To identify potential mutation of the GCH1 gene in a Chinese family affected with dopa-responsive dystonia.Genomic DNA of patients was extracted from peripheral blood samples. The 6 exons of the GCH1 gene and at least 100 bp of flanking intronic sequences were amplified with PCR. Potential mutations were screened by direct sequencing. Identified mutation was verified with denaturing high performance liquid chromatography (DHPLC) in 100 healthy controls.All patients were found to be heterozygous for a novel c.597delT (p.Ala200LeufsX5) deletion in the exon 5 of the GCH1 gene. The deletion of T has resulted in formation of a shorter (203 amino acids) truncated non-functional guanosine triphosphate cyclohydrolase I. The same mutation was not found in the 100 controls.A novel GCH1 gene frameshifing mutation probably underlies the dopa-responsive dystonia in this Chinese family.