Publications by authors named "Barbara Csanyi"

4 Publications

  • Page 1 of 1

Urine proteomics analysis of patients with neuronal ceroid lipofuscinoses.

iScience 2021 Feb 31;24(2):102020. Epub 2020 Dec 31.

Inborn Errors of Metabolism Section, Genetics & Genomic Medicine Unit, Great Ormond Street Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.

The neuronal ceroid lipofuscinoses (NCL) are a group of 13 rare neurodegenerative disorders characterized by accumulation of cellular storage bodies. There are few therapeutic options, and existing tests do not monitor disease progression and treatment response. However, urine biomarkers could address this need. Proteomic analysis of CLN2 patient urine revealed activation of immune response pathways and pathways associated with the unfolded protein response. Analysis of CLN5 and CLN6 sheep model urine showed subtle changes. To confirm and investigate the relevance of candidate biomarkers a targeted LC-MS/MS proteomic assay was created. We applied this assay to additional CLN2 samples as well as other patients with NCL (CLN1, CLN3, CLN5, CLN6, and CLN7) and demonstrated that hexosaminidase-A, aspartate aminotransferase-1, and LAMP1 are increased in NCL samples and betaine-homocysteine S-methyltransferase-1 was specifically increased in patients with CLN2. These proteins could be used to monitor the effectiveness of future therapies aimed at treating systemic NCL disease.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
February 2021

DNAJC6 Mutations Disrupt Dopamine Homeostasis in Juvenile Parkinsonism-Dystonia.

Mov Disord 2020 08 30;35(8):1357-1368. Epub 2020 May 30.

Molecular Neurosciences, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, London, United Kingdom.

Background: Juvenile forms of parkinsonism are rare conditions with onset of bradykinesia, tremor and rigidity before the age of 21 years. These atypical presentations commonly have a genetic aetiology, highlighting important insights into underlying pathophysiology. Genetic defects may affect key proteins of the endocytic pathway and clathrin-mediated endocytosis (CME), as in DNAJC6-related juvenile parkinsonism.

Objective: To report on a new patient cohort with juvenile-onset DNAJC6 parkinsonism-dystonia and determine the functional consequences on auxilin and dopamine homeostasis.

Methods: Twenty-five children with juvenile parkinsonism were identified from a research cohort of patients with undiagnosed pediatric movement disorders. Molecular genetic investigations included autozygosity mapping studies and whole-exome sequencing. Patient fibroblasts and CSF were analyzed for auxilin, cyclin G-associated kinase and synaptic proteins.

Results: We identified 6 patients harboring previously unreported, homozygous nonsense DNAJC6 mutations. All presented with neurodevelopmental delay in infancy, progressive parkinsonism, and neurological regression in childhood. I-FP-CIT SPECT (DaTScan) was performed in 3 patients and demonstrated reduced or absent tracer uptake in the basal ganglia. CSF neurotransmitter analysis revealed an isolated reduction of homovanillic acid. Auxilin levels were significantly reduced in both patient fibroblasts and CSF. Cyclin G-associated kinase levels in CSF were significantly increased, whereas a number of presynaptic dopaminergic proteins were reduced.

Conclusions: DNAJC6 is an emerging cause of recessive juvenile parkinsonism-dystonia. DNAJC6 encodes the cochaperone protein auxilin, involved in CME of synaptic vesicles. The observed dopamine dyshomeostasis in patients is likely to be multifactorial, secondary to auxilin deficiency and/or neurodegeneration. Increased patient CSF cyclin G-associated kinase, in tandem with reduced auxilin levels, suggests a possible compensatory role of cyclin G-associated kinase, as observed in the auxilin knockout mouse. DNAJC6 parkinsonism-dystonia should be considered as a differential diagnosis for pediatric neurotransmitter disorders associated with low homovanillic acid levels. Future research in elucidating disease pathogenesis will aid the development of better treatments for this pharmacoresistant disorder. © 2020 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
August 2020

Consensus clinical management guideline for pantothenate kinase-associated neurodegeneration (PKAN).

Mol Genet Metab 2017 03 27;120(3):278-287. Epub 2016 Dec 27.

Department of Molecular & Medical Genetics, Oregon Health & Science University, Portland, USA; Department of Neurology, Oregon Health & Science University, Portland, USA.

View Article and Find Full Text PDF

Download full-text PDF

Source Listing
March 2017

Identification of an unusual variant peroxisome biogenesis disorder caused by mutations in the PEX16 gene.

J Med Genet 2010 Sep 20;47(9):608-15. Epub 2010 Jul 20.

Academic Medical Centre, University of Amsterdam, Laboratory Genetic Metabolic Diseases, Department of Paediatrics/Emma Children's Hospital, Amsterdam, The Netherlands.

Background: Zellweger syndrome spectrum disorders are caused by mutations in any of at least 12 different PEX genes. This includes PEX16, which encodes an integral peroxisomal membrane protein involved in peroxisomal membrane assembly. PEX16-defective patients have been reported to have a severe clinical presentation. Fibroblasts from these patients displayed a defect in the import of peroxisomal matrix and membrane proteins, resulting in a total absence of peroxisomal remnants.

Objective: To report on six patients with an unexpected mild variant peroxisome biogenesis disorder due to mutations in the PEX16 gene. Patients presented in the preschool years with progressive spastic paraparesis and ataxia (with a characteristic pattern of progressive leucodystrophy and brain atrophy on MRI scan) and later developed cataracts and peripheral neuropathy. Surprisingly, their fibroblasts showed enlarged, import-competent peroxisomes.

Results: Plasma analysis revealed biochemical abnormalities suggesting a peroxisomal disorder. Biochemical variables in fibroblasts were only mildly abnormal or within the normal range. Immunofluorescence microscopy revealed the presence of import-competent peroxisomes, which were increased in size but reduced in number. Subsequent sequencing of all known PEX genes revealed five novel apparent homozygous mutations in the PEX16 gene.

Conclusions: An unusual variant peroxisome biogenesis disorder caused by mutations in the PEX16 gene, with a relatively mild clinical phenotype and an unexpected phenotype in fibroblasts, was identified. Although PEX16 is involved in peroxisomal membrane assembly, PEX16 defects can present with enlarged import-competent peroxisomes in fibroblasts. This is important for future diagnostics of patients with a peroxisomal disorder.
View Article and Find Full Text PDF

Download full-text PDF

Source Listing
September 2010