The Screening Research Of Dopa-responsive Dystonia Gene Mutation In One Chinese Family

Background and Objective: Dopa-responsive dystonia(DRD) is a kind of hereditary movement disorders with dystonic disorder or gait abnormalities as the first symptom. DRD is characterized by pron to childhood-onset dystonia which is associated with tremor, a typical diurnal fluctuation that improving with sleep and worsening during the day, marked and sustained response to relatively low doses of levo-dopa. This potential for therapy emphasizes the importance of diagnosis of DRD families. However, clinical manifestations of DRD vary widely, such as childhood-onset form may present with a dystonia phenotype resembling atypical cerebral palsy, so the early diagnosis of DRD is difficult and many cases are misdiagnosed. Therefore, molecular analyses of DRD families are of crucial importance for clarifying the molecular genetics. DRD is mostly caused by mutations in the GCH-1 gene and more rarely in the TH gene or SPR gene. But some researchers found that some patients did not detect mutations in the three candidate genes, suggesting that there may be new gene mutation causing DRD disease. Due to the rapid development of the HapMap project is completed and the next-generation sequencing technologies, which provided a new method to explore new disease gene of DRD. Methods: This study firstly based on a Chinese family with a clinical diagnosis of DRD was collected, including 2 patients and 2 asymptomatic immediate family members. Using PCR and DNA direct sequencing to screened for mutation in GCH-1, TH, SPR genes. If there is no mutation found, we plan to use whole-genome SNP genotyping scan by Human whole genome-wide SNP array to the DRD gene in this family, which including 6 DRD patients and 4 asymptomatic immediate family members. Results: 1. A total of 2 DRD patients and 2 asymptomatic immediate family members was screened for mutation in GCH-1 gene, TH gene, SPR gene. None of them gene mutation. 2. For the SNP microarray data from DRD pedigree 10 individuals, using bioinformatics methods and screening 552 SNPs that associated with human disease. 3. Alternative visualization and brief analysis of individual raw data with the Genomestudio Software, we filter out 1005 SNPs with low frequency. 4. Finally, we use genetic linkage analysis screening nine candidate genes, then we consider SLC18A1 gene might be the susceptible gene of DRD by sequencing DRD within pedigrees, and identify the exon sequencing data quality with sequencing results, its accuracy up to 96.3%. Conclusions: 1. The GCH1 gene, TH gene, SPR gene are not causative gene of the DRD pedigree. 2. SLC18A1 gene might be the susceptible gene of DRD, but much more experiments must be carried out to prove this.