Mutation patterns of mtDNA: empirical inferences for the coding region

Area of Science:

• Genetics
• Evolutionary Biology
• Population Genetics

Background:

• Human mitochondrial DNA (mtDNA) is crucial for population and evolutionary genetics.
• Accurate estimation of human mtDNA evolutionary rate is vital across research fields.
• Previous estimations of mtDNA coding region mutation rates showed discrepancies between phylogenetic and empirical methods.

Purpose of the Study:

• To provide empirical estimations of the mtDNA coding region mutation rate.
• To analyze a portion of the mtDNA coding region (tRNALeu, ND1, tRNAIle genes).
• To better understand the mtDNA evolutionary process by analyzing extended families from the Azores Islands.

Main Methods:

• Analysis of mtDNA coding region genes (tRNALeu, ND1, tRNAIle) in extended families.
• Detection and characterization of heteroplasmy (new point mutations, insertions, deletions).
• Empirical estimation of mutation rate considering sex, heteroplasmy fixation probability, and selection.

Main Results:

• Heteroplasmy detected in 6.5% of families, resulting from three new point mutations.
• No insertions or deletions were identified in the studied mtDNA regions.
• Empirical mtDNA coding region mutation rate estimation aligns with phylogenetic approaches when accounting for specific factors.

Conclusions:

• Discrepancies between evolutionary and empirical mtDNA coding region mutation rates can be resolved.
• Correction for factors such as sex, heteroplasmy fixation, and selection reconciles observed mutation rates.
• The study provides a more accurate understanding of the human mtDNA evolutionary process.