Autosomal dominant progressive external ophthalmoplegia (adPEO) is a mitochondrial disorder caused by mutations in nuclear genes. Here we report the clinical and genetic features of adPEO in a Chinese family. All patients had gradual onset of ptosis, with or without ophthalmoplegia, around age 30. Thirteen patients had limb weakness around age 40. Eight patients developed dysphagia around age 50. Four patients died of cardiac abnormalities around age 60. Muscle biopsy of the proband indicated mitochondrial myopathy characterized by ragged-red fibers, cytochrome c oxidase-negative fibers, and multiple deletions of mitochondrial DNA. A heterozygous missense mutation of c.1342A>G in the C10orf2 gene resulting in the p.448N>D mutation in the protein was found in the proband and four other affected family members. In summary, we identified an adPEO family with a novel C10orf2 gene mutation that manifested an age-dependent phenotype. It suggests that greater attention must be paid to cardiac abnormalities in the late stages of this disease. Muscle Nerve 41: 92-99, 2010