[Heteroplasmy: a common phenomenon of mitochondrial genome mutations in human tumor tissues]

To explore the status of heteroplasmy and homoplasmy of Mitochondrial DNA somatic mutations in different tumors. DNA from 149 tumors and corresponding normal tissues were extracted and entire mitochondrial genome was amplified using 32 pairs of overlapping primers. The somatic mutations were screened by temporal temperature gradient gel electrophoresis and their heteroplasmic statute were identified by sequencing. The results showed that the incidence rate of heteroplasmy of mitochondrial DNA somatic mutations varies in different tumors. There is a high rate of heteroplasmic mutation in oral cancer (65%) and esophageal cancer (64%), followed by breast cancer (45%). The frequency of four transfer types is Hm (homoplasmy)-->Hm (heteroplasmy) > Hm-->Ht > Ht-->Hm > Ht-->Ht. The main transfer forms of transition and transversion mutations are Hm-->Hm and Hm-->Ht respectively. Heteroplasmy is a common phenomenon in mitochondrial DNA somatic mutations of human tumors.