AB036. Analysis of human mitochondrial genome mutations of Vietnamese patients tentatively diagnosed with encephalomyopathy

Abstract: Human mitochondrial genome consists of 16,569 bp, and replicates independently from the nuclear genome. Mutations in mitochondrial genome are usually causative factors of various metabolic disorders, especially those of encephalomyopathy. DNA analysis is the most reliable method for detection of mitochondrial genome mutations, and accordingly an excellent diagnostic tool for mitochondrial mutation-related diseases. In this study, 19 different mitochondrial genome mutations including A3243G, A3251G, T3271C and T3291C (MELAS); A8344G, T8356C and G8363A (MERRF); G3460A, G11778A and T14484C (LHON); T8993G/C and T9176G (Leigh); A1555G (deafness) and A4225G, G4298A, T10010C, T14727C, T14728C, T14709C (encephalomyopathy in general) were analyzed using PCR-RFLP in combination with DNA sequencing. In addition, a real-time PCR method using locked nucleic acid (LNA) Taqman probe was set up for heteroplasmy determination. Screening of 283 tentatively diagnosed encephalomyopathy patients revealed 7 cases of A3243G, 1 case of G11778A, 1 case of A1555G, 1 case of A4225G, 1 case G4298A, and 1 case of 6 bp (ACTCCT/CTCCTA) deletion. Using the LNA Taqman probe real-time PCR, the heteroplasmy of some point mutations was determined and the results support a potential relationship between heteroplasmy level and severity of the disease.

Keywords: Mitochondrial genome mutations; encephalomyopathy; PCR-RFLP; real-time PCR; heteroplasmy