A method to detect recombination between a genetic marker and the QTL that it marks

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Breeding Programs

Background:

• Individual genetic markers are often used as causative mutations in marker-assisted selection (MAS).
• Marker effects can decrease over time due to epistasis or recombination disrupting linkage disequilibrium (LD).
• The breakdown of LD between a marker and a causative quantitative trait locus (QTL) is a key challenge in MAS.

Purpose of the Study:

• To present a method for detecting the breakdown of linkage disequilibrium between a genetic marker and a causative QTL.
• To provide breeders with a tool to assess the reliability of single markers in selection programs.
• To inform strategies for maintaining effective marker-assisted selection.

Main Methods:

• The method calculates the probability of a recombinant haplotype for each gamete within a pedigree.
• It utilizes pedigree, phenotype, and single-marker genotype data.
• Handles missing marker genotypes, though with reduced statistical power.

Main Results:

• The method can identify scenarios where recombination is diminishing the effect of a single marker.
• Effectiveness is highest for biallelic markers with strong underlying QTL effects.
• Identifies individuals that may need to be removed from breeding programs to maintain marker utility.

Conclusions:

• Detecting LD breakdown is crucial for the long-term success of marker-assisted selection.
• Breeders can use this method to manage genetic markers and potentially select new markers or haplotypes.
• Strategies include eliminating individuals or finding new linked markers to restore high LD with causative QTL.