iron accumulation (NBIA) and features increased tissue iron and ubiquitinated proteinaceous aggregates in the globus pallidus. We have previously determined that these aggregates represent condensed residue derived from degenerated pallidal neurons. However, the protein content, other than ubiquitin, of these aggregates remains unknown. In the present study, we performed biochemical and immunohistochemical studies to characterize these aggregates and found them to be enriched in apolipoprotein E that is poorly soluble in detergent solutions. However, we did not determine a significant association between APOE genotype and the clinical phenotype of disease in our database of 81 cases. Rather, we frequently identified similar ubiquitin- and apolipoprotein E-enriched lesions in these neurons in non-PKAN patients in the penumbrae of remote infarcts that involve the globus pallidus, and occasionally in other brain sites that contain large γ-aminobutyric acid (GABA)ergic neurons. Our findings, taken together, suggest that tissue or cellular hypoxic/ischemic injury within the globus pallidus may underlie the pathogenesis of PKAN.

Dramatic Improvement in Juvenile Parkinsonism after Levodopa Treatment in a Patient Negative for the PANK2 Mutation

Juvenile parkinsonism is a rare movement disorder. In pediatric patients, the manifestations are more complex and varied, which makes the diagnosis challenging. It may occasionally manifest as another disease such as dopa-responsive dystonia, Wilson disease, or neurodegeneration with brain iron accumulation (i.e., HallervordeneSpatz disease). This paper reports a 14-year-old girl who experienced a variety of movement disorders such as parkinsonism and dystonia. Her symptoms changed and worsened within a few years, but dramatically improved with levodopa treatment.

Induction of Neuron-Specific Degradation of Coenzyme A Models Pantothenate Kinase-Associated Neurodegeneration by Reducing Motor Coordination in Mice

BackgroundPantothenate kinase-associated neurodegeneration, PKAN, is an inherited disorder characterized by progressive impairment in motor coordination and caused by mutations in PANK2, a human gene that encodes one of four pantothenate kinase (PanK) isoforms. PanK initiates the synthesis of coenzyme A (CoA), an essential cofactor that plays a key role in energy metabolism and lipid synthesis. Most of the mutations in PANK2 reduce or abolish the activity of the enzyme. This evidence has led to the hypothesis that lower CoA might be the underlying cause of the neurodegeneration in PKAN patients; however, no mouse model of the disease is currently available to investigate the connection between neuronal CoA levels and neurodegeneration. Indeed, genetic and/or dietary manipulations aimed at reducing whole-body CoA synthesis have not produced a desirable PKAN model, and this has greatly hindered the discovery of a treatment for the disease.Objective, Methods, Results and ConclusionsCellular CoA levels are tightly regulated by a balance between synthesis and degradation. CoA degradation is catalyzed by two peroxisomal nudix hydrolases, Nudt7 and Nudt19. In this study we sought to reduce neuronal CoA in mice through the alternative approach of increasing Nudt7-mediated CoA degradation. This was achieved by combining the use of an adeno-associated virus-based expression system with the synapsin (Syn) promoter. We show that mice with neuronal overexpression of a cytosolic version of Nudt7 (scAAV9-Syn-Nudt7cyt) exhibit a significant decrease in brain CoA levels in conjunction with a reduction in motor coordination. These results strongly support the existence of a link between CoA levels and neuronal function and show that scAAV9-Syn-Nudt7cyt mice can be used to model PKAN.

P149 – 2652: Neuroimaging findings in two common NBIA subtypes, PKAN and MPAN

Objective The two most common subtypes of NBIA (neurodegeneration with brain iron accumulation; formerly called as Hallervorden-Spatz syndrome) in Poland are PKAN and MPAN, caused by mutations in PANK2 and C19orf12, respectively. Characteristic findings in brain MRI are valuable to distinguish between different forms of NBIA and perform efficient genetic testing. Methods We evaluated brain MRIs from 41 patients with PKAN and in 30 patients with MPAN. We determined the degree of change in signal intensity in different brain regions with a focus on the basal ganglia and substantia nigra. We performed genetic testing to confirm the presence of mutations in PKAN2 and C19orf12. Results All 41 patients with PKAN showed a specific T2-weighted hyperintensity within a hypointense area in the globus pallidus, described as an eye-of-the-tiger sign. 30 patients with MPAN revealed a hypointense signal in the globus pallidus and in the substantia nigra. Brain MRI in younger patients with PKAN initially revealed only hyperintense signal with surrounding small hypointense signal in globus pallidus. Younger subjects with MPAN revealed only presence of hypointense signal in globus pallidus and in substantia nigra, which size increased with age of the patients. Evaluations performed in patients with PKAN and MPAN demonstrated no other abnormalities in other brain structures. Conclusion Patients with PKAN and MPAN are distinguishable based on characteristic brain MRI patterns, which makes it possible to refer them for molecular evaluation in order to confirm a preliminary diagnosis.

