The detection of linkage disequilibrium in molecular sequence data

Area of Science:

• Population genetics
• Molecular evolution
• Bioinformatics

Background:

• Most polymorphic genetic sites exhibit asymmetrical allele frequencies, with rare alleles near fixation.
• Detecting linkage disequilibrium is difficult when rare alleles appear infrequently (e.g., <5 times) due to statistical limitations of tests like Fisher's exact test.

Purpose of the Study:

• To develop a robust statistical method for detecting linkage disequilibrium in population genetic sequence data, even with rare alleles.
• To optimize strategies for maximizing statistical power in linkage disequilibrium studies.

Main Methods:

• Derivation of a novel statistical test for overall linkage disequilibrium based on the sign of observed disequilibria.
• Comparison of the power of increasing sequencing length versus increasing sample size for the same research effort.

Main Results:

• The proposed method effectively utilizes all available data, including sites with rare alleles, overcoming limitations of traditional association tests.
• Increasing the length of determined sequence provides greater statistical power for detecting linkage disequilibrium than increasing the number of sampled genomes for equivalent work.

Conclusions:

• A new, more inclusive method for linkage disequilibrium analysis has been developed, enhancing the study of genetic variation.
• Prioritizing sequencing depth over sample size is a more efficient approach for powerful genetic variation studies.