Estimating the human mutation rate from autozygous segments reveals population differences in human mutational...

Area of Science:

• Genetics
• Population Genetics
• Genomics

Background:

• Estimating human mutation rates is crucial for understanding genetic diversity and disease.
• Previous estimates have varied significantly depending on the methodology.
• High parental relatedness within populations offers a unique approach to study de novo mutations.

Purpose of the Study:

• To estimate the germ-line mutation rate in a multi-generational context within a non-European population.
• To investigate the contribution of post-zygotic mutations to the overall mutation rate.
• To identify population-specific mutational processes.

Main Methods:

• Utilized exome sequencing data from 3222 British-Pakistani individuals with high parental relatedness.
• Analyzed heterozygous mutations within homozygous segments to ascertain de novo mutations.
• Calculated mutation and non-crossover gene conversion rates per base pair per generation.

Main Results:

• Estimated a germ-line mutation rate of 1.45 × 10⁻⁸ per base pair per generation.
• Estimated a non-crossover gene conversion rate of 8.75 × 10⁻⁶ per base pair per generation.
• Observed frequent recurrence of mutations at CpG sites and an increase in C to T mutations in a specific context within the Pakistani population.

Conclusions:

• The estimated mutation rate is at the lower end of previous findings, suggesting limited contribution from post-zygotic mutations.
• Evidence suggests rapid evolution of mutational processes between human populations.
• The study highlights the importance of considering population-specific factors in mutation rate estimation.