OP8 – 2655: Intraocular pathology in PKAN and MPAN, i.e. main forms of NBIA (formerly Hallervorden-Spatz syndrome)

Objective In the group of neurodegenerative diseases with iron accumulation in the brain (NBIA) two forms have been differentiated, the most common in children, PKAN and MPAN, which are genetic diseases. Mutations in PANK2 and C19orf12 genes cause occurrence of clinical symptoms of this disease, which are different for each form. In PKAN, progressive generalized dystonia is present, and in MPAN, spastic paralysis of the lower limbs occurs. Furthermore, within the course of both diseases, other clinical symptoms are observed in form of cognitive functions disorder, intraocular pathology in the organ of vision, and axonal neuropathy. Methods In case of PKAN, 41 patients (24 boys, 17 girls) in the age of 2–14 years (median 4) underwent clinical evaluation studies within the observation period of 1–18 years and in case of MPAN, the study included 30 patients (20 boys, 10 girls) in the age of 4–14 years (median 10) within the observation period of 2–26 years (median 11 years). The organ of vision was examined and evaluations were conducted in terms of functional evaluation as well as standard exam of the anterior segment and fundus of the eye was performed. Results Performed ophthalmological exams confirmed lesions in form of retinitis pigmentosa with various intensity in 22/41 (53.7%) patients with PKAN. In patients with MPAN, optic nerve atrophy of progressive nature was established in 27/30 (90%) patients and it was always accompanied by lowered visual acuity. Conclusion Obtained results of the ophthalmological exams confirmed occurrence of retinitis pigmentosa in 53% of patients with PKAN, whereas optic nerve atrophy with lowered visual acuity in 90% of patients with MPAN. In both forms of the disease, progressive nature of lesions described in the organ of vision was observed.

Acanthocytosis and the c.680 A>G Mutation in the PANK2 Gene: A Study Enrolling a Cohort of PKAN Patients from the Dominican Republic.

Pantothenate Kinase-Associated Neurodegeneration (PKAN) is a form of Neurodegeneration with Brain Iron Accumulation (NBIA) associated with mutations in the pantothenate kinase 2 gene (PANK2). Pantothenate kinases catalyze the rate-limiting step of coenzyme A synthesis and Pank2 is the only pantothenate kinase isoform in humans that is localized to mitochondria. Acanthocytosis, the occurrence of spiculated erythrocytes, is observed in about 10% of the PKAN patients. Therefore PKAN is also classified together with other rare neurodegenerative diseases like Chorea Acanthocytosis (ChAc) and McLeod syndrome (MLS) into the Neuroacanthocytosis (NA) syndromes. It has not been investigated yet whether acanthocytosis in PKAN is associated with a specific subset of Pank2 mutations. In this study, we analyzed acanthocytosis of a cohort of 25 PKAN patients from the Dominican Republic that are homozygous for the c.680 A>G mutation in the PANK2 gene as compared to control donors that are heterozygous or wild-type with respect to this mutation. 3D modeling of this mutation indicated that the replacement of a tyrosine by a cysteine at position 227 in Pank2 disrupts a polar interaction within the A domain of the enzyme. Mean acanthocyte count was elevated in the cohort of patients, however, acanthocytosis varied among the patients with nearly half of them showing high (>20%) or elevated acanthocytosis and the rest showing mild (6-10%) or no (<6%) acanthocytosis. Heterozygous control donors revealed a tendency to mild acanthocytosis. Based on the insight that Pank2 is a normal constituent of red blood cells and de novo biosynthesis of coenzyme A is likely to take place in the erythrocyte cytosol we propose a hypothetical model that accounts for the variability in the occurrence of acanthocytic cells in PKAN.

