Understanding Linkage Disequilibrium: Implications for Genetic Studies and Disease Mapping

Linkage Disequilibrium

LD is the non random association of alleles at 2 or more loci in a general population. When alleles are in LD, haplotypes do not occur at the expected frequencies.

Linkage disequilibrium refers to a non-random association of two or more alleles at different loci in a population. It occurs when the frequency of the alleles at one locus is not independent of the frequency of the alleles at another locus.

In other words, if two or more alleles are found together more often than would be expected by chance, they are said to be in linkage disequilibrium. Linkage disequilibrium can arise because of several factors, including genetic drift, natural selection, migration, mutation, and recombination.

Linkage disequilibrium has important implications for genetic studies. It can be used to identify disease-causing genes or to map genetic loci associated with complex traits. For example, if a particular genetic variant is strongly associated with a disease, researchers can look for other variants in the same linkage disequilibrium block that might be causally related to the disease.

It is also important to be aware that linkage disequilibrium can create false positive associations between genetic variants and traits. Therefore, statistical methods such as permutation tests or adjusting for multiple testing are commonly employed to control for false positives and correct for linkage disequilibrium in genetic association studies.

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