Mitonuclear linkage disequilibrium in human populations

Area of Science:

• Genetics
• Evolutionary Biology
• Human Genomics

Background:

• Disrupting co-adapted mitochondrial and nuclear genotypes in model systems can cause severe health issues.
• The significance of these mitonuclear associations in humans is not well understood, despite extensive human population genetics research.
• Statistical associations between nuclear and mitochondrial alleles in humans remain largely uninvestigated.

Purpose of the Study:

• To investigate historical selection signatures maintaining mitonuclear associations in the human genome.
• To specifically examine associations involving nuclear genes encoding mitochondrial-localized proteins (N-mt genes).

Main Methods:

• Analysis of published human population genomic data.
• Testing for signatures of historical selection on mitonuclear linkage disequilibrium (LD).

Main Results:

• Significant mitonuclear LD was detected across the human genome, but associations were generally weak.
• Weak LD is consistent with low population genetic structure in humans.
• N-mt genes showed no statistically significant difference from background levels of mitonuclear LD, indicating no preferential selection at a species-wide level.

Conclusions:

• Mitonuclear associations in humans are generally weak and not preferentially maintained by selection, particularly for N-mt genes.
• Findings suggest that species-specific factors influence the importance of mitonuclear co-adaptation.
• The results provide context for discussions on mitochondrial replacement therapy.