Modeling human Coenzyme A synthase mutation in yeast reveals altered mitochondrial function, lipid content and iron metabolism.

Mutations in nuclear genes associated with defective coenzyme A biosynthesis have been identified as responsible for some forms of neurodegeneration with brain iron accumulation (NBIA), namely PKAN and CoPAN. PKAN are defined by mutations in PANK2, encoding the pantothenate kinase 2 enzyme, that account for about 50% of cases of NBIA, whereas mutations in CoA synthase COASY have been recently reported as the second inborn error of CoA synthesis leading to CoPAN. As reported previously, yeast cells expressing the pathogenic mutation exhibited a temperature-sensitive growth defect in the absence of pantothenate and a reduced CoA content. Additional characterization revealed decreased oxygen consumption, reduced activities of mitochondrial respiratory complexes, higher iron content, increased sensitivity to oxidative stress and reduced amount of lipid droplets, thus partially recapitulating the phenotypes found in patients and establishing yeast as a potential model to clarify the pathogenesis underlying PKAN and CoPAN diseases.

Mitochondria: A crossroads for lipid metabolism defect in neurodegeneration with brain iron accumulation diseases

Neurodegeneration with brain iron accumulation (NBIA) comprises a group of brain iron deposition syndromes that lead to mixed extrapyramidal features and progressive dementia. Exact pathologic mechanism of iron deposition in NBIA remains unknown. However, it is becoming increasingly evident that many neurodegenerative diseases are hallmarked by metabolic dysfunction that often involves altered lipid profile. Among the identified disease genes, four encode for proteins localized in mitochondria, which are directly or indirectly implicated in lipid metabolism: PANK2, CoASY, PLA2G6 and C19orf12. Mutations in PANK2 and CoASY, both implicated in CoA biosynthesis that acts as a fatty acyl carrier, lead, respectively, to PKAN and CoPAN forms of NBIA. Mutations in PLA2G6, which plays a key role in the biosynthesis and remodeling of membrane phospholipids including cardiolipin, lead to PLAN. Mutations in C19orf12 lead to MPAN, a syndrome similar to that caused by mutations in PANK2 and PLA2G6. Although the function of C19orf12 is largely unknown, experimental data suggest its implication in mitochondrial homeostasis and lipid metabolism. Altogether, the identified mutated proteins localized in mitochondria and associated with different NBIA forms support the concept that dysfunctions in mitochondria and lipid metabolism play a crucial role in the pathogenesis of NBIA.This article is part of a Directed Issue entitled: Energy Metabolism Disorders and Therapies.

Analysis of the C19orf12 and WDR45 genes in patients with neurodegeneration with brain iron accumulation

BackgroundNeurodegeneration with brain iron accumulation (NBIA) comprises a clinically and genetically heterogeneous group of diseases presenting with movement disorders and brain iron deposits. In addition to NBIA subtypes caused by mutations in PANK2 and PLA2G6, mutations in the C19orf12 gene were recently described as the third frequent cause of NBIA (called mitochondrial membrane protein-associated neurodegeneration, MPAN). Additionally, the X-linked gene WDR45 was found causative for a special subtype named static encephalopathy in childhood with neurodegeneration in adulthood (also called BPAN); however, analysis of this gene in a broader spectrum of NBIA has not been reported yet. MethodsIn a heterogeneous cohort of 69 patients with suspected NBIA that did not carry mutations in PANK2 and PLA2G6, the coding region of C19orf12 was evaluated by Sanger sequencing. The WDR45 gene was analyzed via high resolution melting and subsequent sequence analysis. ResultsPreviously described homozygous C19orf12 mutations were found in 3/69 NBIA patients (4.3%). Analysis of the WDR45 gene revealed a novel heterozygous missense mutation in one female NBIA patient showing psychomotor retardation with secondary decline. ConclusionsC19orf12 mutations were confirmed in our heterogeneous NBIA cohort, while WDR45 mutations appear to be restricted to the subtype showing encephalopathy in childhood with neurodegeneration in adulthood.

7-Tesla Magnetic Resonance Imaging for Brain Iron Quantification in Homozygous and Heterozygous PANK2 Mutation Carriers.

