Objective: This study was undertaken to assess the phenotypic and genotypic spectrum of children with LS in China, and identify predictors of survival.

Methods: The clinical data of gene confirmed cases were retrospectively summarized and analyzed. All patients were followed up. Oxygen consumption rate of skin fibroblasts was measured in one patient.

Results: 80 cases (48 males and 32 females) were enrolled into the study.

m.8993T>C/G and SURF1 were the most common genetic variants in mtDNA and nDNA separately. The median age of onset was 17 months. The common symptom were developmental retardation, motor disorders, abnormal ocular findings, developmental regression, seizers, encephalopathy, and dyspnea. The result of oxygen consumption rate showed the basal OCR and MRR% were significantly lower than control. All patients were involved in brain stem and(or) basal ganglia. MRI developed overtime in 24 patients, 8 remained steady, 5 had evolution of the lesions, and 3 demonstrated regression of lesions. 47 patients were alive, 21 were died and 12 were lost to follow-up. Age at onset below 16 months and dyspnea were predictors of poorer survival.

Conclusion: Clinical symptoms were overlapped, and single system involvement was rare. All cases with LS showed bilateral brain stem and/or basal ganglia injuries in MRI. Medulla, thalamus, cerebellum, brain white matter involvement and brain atropy were easy to be seen. MRI changes were consistent with prognosis. Measurement of OCR of fibroblasts skin cell helped diagnosis. Age at onset below 16 months and dyspnea were predictors of poorer survival.