The THAP domain is a C2CH module with zinc-dependent sequence-specific DNA-binding activity []. Several THAP domain-containing proteins have been described. Human THAP1 is a transcription regulator that regulates endothelial cell proliferation and G1/S cell-cycle progression []. It specifically binds the 5'-[AT]NTNN[GT]GGCA[AGT]-3' core DNA sequence and acts by modulating expression of pRB-E2F cell-cycle target genes, including RRM1. It is a component of a THAP1/THAP3-HCFC1-OGT complex that is required for the regulation of the transcriptional activity of RRM1. It may also have pro-apoptopic activity by potentiating both serum-withdrawal and TNF-induced apoptosis [, , ]. Defects in THAP1 are the cause of dystonia type 6 (DYT6). DYT6 is a primary torsion dystonia. Dystonia is defined by the presence of sustained involuntary muscle contractions, often leading to abnormal postures. Dystonia type 6 is characterised by onset in early adulthood, cranial or cervical involvement in about half of the cases, and frequent progression to involve multiple body regions [, , , ].
