Tissue-specific mitochondrial heteroplasmy at position 16,093 within the same individual

Area of Science:

• Genomics
• Molecular Biology
• Human Genetics

Background:

• Human mitochondrial DNA (mtDNA) research has advanced with massively parallel sequencing (MPS), enabling detailed genomic analysis and molecular diagnostics.
• MPS allows simultaneous analysis of coding and control regions, parallel study of numerous samples, and detection of minor heteroplasmic changes.

Purpose of the Study:

• To investigate the variability and distribution of heteroplasmy in human mitochondrial DNA across different tissues.
• To explore the ontogenetic origins of somatic mitochondrial heteroplasmy.

Main Methods:

• Utilized massively parallel sequencing (MPS) to analyze mitochondrial DNA (mtDNA).
• Enriched mtDNA using two overlapping long-range PCR amplicons.
• Analyzed 16 different tissues from three adult males using Illumina paired-end sequencing.

Main Results:

• Significant variability in point mutation heteroplasmy (m.16093T > C) was observed across tissues in one individual, ranging from 5.1% in red bone marrow to 62.0% in bladder.
• Red and yellow bone marrow samples clustered together, while arteries and aortas formed a separate group based on heteroplasmy levels.
• These findings suggest an ontogenetic explanation for the formation of somatic mitochondrial heteroplasmy.

Conclusions:

• Multi-tissue screening using MPS yields significant insights even with a small sample size.
• The frequency, distribution, and potential role of mtDNA heteroplasmy in complex diseases and phenotypes may be underestimated.