ABSTRACT
Mutations in THAP1 have been associated with dystonia 6 (DYT6). THAP1 encodes a transcription factor that represses the expression of DYT1. To further evaluate the mutational spectrum of THAP1 and its associated phenotype, we sequenced THAP1 in 567 patients with focal (n = 461), segmental (n = 68), or generalized dystonia (n = 38). We identified 10 novel variants, including six missense substitutions within the DNA-binding Thanatos-associated protein domain (Arg13His, Lys16Glu, His23Pro, Lys24Glu, Pro26Leu, Ile80Val), a 1bp-deletion downstream of the nuclear localization signal (Asp191Thrfs*9), and three alterations in the untranslated regions. The effect of the missense variants was assessed using prediction tools and luciferase reporter gene assays. This indicated the Ile80Val substitution as a benign variant. The subcellular localization of Asp191Thrfs*9 suggests a disturbed nuclear import for this mutation. Thus, we consider six of the 10 novel variants as pathogenic mutations accounting for a mutation frequency of 1.1%. Mutation carriers presented mainly with early onset dystonia (<12 years in five of six patients). Symptoms started in an arm or neck and spread to become generalized in three patients or segmental in two patients. Speech was affected in four mutation carriers. In conclusion, THAP1 mutations are rare in unselected dystonia patients and functional analysis is necessary to distinguish between benign variants and pathogenic mutations.
Subject(s)
Apoptosis Regulatory Proteins/genetics , Apoptosis Regulatory Proteins/metabolism , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Mutation , Nuclear Proteins/genetics , Nuclear Proteins/metabolism , Adolescent , Adult , Age of Onset , Aged , Child , Child, Preschool , Dystonia/epidemiology , Dystonia/genetics , Dystonia/metabolism , Female , Gene Frequency , Genetic Association Studies , Genotype , Humans , Male , Middle Aged , Polymorphism, Genetic , Protein Transport , Young AdultSubject(s)
Apoptosis Regulatory Proteins/genetics , DNA-Binding Proteins/genetics , Mutation/genetics , Nuclear Localization Signals/metabolism , Nuclear Proteins/genetics , Carcinoma/pathology , Cell Line, Tumor , Green Fluorescent Proteins/genetics , Humans , Microscopy, Confocal , Mutagenesis/physiology , Subcellular Fractions/metabolism , Transfection/methodsABSTRACT
Mutations in THAP1 have been associated with dystonia 6. THAP1 encodes a transcription factor with mostly unknown targets. We tested the hypothesis that THAP1 regulates the expression of DYT1 (TOR1A), another dystonia-causing gene. After characterization of the TOR1A promoter, we demonstrate that THAP1 binds to the core promoter of TOR1A. Further, we report that wild type THAP1 represses the expression of TOR1A, whereas dystonia 6-associated mutant THAP1 results in decreased repression of TOR1A. Our data demonstrate that THAP1 regulates the transcription of TOR1A, suggesting transcriptional dysregulation as a cause of dystonia.
