Journal of Forensic Medicine ›› 2026, Vol. 42 ›› Issue (4): 310-317.DOI: 10.12116/j.issn.1004-5619.2024.540401

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Analysis of Genetic Characteristics of Mitochondrial DNA Genetic Variation in Four⁃Generation Maternal Lineages

Miaoqiang Lun1(), Xingyi Yang2, Quyi Xu2, Xiaolong Han2, Ling Chen1, Mengge Wang3(), Chao Liu1,4()   

  1. 1.School of Forensic Medicine, Southern Medical University, Guangzhou 510515, China
    2.Guangzhou Institute of Criminal Science and Technology, Guangzhou 510080, China
    3.Institute of Rare Diseases, West China Hospital, Sichuan University, Chengdu 610041, China
    4.Anti-drug Technology Center of Guangdong Province, Guangzhou 510230, China
  • Received:2024-04-03 Online:2026-10-28 Published:2026-08-25
  • Contact: Mengge Wang, Chao Liu

Abstract:

Objective To investigate the genetic characteristics of homoplasmic and heteroplasmic mitochondrial DNA (mtDNA) variations in four-generation maternal lineages. Methods Buccal swabs were collected from 23 individuals belonging to 4 four-generation maternal lineages. DNA was extracted, and mtDNA whole genome libraries were constructed. Sequencing was performed using the Ion S5 XL sequencing system, followed by sequence alignment and variation analysis. Results Following quality control and analysis of obtained mtDNA whole genome sequencing data, the sequencing coverage reached 99.73%, and the average sequencing depth was 3 458×. A total of 939 genetic variations were observed, including 883 point mutations, 36 insertion/deletion variations, and 20 heteroplasmic variations. No differentiated homoplasmic point mutations were found in the mtDNA sequences of individuals from the same maternal lineage, whereas inconsistent point heteroplasmies (PHPs) were detected. Conclusion Mitochondrial PHP variations can change during inheritance, and there is a risk of using PHP differences as an exclusion criterion for determining whether individuals come from the same maternal lineage. When comparing mtDNA sequences, if the same PHP is observed in two samples with identical haplotypes and its major and minor alleles are consistent, it can be considered as enhanced evidence to determine that the two samples come from the same maternal lineage.

Key words: forensic genetics, mitochondrial DNA (mtDNA), whole genome sequencing, heteroplasmic variation, matrilineal relationship identification, next-generation sequencing

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