Abstract: Objective To observe the length heteroplasmy and point heteroplasmy in human mtDNA control region. Methods The peripheral blood, buccal cell, and single hair shaft from 50 individuals and 16 family members, related in their maternallineage were analyzed by direct sequencing, and clones from 20 individuals whose mtDNA sequences have a T-C transition at 16189 nt were sequenced. Results No point heteroplasmy were observed in peripheral blood, buccal cell, single hair shaft from the same individual, neither in maternally related individuals. Length heteroplasmy was observed in those individuals with a homopolymeric tract and the different clones from the same individual has different proportions of length variants, but the hair shafts from the same individual were very similar to the measurements made from blood DNA. no length heteroplasmy was observed between different tissues from the same individual. Conclusion mtDNA sequences have a characteristic of high consistency and genetic stability, mtDNA sequencing is a suitable tool for forensic applications such as individual identification .

Key words: mitochondrial DNA(mtDNA), cloning sequencing, point heteroplasmy, length heteroplasmy