DYT6 dystonia: review of the literature and creation of the UMD Locus-Specific Database (LSDB) for mutations in the THAP1 gene.

By family-based screening, first Fuchs and then many other authors showed that mutations in THAP1 (THAP [thanatos-associated protein] domain-containing, apoptosis-associated protein 1) account for a substantial proportion of familial, early-onset, nonfocal, primary dystonia cases (DYT6 dystonia). THAP1 is the first transcriptional factor involved in primary dystonia and the hypothesis of a transcriptional deregulation, which was primarily proposed for the X-linked dystonia-parkinsonism (DYT3 dystonia), provided thus a new way to investigate the possible mechanism underlying the development of dystonic movements. Currently, 56 families present with a THAP1 mutation; however, no genotype/phenotype relationship has been found. Therefore, we carried out a systematic review of the literature on the THAP1 gene to colligate all reported patients with a specific THAP1 mutation and the associated clinical signs in order to describe the broad phenotypic continuum of this disorder. To facilitate the comparison of the identified mutations, we created a Locus-Specific Database (UMD-THAP1 LSDB) available at https://www.umd.be/THAP1/. Currently, the database lists 56 probands and 43 relatives with the associated clinical phenotype when available. The identification of a larger number of THAP1 mutations and collection of high-quality clinical information for each described mutation through international collaborative effort will help investigating the structure-function and genotype-phenotype correlations in DYT6 dystonia.