Pantothenate-kinase-associated neurodegeneration (PKAN) is an autosomal recessive disorder characterized by iron deposits in basal ganglia. The aim of this study was to quantify iron concentrations of deep gray matter structures in heterozygous PANK2 mutation carriers and in PKAN patients using quantitative susceptibility mapping MRI. By determining iron concentration, we intended to find mutation-specific brain parenchymal stigmata in heterozygous PANK2 mutation carriers in comparison to age-matched healthy volunteers. We studied 11 heterozygous PANK2 gene mutation carriers (mean age: 43.4 years; standard deviation [SD]: 10.5), who were found to be clinically asymptomatic by neurological examination. These carriers were compared to 2 clinically affected PKAN patients 21 and 32years of age and to 13 age-matched, healthy controls (mean age: 39.7; SD, 13.6). Scanning was performed on a 7.0-Tesla whole-body scanner applying three-dimensional susceptibility-weighted gradient echo acquisitions. Susceptibility maps were calculated by threshold-based k-space division with single-orientation acquisition. Magnetic susceptibility values, relative to the occipital white matter, were determined for the following regions of interest (ROI): globus pallidus (GP), thalamus, putamen, internal capsule (IC), caudate nucleus, substantia nigra (SN), and red nucleus. Heterozygous PANK2 mutation carriers did not show increased brain iron concentrations, compared to healthy controls (P>0.05), in any of the examined ROIs. In PKAN patients, more than 3 times higher concentrations of iron were found in the GP, SN, and IC. Our results suggest that heterozygous mutations in PANK2 gene do not cause brain iron accumulation nor do they cause movement disorders.

Defective pantothenate metabolism and neurodegeneration.

Inborn errors of CoA (coenzyme A) biosynthesis lead to neurodegenerative disorders in humans. PKAN (pantothenate kinase-associated neurodegeneration) manifests with damage to brain, retina and testis and is caused by mutations in PANK2, the gene encoding the mitochondrial form of pantothenate kinase, a key regulatory enzyme in CoA synthesis. Further attention has been focused on this pathway by the recent discovery that mutations in the gene encoding CoA synthase lead to a similar neurodegenerative disorder, raising the spectre of a common mechanism of pathogenesis. How do defects in CoA production result in neurodegeneration? Why are certain tissues and cell types selectively vulnerable? And what is the underlying neurodegenerative process? Answers to some of these questions have come from animal models of disease, including flies and mice, as well as directly from humans. The damaged tissue types share key features that are likely to contribute to their selective vulnerability. These include the presence of a blood-tissue barrier, the milieu with respect to oxidative stress, tissue metabolic demand, relative expression of genes encoding similar proteins in these tissues and cell membrane composition. Substantial progress in understanding these important neurometabolic disorders has been made since the first gene discovery more than a decade ago. With rational therapeutics now in development for PKAN, we foresee prevention of neurodegeneration and hope for neuroregeneration or neuro-rescue.

Clinical, imaging, and molecular findings in a sample of Mexican families with pantothenate kinase‐associated neurodegeneration

Pantothenate kinase-associated neurodegeneration (PKAN) is an autosomal recessive disorder characterized by iron accumulation in the brain, because of mutations in the PANK2 gene. Phenotypic and genotypic characteristics of 11 patients from five Mexican families with PKAN disease are reported. Sequencing of PANK2 confirmed the diagnosis. The 11 patients had dysarthria associated with dystonia and Parkinsonism in six. Brain magnetic resonance imaging (MRI) showed the 'eye-of-the-tiger' sign in all patients. Three different mutations were identified, a novel one (p.A469P) and two (p.G219V and p.N404I) very rare. Homozygous sibs for the p.G219V mutation had a severe disease progression with early death. Dystonia predominated in the p.A469P/p.N404I compound heterozygous patients. Homozygous for p.N404I showed Parkinsonism, tics and personality and speech disorders. Early and late disease onset and variable expression was present in carriers of the different identified mutations. The 'eye-of-the-tiger' is an excellent neuroimaging hallmark to predict PANK2 mutations. We detected a 'cluster' of patients harboring the p.N404I mutation, strongly suggesting a founder effect for this mutation. This is the first familial clinical-genetic PKAN disease study accomplished in Mexico.

Ophthalmic features of PLA2G6-related paediatric neurodegeneration with brain iron accumulation

BackgroundNeurodegeneration with brain iron accumulation (NBIA) refers to genetically heterogenous paediatric neurodegenerative disorders characterised by basal ganglia iron deposition. One major cause is recessive mutations in the PLA2G6 gene. While...

