TY  - JOUR
A1  - Mencacci, Niccoló E.
A1  - Isaias, Ioannis U.
A1  - Reich, Martin M.
A1  - Ganos, Christos
A1  - Plagnol, Vincent
A1  - Polke, James M.
A1  - Bras, Jose
A1  - Hersheson, Joshua
A1  - Stamelou, Maria
A1  - Pittman, Alan M.
A1  - Noyce, Alastair J.
A1  - Mok, Kin Y.
A1  - Opladen, Thomas
A1  - Kunstmann, Erdmute
A1  - Hodecker, Sybille
A1  - Münchau, Alexander
A1  - Volkmann, Jens
A1  - Samnick, Samuel
A1  - Sidle, Katie
A1  - Nanji, Tina
A1  - Sweeney, Mary G.
A1  - Houlden, Henry
A1  - Batla, Amit
A1  - Zecchinelli, Anna L.
A1  - Pezzoli, Gianni
A1  - Marotta, Giorgio
A1  - Lees, Andrew
A1  - Alegria, Paulo
A1  - Krack, Paul
A1  - Cormier-Dequaire, Florence
A1  - Lesage, Suzanne
A1  - Brice, Alexis
A1  - Heutink, Peter
A1  - Gasser, Thomas
A1  - Lubbe, Steven J.
A1  - Morris, Huw R.
A1  - Taba, Pille
A1  - Koks, Sulev
A1  - Majounie, Elisa
A1  - Gibbs, J. Raphael
A1  - Singleton, Andrew
A1  - Hardy, John
A1  - Klebe, Stephan
A1  - Bhatia, Kailash P.
A1  - Wood, Nicholas W.
T1  - Parkinson’s disease in GTP cyclohydrolase 1 mutation carriers
JF  - Brain
N2  - GTP cyclohydrolase 1, encoded by the GCH1 gene, is an essential enzyme for dopamine production in nigrostriatal cells. Loss-of-function mutations in GCH1 result in severe reduction of dopamine synthesis in nigrostriatal cells and are the most common cause of DOPA-responsive dystonia, a rare disease that classically presents in childhood with generalized dystonia and a dramatic long-lasting response to levodopa. We describe clinical, genetic and nigrostriatal dopaminergic imaging ([(123)I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) tropane single photon computed tomography) findings of four unrelated pedigrees with DOPA-responsive dystonia in which pathogenic GCH1 variants were identified in family members with adult-onset parkinsonism. Dopamine transporter imaging was abnormal in all parkinsonian patients, indicating Parkinson's disease-like nigrostriatal dopaminergic denervation. We subsequently explored the possibility that pathogenic GCH1 variants could contribute to the risk of developing Parkinson's disease, even in the absence of a family history for DOPA-responsive dystonia. The frequency of GCH1 variants was evaluated in whole-exome sequencing data of 1318 cases with Parkinson's disease and 5935 control subjects. Combining cases and controls, we identified a total of 11 different heterozygous GCH1 variants, all at low frequency. This list includes four pathogenic variants previously associated with DOPA-responsive dystonia (Q110X, V204I, K224R and M230I) and seven of undetermined clinical relevance (Q110E, T112A, A120S, D134G, I154V, R198Q and G217V). The frequency of GCH1 variants was significantly higher (Fisher's exact test P-value 0.0001) in cases (10/1318 = 0.75%) than in controls (6/5935 = 0.1%; odds ratio 7.5; 95% confidence interval 2.4-25.3). Our results show that rare GCH1 variants are associated with an increased risk for Parkinson's disease. These findings expand the clinical and biological relevance of GTP cycloydrolase 1 deficiency, suggesting that it not only leads to biochemical striatal dopamine depletion and DOPA-responsive dystonia, but also predisposes to nigrostriatal cell loss. Further insight into GCH1-associated pathogenetic mechanisms will shed light on the role of dopamine metabolism in nigral degeneration and Parkinson's disease.
