Clinical exome sequencing in early-onset generalized dystonia and large-scale resequencing follow-up.
Dystonia is clinically and genetically heterogeneous. Despite being a first-line testing tool for heterogeneous inherited disorders, whole-exome sequencing has not yet been evaluated in dystonia diagnostics. We set up a pilot study to address the yield of whole-exome sequencing for early-onset generalized dystonia, a disease subtype enriched for monogenic causation.



Clinical whole-exome sequencing coupled with bioinformatics analysis and detailed phenotyping of mutation carriers was performed on 16 consecutive cases with genetically undefined early-onset generalized dystonia. Candidate pathogenic variants were validated and tested for cosegregation. The whole-exome approach was complemented by analyzing 2 mutated yet unestablished causative genes in another 590 dystonia cases.



Whole-exome sequencing detected clinically relevant mutations of known dystonia-related genes in 6 generalized dystonia cases (37.5%), among whom 3 had novel variants. Reflecting locus heterogeneity, identified unique variants were distributed over 5 genes (GCH1, THAP1, TOR1A, ANO3, ADCY5), of which only 1 (ANO3) was mutated recurrently. Three genes (GCH1, THAP1, TOR1A) were associated with isolated generalized dystonia, whereas 2 (ANO3, ADCY5) gave rise to combined dystonia-myoclonus phenotypes. Follow-up screening of ANO3 and ADCY5 revealed a set of distinct variants of interest, the pathogenicity of which was supported by bioinformatics testing and cosegregation work.



Our study identified whole-exome sequencing as an effective strategy for molecular diagnosis of early-onset generalized dystonia and offers insights into the heterogeneous genetic architecture of this condition. Furthermore, it provides confirmatory evidence for a dystonia-relevant role of ANO3 and ADCY5, both of which likely associate with a broader spectrum of dystonic expressions than previously thought. © 2016 International Parkinson and Movement Disorder Society.
Institut für Neurogenomik, Helmholtz Zentrum München, Munich, Germany.|Klinik und Poliklinik für Neurologie, Klinikum rechts der lsar, Technische Universität München, Munich, Germany.
Michael
M
Zech
Department of Neurology, Medical University Innsbruck, Innsbruck, Austria.
Sylvia
S
Boesch
Klinik und Poliklinik für Neurologie, Klinikum rechts der lsar, Technische Universität München, Munich, Germany.
Angela
A
Jochim
Institut für Neurogenomik, Helmholtz Zentrum München, Munich, Germany.
Sandrina
S
Weber
Klinik und Poliklinik für Neurologie, Klinikum rechts der lsar, Technische Universität München, Munich, Germany.
Tobias
T
Meindl
Institut für Neurogenomik, Helmholtz Zentrum München, Munich, Germany.
Barbara
B
Schormair
Institut für Humangenetik, Helmholtz Zentrum München, Munich, Germany.
Thomas
T
Wieland
Neuromuscular Omnicentre Sud (NEMO SUD), Fondazione Aurora Onlus, Messina, Italy.
Christian
C
Lunetta
Neuromuscular Omnicentre (NEMO), Fondazione Serena Onlus, Milan, Italy.|Department of Biochemical Sciences for Health, University of Milan, Milan, Italy.
Valeria
V
Sansone
Schön Klinik München Schwabing, Munich, Germany.
Michael
M
Messner
Department of Neurology, Medical University Innsbruck, Innsbruck, Austria.|Vivantes Klinikum Spandau, Berlin, Germany.
Joerg
J
Mueller
Klinik und Poliklinik für Neurologie, Klinikum rechts der lsar, Technische Universität München, Munich, Germany.|Schön Klinik München Schwabing, Munich, Germany.
Andres
A
Ceballos-Baumann
Institut für Humangenetik, Helmholtz Zentrum München, Munich, Germany.|Institut für Humangenetik, Technische Universität München, Munich, Germany.
Tim M
TM
Strom
Institute of Clinical Biochemistry, Catholic University, Rome, Italy.|Center for the Study of Rare Hereditary Diseases, Niguarda Ca' Granda Metropolitan Hospital, Milan, Italy.
Roberto
R
Colombo
Department of Neurology, Medical University Innsbruck, Innsbruck, Austria.
Werner
W
Poewe
Klinik und Poliklinik für Neurologie, Klinikum rechts der lsar, Technische Universität München, Munich, Germany.
Bernhard
B
Haslinger
Institut für Neurogenomik, Helmholtz Zentrum München, Munich, Germany.|Klinik und Poliklinik für Neurologie, Klinikum rechts der lsar, Technische Universität München, Munich, Germany.|Munich Cluster for Systems Neurology, SyNergy, Munich, Germany.|Institute of Human Genetics, Klinikum rechts der Isar, Technical University Munich, Munich, Germany.
Juliane
J
Winkelmann
D000262:Adenylyl Cyclases / Q000235:genetics; D000328:Adult; D000075368:Anoctamins; D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D018118:Chloride Channels / Q000235:genetics; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics; D004421:Dystonia / Q000235:genetics*; D059472:Exome / Q000235:genetics*; D005192:Family Health; D005260:Female; D005500:Follow-Up Studies; D006136:GTP Cyclohydrolase / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000235:genetics; D009154:Mutation / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D055815:Young Adult
C577591:ANO3 protein, human; D000075368:Anoctamins; D051017:Apoptosis Regulatory Proteins; D018118:Chloride Channels; D004268:DNA-Binding Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins; C474080:THAP1 protein, human; C108175:TOR1A protein, human; D006136:GTP Cyclohydrolase; D000262:Adenylyl Cyclases; C419510:adenylyl cyclase type V
ADCY5; ANO3; diagnostics; dystonia; exome