Using dominance relationship coefficients based on linkage disequilibrium and linkage with a general complex pedigree...

Area of Science:

• Genetics
• Quantitative Genetics
• Bioinformatics

Background:

• Dominance, or intralocus allelic interactions, significantly influences quantitative trait variation.
• Previous quantitative trait loci (QTL) mapping studies have limitedly addressed dominance in outbred animal and human populations due to challenges in estimating dominance relationships without full sibs and with incomplete genotypes.
• Estimating dominance relationship coefficients is often infeasible in natural populations with general pedigrees.

Purpose of the Study:

• To develop a novel method for QTL mapping that incorporates dominance effects in outbred populations.
• To enable the estimation of dominance relationships between unrelated founders using population-wide linkage disequilibrium (LD).
• To overcome the limitations of traditional QTL mapping methods that require full sibs or complete genotypes.

Main Methods:

• Estimation of identity-by-descent (IBD) coefficients based on population-wide linkage disequilibrium (LD).
• Utilizing a Markov chain Monte Carlo (MCMC) method for efficient estimation of IBD and dominance relationship matrices (D(RM)) with incomplete genotypes and complex pedigrees.
• Simulation studies to evaluate the performance of the proposed method.

Main Results:

• The proposed method successfully tracks dominance relationships between unrelated founders.
• The use of dominance relationship matrices (D(RM)) significantly increases the likelihood ratio at the true QTL position.
• Improved mapping accuracy and power were observed for complete dominance, overdominance, and recessive inheritance modes in simulations with 200 individuals.

Conclusions:

• Dominance effects can be effectively incorporated into QTL mapping in outbred populations without the need for full sibs.
• The developed method, utilizing IBD estimation via LD and MCMC, provides a robust framework for analyzing dominance in complex pedigrees.
• This advancement enhances the potential for identifying genetic underpinnings of complex traits in diverse populations.