Neurodegeneration with Brain Iron Accumulation in an Eleven-Year-Old Jamaican Male

We present a case of an eleven-year-old boy presenting with progressive extrapyramidal signs and dementia. His imaging findings demonstrated the classic eye-of-the-tiger sign on T2W magnetic resonance imaging. He was diagnosed with pantothenate kinase-associated neurodegeneration (PKAN). This is a rare autosomal recessive inborn error of coenzyme A metabolism, caused by mutations in PANK2. This is the first reported case of PKAN from the Caribbean.

Newly Characterized Forms of Neurodegeneration with Brain Iron Accumulation

Neurodegeneration with brain iron accumulation (NBIA) comprises a group of brain iron deposition syndromes that lead to mixed extrapyramidal features and progressive dementia. Historically, there has not been a clearly identifiable molecular cause for many patients with clinical and radiologic features of NBIA. Recent discoveries have shown that mutations in C19orf12 or WDR45 can lead to NBIA. C19orf12 mutations are inherited in an autosomal recessive manner, and lead to a syndrome similar to that caused by mutations in PANK2 or PLA2G6. In contrast, WDR45 mutations lead to a distinct form of NBIA characterized by spasticity and intellectual disability in childhood followed by the subacute onset of dystonia-parkinsonism in adulthood. WDR45 mutations act in an X-linked dominant manner. Although the function of C19orf12 is largely unknown, WDR45 plays a key role in autophagy. Each of these new forms of NBIA thus leads to a distinct clinical syndrome, and together they implicate new cellular pathways in the pathogenesis of these disorders.

Exome sequencing in 30 neurodegeneration with brain iron accumulation patients

Aims: The three major clinically distinct forms of neurodegeneration with brain iron accumulation (NBIA), PKAN (PANK2 mutations), MPAN (C19orf12 mutations), and PLAN (PLA2G6 mutations) account for approximately 70% of cases. Few others are explained by the rare minor NBIA forms but a meaningful number remains undiagnosed.

PANK2 disease with early onset: clinical and radiologic findings under short term treatment with deferiprone

Case report: PANK2 disease belongs to a group of neurodegenerative diseases with brain iron accumulation (NBIA) comprising of several biochemically and genetically heterogeneous diseases. Till date seven genes are identified. In approximately 50% of all NBIA cases a mutation in the panthotenatekinase-gene is detected and presence of the eye of the tiger sign should prompt genetic testing for PANK2 mutations. Clinical signs occur from early childhood to adulthood with gait disturbances, dysarthria, and rapid progressive dystonia. Therapeutic options consist of palliative interventions. Since 2007 treatment with iron chelating agents as deferiprone has been studied in small patient cohorts. Results are ambiguous.

Chapter Two - Pantothenate Kinase-Associated Neurodegeneration (PKAN) and PLA2G6-Associated Neurodegeneration (PLAN): Review of Two Major Neurodegeneration with Brain Iron Accumulation (NBIA) Phenotypes

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.

A novel PANK2 mutation in a 12-year-old Chinese boy with pantothenate kinase-associated neurodegeneration

A novel PANK2 mutation in a 12-year-old Chinese boy with pantothenate kinase-associated neurodegeneration

PANK2 and C19orf12 mutations are common causes of neurodegeneration with brain iron accumulation

Neurodegeneration with brain iron accumulation (NBIA) constitutes a group of neurodegenerative disorders with pronounced iron deposition in the basal ganglia. PANK2 mutations are the most common cause of these disorders. C19orf12 was recently reported as another causative gene. We present phenotypic data and results of screening of PANK2 and C19orf12 in 11 unrelated Iranian NBIA patients. Phenotypic data were obtained by neurologic examination, magnetic resonance imaging, and interviews. Mutation screening of PANK2 and C19orf12 was performed by sequencing. PANK2 and C19orf12 mutations were found in 7 and 4 patients, respectively. Phenotypic comparisons suggest that C19orf12 mutations as compared with PANK2 mutations result in a milder disease course. Mutations in both PANK2 and C19orf12 contributed significantly to NBIA in the Iranian patients. To the best of our knowledge, this is the first genetic analysis reported on a cohort of NBIA patients from the Middle East.