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Allele frequency. Allele frequency, or gene frequency, is the relative frequency of an allele (variant of a gene) at a particular locus in a population, expressed as a fraction or percentage. [1] Specifically, it is the fraction of all chromosomes in the population that carry that allele over the total population or sample size.
Frequency-dependent selection is an evolutionary process by which the fitness of a phenotype or genotype depends on the phenotype or genotype composition of a given population. In positive frequency-dependent selection, the fitness of a phenotype or genotype increases as it becomes more common. In negative frequency-dependent selection, the ...
In population genetics, linkage disequilibrium (LD) is a measure of non-random association between segments of DNA at different positions on the chromosome in a given population based on a comparison between the frequency at which two alleles are detected together at the same loci versus the frequencies at which each allele is simply detected (alone or with the second allele) at that same loci.
Genotype frequency in a population is the number of individuals with a given genotype divided by the total number of individuals in the population. [2] In population genetics, the genotype frequency is the frequency or proportion (i.e., 0 < f < 1) of genotypes in a population. Although allele and genotype frequencies are related, it is ...
2. Find MAF/MinorAlleleCount link. MAF/MinorAlleleCount: C=0.1506/754 (1000 Genomes, where number of genomes sampled = N = 2504); [ 4 ] where C is the minor allele for that particular locus ; 0.1506 is the frequency of the C allele (MAF), i.e. 15% within the 1000 Genomes database; and 754 is the number of times this SNP has been observed in the ...
A highly indicative test of changes in allele frequencies is the QTL sign test, and other tests include the Ka/Ks ratio test and the relative rate test. The QTL sign test compares the number of antagonistic QTL to a neutral model, and allows for testing of directional selection against genetic drift. [11]
Genetic distance. Genetic distance is a measure of the genetic divergence between species or between populations within a species, whether the distance measures time from common ancestor or degree of differentiation. [ 2 ] Populations with many similar alleles have small genetic distances.
In this case the odds ratio for allele T is A:B (meaning 'A to B', in standard odds terminology) divided by X:Y, which in mathematical notation is simply (A/B)/(X/Y). When the allele frequency in the case group is much higher than in the control group, the odds ratio is higher than 1, and vice versa for lower allele frequency.