Linkage disequilibrium

Linkage Disequilibrium is a term used in the field of genetics to describe a situation where the frequency of association of alleles at two or more loci is not the same as would be expected from a random formation of haplotypes from alleles based on their frequencies. This phenomenon is a crucial factor in the discovery and analysis of genetic association.

Overview

Linkage Disequilibrium (LD) is a non-random association of alleles at different loci. It is a measure of the degree to which the allele at one genetic locus is associated with the allele at another locus. The presence of LD can significantly impact the frequency and distribution of multi-locus genotypes in a population.

Causes

The primary causes of Linkage Disequilibrium include genetic linkage, genetic drift, population bottleneck, founder effect, and natural selection.

Measurement

There are several ways to measure Linkage Disequilibrium, including D', r^2, and the chi-square test. Each method has its advantages and disadvantages, and the choice of method depends on the specific circumstances.

Implications

Linkage Disequilibrium has significant implications in the field of genetic epidemiology, particularly in the mapping of complex genetic diseases. It is also a crucial factor in the design and interpretation of genome-wide association studies (GWAS).

See Also

• Genetic linkage
• Genetic association
• Genome-wide association study
• Population genetics

Linkage disequilibrium

• File:Linkage Disequilibrium Heatmap.png