Abstract: Objective　To investigate the characteristics of clinical manifestation and gene mutation of reversible respiratory chain deficiency in infants with mitochondrial MT-TE gene mutation. Methods　Clinical data of a child diagnosed as reversible infantile respiratory chain deficiency was retrospectively analyzed and related literature was reviewed. Results A male infant, 2 months and 23 days, presented with low weight, short of breath, both lungs can hear snoring and wheezing, hypotonia, and level IV muscle strength. One of his sisters died of severe pneumonia shortly after birth. At the time of admission, blood test showed creatine kinase isoenzyme 123 U/L, creatine kinase 890 U/L, blood lactate 8.9 mmol/L, and pathogen examination were negative. There was no abnormality in the head MRI. After admission, the child continued to have high lactatemia, abnormal muscle enzymes, and difficult breath, and died after giving up treatment. Genetic testing revealed a 14674T>C mutation in the mitochondrial MT-TE gene, which was inherited from his mother. Literature reports found that early clinical manifestations of patients with mitochondrial MT-TE 14674T>C mutations are similar to progressive mitochondrial diseases which is characterized by respiratory muscle weakness, feeding difficulties, delayed motor development milestones, increased muscle enzymes and lactic acid. Replenish energy, maintain internal stability and other treatments could gradually improve clinical symptom around 1 year old. Conclusions　This case is a reversible infantile respiratory chain deficiency caused by a mitochondrial MT-TE mutation. Early manifestations of this disease are similar to those of progressive mitochondrial disease, and the prognosis is good. Early genetic testing can confirm the prognosis and enhance the confidence of treatment.

Key words: reversible;　respiratory chain deficiency;　MT-TE gene mutation:　mitochondrial myopathy