KW  - DOPA-responsive-dystonia
KW  - GCH1
KW  - Parkinson's disease
KW  - dopamine
KW  - exome sequencing
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121268
VL  - 137
IS  - 9
ER  - 
TY  - JOUR
A1  - Doll, Julia
A1  - Kolb, Susanne
A1  - Schnapp, Linda
A1  - Rad, Aboulfazl
A1  - Rüschendorf, Franz
A1  - Khan, Imran
A1  - Adli, Abolfazl
A1  - Hasanzadeh, Atefeh
A1  - Liedtke, Daniel
A1  - Knaup, Sabine
A1  - Hofrichter, Michaela AH
A1  - Müller, Tobias
A1  - Dittrich, Marcus
A1  - Kong, Il-Keun
A1  - Kim, Hyung-Goo
A1  - Haaf, Thomas
A1  - Vona, Barbara
T1  - Novel loss-of-function variants in CDC14A are associated with recessive sensorineural hearing loss in Iranian and Pakistani patients
JF  - International Journal of Molecular Sciences
N2  - CDC14A encodes the Cell Division Cycle 14A protein and has been associated with autosomal recessive non-syndromic hearing loss (DFNB32), as well as hearing impairment and infertile male syndrome (HIIMS) since 2016. To date, only nine variants have been associated in patients whose initial symptoms included moderate-to-profound hearing impairment. Exome analysis of Iranian and Pakistani probands who both showed bilateral, sensorineural hearing loss revealed a novel splice site variant (c.1421+2T>C, p.?) that disrupts the splice donor site and a novel frameshift variant (c.1041dup, p.Ser348Glnfs*2) in the gene CDC14A, respectively. To evaluate the pathogenicity of both loss-of-function variants, we analyzed the effects of both variants on the RNA-level. The splice variant was characterized using a minigene assay. Altered expression levels due to the c.1041dup variant were assessed using RT-qPCR. In summary, cDNA analysis confirmed that the c.1421+2T>C variant activates a cryptic splice site, resulting in a truncated transcript (c.1414_1421del, p.Val472Leufs*20) and the c.1041dup variant results in a defective transcript that is likely degraded by nonsense-mediated mRNA decay. The present study functionally characterizes two variants and provides further confirmatory evidence that CDC14A is associated with a rare form of hereditary hearing loss.
KW  - CDC14A
KW  - DFNB32
KW  - autosomal recessive hearing loss
KW  - exome sequencing
KW  - splicing
KW  - frameshift
KW  - non-sense mediated mRNA decay
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-285142
SN  - 1422-0067
VL  - 21
IS  - 1
ER  - 
TY  - JOUR
A1  - Doll, Julia
A1  - Vona, Barbara
A1  - Schnapp, Linda
A1  - Rüschendorf, Franz
A1  - Khan, Imran
A1  - Khan, Saadullah
A1  - Muhammad, Noor
A1  - Alam Khan, Sher
A1  - Nawaz, Hamed
A1  - Khan, Ajmal
A1  - Ahmad, Naseer
A1  - Kolb, Susanne M.
A1  - Kühlewein, Laura
A1  - Labonne, Jonathan D. J.
A1  - Layman, Lawrence C.
A1  - Hofrichter, Michaela A. H.
A1  - Röder, Tabea
A1  - Dittrich, Marcus
A1  - Müller, Tobias
A1  - Graves, Tyler D.
A1  - Kong, Il-Keun
A1  - Nanda, Indrajit
A1  - Kim, Hyung-Goo
A1  - Haaf, Thomas
T1  - Genetic Spectrum of Syndromic and Non-Syndromic Hearing Loss in Pakistani Families
JF  - Genes
N2  - The current molecular genetic diagnostic rates for hereditary hearing loss (HL) vary considerably according to the population background. Pakistan and other countries with high rates of consanguineous marriages have served as a unique resource for studying rare and novel forms of recessive HL. A combined exome sequencing, bioinformatics analysis, and gene mapping approach for 21 consanguineous Pakistani families revealed 13 pathogenic or likely pathogenic variants in the genes GJB2, MYO7A, FGF3, CDC14A, SLITRK6, CDH23, and MYO15A, with an overall resolve rate of 61.9%. GJB2 and MYO7A were the most frequently involved genes in this cohort. All the identified variants were either homozygous or compound heterozygous, with two of them not previously described in the literature (15.4%). Overall, seven missense variants (53.8%), three nonsense variants (23.1%), two frameshift variants (15.4%), and one splice-site variant (7.7%) were observed. Syndromic HL was identified in five (23.8%) of the 21 families studied. This study reflects the extreme genetic heterogeneity observed in HL and expands the spectrum of variants in deafness-associated genes.
KW  - genetic diagnosis
KW  - consanguinity
KW  - genome-wide linkage analysis
KW  - hearing loss
KW  - Pakistan
KW  - exome sequencing
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219293
SN  - 2073-4425
VL  - 11
IS  - 11
ER  -