Phenotype in 6 patients with mitochondrial DNA G13513A mutation

：Objective To report 6Chinese patients with mitochondrial encephalomyopathy caused by mitochondrialDNA(mtDNA)G13513A mutation and discuss the mitochondrial phenotype associated with thismutation based on the data of our patient series as well as the reports by others.MethodsDirect sequencing of polymerase chain reaction(PCR)products or PCR-RFLP analysis Wasperformed to screen mtDNA G13513A mutation in 35 cases with mitoehondrialencephalomyopathy.who carried no mtDNA common mutations(1arge 8eale deletion,A3243G,T3271C,A8344G,or T8993G/C).The clinical features,MRI changes were retrospectively collected andanalyzed.Published studies of all patients with mtDNA G13513A mutation were alsoreviewed.Results Six patients were identified carrying mtDNA G13513A mutation.All patientspresented stroke-like episodes with hemianopsia.hemiparesis or hemiparesthesia.Three adultpatients presented clinical and radiological features of adult-onset mitochondrialmyopathy,encephalopathy,lactic acidosis,and stroke-like episodes(MELAS),includingstroke-like episodes,epilepsy,headache,short stature,sensorineural deafness,multifocallesions on parietal,occipital and temporal lobes on cranial MRI scans.Three iuvenile.onsetpatients presented the clinical and brain MRI features of MELAS-Leigh syndrome(LS)overlapsyndrome.In addition to the stroke-like episodes,they also showed brain stem lesions withdysarthria,ataxia,and ophthalmopJegia. Brain MRI revealed asymmetrical lesions in thecortex of the oecipital and temporal lobes,as well as symmetrical lesions in the bilateralbasal ganglia and brainstem.Muslce biopsy showed ragged redfibem in 5 patients.Theinfant-onset LS or Leigh-like syndrome with mtDNA G135 13A was described in the Englishliterature.Conclusions mtDNA G13513A mutation is a common pathogenic mutmion formitochondrial encephalomyopathy,which can result in Leigh syndrome,MELAS-LS overlapsyndrome and adult MELAS.The onset of various phenotypes is relatively age-dependent.