Abstract: 　Objectives　To investigate the clinical and PMPCB genetic mutation features of multiple mitochondrial dysfunctions syndrome 6 (MMDS6). Methods　The clinical data of a case with MMDS6 were retrospectively analyzed and related literature was reviewed. Results　A 5-months-old boy presented with poor weight gain and feeding difficulty, delayed motor development and hypotonia, with lactic acidosis and heart failure. Echocardiography showed pulmonary hypertension. A homozygous nucleotide variation of c.524G>A in PMPCB gene was found through whole-exome and mitochondrial genome sequencing analysis, which has not been reported before in literature and both parents were heterozygotes. Conclusion　The homozygous nucleotide variation c.524G>A in PMPCB gene was pathogenic variants for MMDS6. Next-generation sequencing may provide diagnosis for the disease.

Key words: PMPCB gene;　multiple mitochondrial dysfunction syndrome;　lactic acidosis;　psychomotor retardation