Molecular Genetic Study Of Dopa-responsive Dystnia

ObjectiveThe study aims to analyze clinical features of dopa-responsive dystoniaand detect the mutations in related genes, and to understand critical genemutation responsible for dopa-responsive dystonia in Chinese population andprovide the basis for early diagnosis.MethodsWe observed clinical manifestations of six cases of sporadic DRD patientsand one family with two affected members and carried out auxiliary checks tothem. Meanwhile venous blood was collect from the six patients and fourmembers in the family to extract DNA. Six pairs of primers were designed forGCH1, a common pathogenic gene in DRD, and14pairs of primers for TH, arare gene. PCRs were performed using these primers, and the PCR resultswere sequenced after agarose gel electrophoresis, electrophoresis, plasticrecycling and purification to detect mutated sites.Results1．A new heterozygous deletion mutation in exon1(26bases between421-446were deleted) of GCH1gene was found in one sporadic case; A newheterozygous mutation in exon six of GCH1(125alkali base changed from T into C) was detected in another sporadic case, leading to the251stterminationcode replaced by Arg. GCH1mutation was not found in other four sporadiccases. In the family with two patients, two patients and their father were foundwith a new mutation (444thbase changed from C into A) in exon1of GCH1gene, resulting in that the95thPro were replaced by Thr; No abnormality wasfound to their mother; The previous three mutations have not been reportedbefore.2．A G-A mutation at152base in exon3of TH gene was found in the fourmembers of the family, leading to the108thVal changed into Met (Val108Met)which has been reported; Two new mutations were found in one sporadic case:G-A at35thbase in exon8and C-T at80thbase in exon12of TH gene, resultingin a Ala271Thr and Ser422Phe, respectively. These two new mutations werereported at the first time.Conclusions1．421-446del26mutation and C-A mutation at the444thbase in exon1, T-Cmutation at125thbase in exon6, and C-T mutation at80thbase in exon12haveinfluences on protein function with pathogenicity, which maybe the moleculargenetic etiology of DRD.2．G-A mutation at152ndbase in exon3and G-A mutation at35thbase inexon8of TH gene do not affect protein function, and have no pathogenicity,which can be categorized into single nucleotide polymorphism.3．We found that the clinical features caused these types of mutations wereconsistent with these of other known types of gene mutations.