Abstract: Objective To explore the clinical and genetic characteristics of dopa-responsive dystonia (DRD) in infants. Methods The clinical data of DRD in 4 infants admitted from April 2016 to June 2020 were retrospectively analyzed. Results In the 4 children ( 3 boys and 1 girl) the onset age ranged from 2 months to 7 months. The clinical manifestations were developmental retardation or regression, muscle weakness and dystonia. There were no abnormalities in blood biochemistry, blood ammonia and blood lactic acid tests. Electroencephalogram and cranial magnetic resonance imaging (MRI) showed no obvious abnormality. There was no abnormality in routine chromosomal examination, while the compound heterozygous pathogenic variation of TH gene was found. In case 1 , c. 457 C>T was inherited from the father and c.1196C>T was inherited from the mother. In case 2, c.698G>A was inherited from the father and c.1293+5G>C was inherited from the mother. In case 3 , c. 880 G>C was inherited from father and c. 690 C>A was inherited from the mother. In case 4 , c. 739 G>A was inherited from the father and c. 1293 + 5 G>C was inherited from the mother. All of them were reported to be pathogenic variants. Cases 1 , 2 , and 3 were treated with low dose of dopasrazide after diagnosis, and the dose was gradually increased to obtain the best effect. The children were followed up for 1 . 5 ~ 3 years, and the current maximum dose of the drug was 20 ~ 25 mg/(kg · d). All the children recovered basically. At present, the dosage of dosilazine in case 4 was 12 mg/(kg · d), and dystonia was still present when agitated, and the dosage was continued to be increased slowly. Conclusion The symptoms of DRD are not special in infants. Genetic tests should be performed as soon as possible, and the treatment effect of doserazine is good.

Key words: Segawa disease; dopamine; dystonia; TH gene