3181 Sw Sam Jackson Park Rd Attn: Glenda Benton, L103a
Portland OR 97239
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Pallidal neuronal apolipoprotein E in pantothenate kinase-associated neurodegeneration recapitulates ischemic injury to the globus pallidus. - Molecular genetics and metabolism
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 Î³-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.Copyright Â© 2015. Published by Elsevier Inc.
Extracellular 4'-phosphopantetheine is a source for intracellular coenzyme A synthesis. - Nature chemical biology
The metabolic cofactor coenzyme A (CoA) gained renewed attention because of its roles in neurodegeneration, protein acetylation, autophagy and signal transduction. The long-standing dogma is that eukaryotic cells obtain CoA exclusively via the uptake of extracellular precursors, especially vitamin B5, which is intracellularly converted through five conserved enzymatic reactions into CoA. This study demonstrates an alternative mechanism that allows cells and organisms to adjust intracellular CoA levels by using exogenous CoA. Here CoA was hydrolyzed extracellularly by ectonucleotide pyrophosphatases to 4'-phosphopantetheine, a biologically stable molecule able to translocate through membranes via passive diffusion. Inside the cell, 4'-phosphopantetheine was enzymatically converted back to CoA by the bifunctional enzyme CoA synthase. Phenotypes induced by intracellular CoA deprivation were reversed when exogenous CoA was provided. Our findings answer long-standing questions in fundamental cell biology and have major implications for the understanding of CoA-related diseases and therapies.
Novel WDR45 Mutation and Pathognomonic BPAN Imaging in a Young Female With Mild Cognitive Delay. - Pediatrics
Î²-propeller protein-associated neurodegeneration (BPAN) is a recently identified X-linked dominant form of neurodegeneration with brain iron accumulation caused by mutations in the WDR45 gene. BPAN commonly presents as global developmental delay in childhood with rapid onset of parkinsonism and dementia in early adulthood and associated pathognomonic changes seen on brain MRI. In this case report, we present a pediatric patient with mild cognitive delay and pathognomonic MRI changes indicative of BPAN preceding neurologic deterioration who is found to have a novel de novo mutation in the WDR45 gene.Copyright Â© 2015 by the American Academy of Pediatrics.
Neurodegeneration with Brain Iron Accumulation: Genetic Diversity and Pathophysiological Mechanisms. - Annual review of genomics and human genetics
Neurodegeneration with brain iron accumulation (NBIA) comprises a heterogeneous group of progressive disorders with the common feature of excessive iron deposition in the brain. Over the last decade, advances in sequencing technologies have greatly facilitated rapid gene discovery, and several single-gene disorders are now included in this group. Identification of the genetic bases of the NBIA disorders has advanced our understanding of the disease processes caused by reduced coenzyme A synthesis, impaired lipid metabolism, mitochondrial dysfunction, and defective autophagy. The contribution of iron to disease pathophysiology remains uncertain, as does the identity of a putative final common pathway by which the iron accumulates. Ongoing elucidation of the pathogenesis of each NBIA disorder will have significant implications for the identification and design of novel therapies to treat patients with these disorders.
Mutations in RAB39B cause X-linked intellectual disability and early-onset Parkinson disease with Î±-synuclein pathology. - American journal of human genetics
Advances in understanding the etiology of Parkinson disease have been driven by the identification of causative mutations in families. Genetic analysis of an Australian family with three males displaying clinical features of early-onset parkinsonism and intellectual disability identified a âˆ¼45 kb deletion resulting in the complete loss of RAB39B. We subsequently identified a missense mutation (c.503C>A [p.Thr168Lys]) in RAB39B in an unrelated Wisconsin kindred affected by a similar clinical phenotype. In silico and inÂ vitro studies demonstrated that the mutation destabilized the protein, consistent with loss of function. InÂ vitro small-hairpin-RNA-mediated knockdown of Rab39b resulted in a reduction in the density of Î±-synuclein immunoreactive puncta in dendritic processes of cultured neurons. In addition, in multiple cell models, we demonstrated that knockdown of Rab39b was associated with reduced steady-state levels of Î±-synuclein. Post mortem studies demonstrated that loss of RAB39B resulted in pathologically confirmed Parkinson disease. There was extensive dopaminergic neuron loss in the substantia nigra and widespread classic Lewy body pathology. Additional pathological features included cortical Lewy bodies, brain iron accumulation, tau immunoreactivity, and axonal spheroids. Overall, we have shown that loss-of-function mutations in RAB39B cause intellectual disability and pathologically confirmed early-onset Parkinson disease. The loss of RAB39B results in dysregulation of Î±-synuclein homeostasis and a spectrum of neuropathological features that implicate RAB39B in the pathogenesis of Parkinson disease and potentially other neurodegenerative disorders.Copyright Â© 2014 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.
