Abstract: Objective To investigate the clinical manifestations and gene analysis of Joubert syndrome.Methods The clinical data and gene results of a child with Joubert syndrome caused by TCTN3 gene mutation were analyzed in the Third Affiliated Hospital of Jiamusi University.Results The patient was 5 months and 13 days old.The Color Doppler ultrasound and abdominal fetal MRI during pregnancy showed that fetal cerebellar vermis and brain stem were abnormal.The main clinical manifestations of the child on visiting the hospital were paroxysmal tachypnea,hypotonia and delayed development.Magnetic resonance imaging of the skull showed "molar sign" and "bat wing"-shaped fourth ventricle.The whole exon sequencing showed that there was heterozygous variation c.776dupT,c 737-2A>T of TCTN3 gene,respectively from parents,and it was definitely diagnosed as Joubert syndrome type 18.Joubert syndrome caused by TCTN3 gene mutation was first reported in China,among which c 737-2A>T mutation had not been reported at home or abroad.After 3 months of rehabilitation treatment,the frequency of shortness of breath decreased,the follow-up of sight and hearing improved significantly,and the motor ability and social adaptability improved significantly.Conclusion TCTN3 gene mutation is found in patients with Joubert syndrome that has not been reported in China.The patients with Joubert syndrome should take active rehabilitation treatment,the functions of the eyes,kidneys,liver and other organs should be evaluated regularly,and the patients should take long-term comprehensive rehabilitation treatment and follow-up observation.

Key words: Joubert syndrome, TCTN3；Molar sign；Cerebellar and brainstem developmental defect