Case Report Sporadic type 2 diabetes mellitus, atherosclerosis and essential hypertension associated with the mitochondrial tRNALys A8343G mutation

We reported here the molecular characterization of a mutation: A8343G in the TψC loop of mitochondrial tRNALys gene of a 57-year-old woman who manifested type 2 diabetes mellitus, arteriosclerosis and essential hypertension. No other family members were affected, suggested that our patient was a sporadic case. Sequence analysis for the entire mitochondrial genome showed the presence of a homoplasmic A8343G mutation and a set of polymorphisms belonging to human mitochondrial haplogroup B4b1c. The adenine (A) at position 8343 was very important in the structural formation and stabilization of functional tRNAs, which was evolutionary conserved in mitochondria of various organisms and also contributed to the high fidelity of the TψC loop of tRNA. Thus, the structural alternation of tRNA by the A8343G mutation may lead to a failure in tRNA metabolism and impair mitochondrial protein synthesis. Therefore, the tRNALys A8343G mutation may have a potential modifier role in type 2 diabetes mellitus, arteriosclerosis and essential hypertension. Our finding broadened the phenotypic and molecular spectrum of mitochondrial tRNALys associated disorders.