Defective pantothenate metabolism and neurodegeneration. - Biochemical Society transactions
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.
Late diagnosis of fucosidosis in a child with progressive fixed dystonia, bilateral pallidal lesions and red spots on the skin. - European journal of paediatric neurology : EJPN : official journal of the European Paediatric Neurology Society
Fucosidosis is a rare lysosomal storage disease. A 14-year-old girl is presented, with recurrent infections, progressive dystonic movement disorder and mental retardation with onset in early childhood. The clinical picture was also marked by mild morphologic features, but absent dysostosis multiplex and organomegaly. MRI images at 6.5 years of age were reminiscent of pallidal iron deposition ("eye-of-the-tiger" sign) seen in neurodegeneration with brain iron accumulation (NBIA) disorders. Progressively spreading angiokeratoma corporis diffusum led to the correct diagnosis. This case extends the scope of clinical and neuroradiological manifestations of fucosidosis.Copyright Â© 2014 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.
Exome sequence reveals mutations in CoA synthase as a cause of neurodegeneration with brain iron accumulation. - American journal of human genetics
Neurodegeneration with brain iron accumulation (NBIA) comprises a clinically and genetically heterogeneous group of disorders with progressive extrapyramidal signs and neurological deterioration, characterized by iron accumulation in the basal ganglia. Exome sequencing revealed the presence of recessive missense mutations in COASY, encoding coenzyme A (CoA) synthase in one NBIA-affected subject. A second unrelated individual carrying mutations in COASY was identified by Sanger sequence analysis. CoA synthase is a bifunctional enzyme catalyzing the final steps of CoA biosynthesis by coupling phosphopantetheine with ATP to form dephospho-CoA and its subsequent phosphorylation to generate CoA. We demonstrate alterations in RNA and protein expression levels of CoA synthase, as well as CoA amount, in fibroblasts derived from the two clinical cases and in yeast. This is the second inborn error of coenzyme A biosynthesis to be implicated in NBIA.Copyright Â© 2014 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.
BPAN: the only X-linked dominant NBIA disorder. - International review of neurobiology
Beta-propeller protein-associated neurodegeneration (BPAN) is the most recently identified subtype of neurodegeneration with brain iron accumulation (NBIA), being unique with respect to the underlying disease genetics, the associated clinical presentation, and the suggested pathomechanism. Mutations in X-chromosomal WDR45 arise de novo; however, the dominant pattern of inheritance is unusual for an X-linked disorder and additional mechanisms such as X-inactivation or somatic mosaicism are likely to contribute to the phenotype that is indistinguishable between males and females. The course of the disease is two-staged with developmental delay and intellectual disability in childhood and a second phase of rapid neurological deterioration characterized by parkinsonism and dementia occurring in adolescence or early adulthood. At this time, neuroimaging findings are characteristic and provide excellent diagnostic guidance. There is increasing evidence that human WDR45 deficiency impairs autophagy, thereby raising the possibility that this rare disorder will offer insights into more common neurodegenerative disorders such as Parkinson or Alzheimer disease.Â© 2013 Elsevier Inc. All rights reserved.
Pantothenate kinase-associated neurodegeneration (PKAN) and PLA2G6-associated neurodegeneration (PLAN): review of two major neurodegeneration with brain iron accumulation (NBIA) phenotypes. - International review of neurobiology
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.Â© 2013 Elsevier Inc. All rights reserved.
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