ABSTRACT
Objective Mitochondrial transfer RNA for leucine 1(MTTL1)is one of the most important causative genes of oxidative phosphorylation disorders.To understand the clinical,pathological and molecular genetics features of the disordel's caused by MTTL1 mutation.18 patients with a causative mutation in MTTL1 were analyzed.Methods The clinical features,the findings of tlleir biochemistry tests.the neuroimagings,the pathology of biopsied muscles and hereditary characteristics were retrospectively summarized.Results The mutations mt3243A>G and mt3271A>T within MTTL1 gene led to variant syndrome,encephalomyopathies with lactic acidosis and stroke like episodes,diabetes mellitus,progressive external ophthalmoplegia,leish syndrome and complex mitochondrial syndrome were reported.Usually,most patients were sporadic but maternal transmission was the common inherited model.Conclusion The disorders caused by the MTTL1 mutation are hishly phenotypic vailable.There is no association between phenotype and heteroplasmy in muscle.