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Related to Heterozygosity: Loss of heterozygosity



the state, inherent in every hybrid organism, in which homologous chromosomes carry different forms (alleles) of a given gene or differ in the arrangement of genes (structural heterozygosity).

The term “heterozygosity” was first introduced by the English geneticist W. Bateson in 1902. Heterozygosity is the result of the union of gametes of different genetic or structural makeup. Structural heterozygosity arises with the chromosomal rearrangement of one of the homologous chromosomes; it may be detected in meiosis or in mitosis. Heterozygosity is revealed by crossing a hybrid with its homozygous-recessive parental form. Heterozygosity, as a rule, is a consequence of the sexual process, but it can arise as a result of mutation (for example, in the homozygote AA, where one of the alleles has mutated: A→A’). The effect of harmful or lethal recessive alleles is suppressed in a heterozygote by the presence of the corresponding dominant allele and becomes apparent only with the transfer of the allele to a homozygous situation. Heterozygosity is widespread in natural populations and is apparently one of the reasons for hybrid vigor (heterosis). The masking action of the dominant alleles in heterozygosity allows the preservation and diffusion through a population of harmful recessive alleles, which should be unmasked in the course of breeding and selection as well as in making medical and genetic prognoses (for example, through evaluative testing of a stock by studying its progeny).


Brewbaker, G. L. Sel’skokhoziaistvennaia genetika. Moscow, 1966. (Translated from English.)
Lobashov, M. E. Genetika, 2nd ed. Leningrad, 1967.
Efroimson, V. P. Vvedenie v meditsinskuiu genetiku, 2nd. ed. Moscow, 1968.


References in periodicals archive ?
IS] are compatible with the low heterozygosity and low average number of alleles per locus observed in SSW.
A second factor that also accounts for expected heterozygosity and a third factor is the percentage of polymorphic loci present at the species level.
Kalgin Island exhibited the least diversity, as measured by allelic richness and heterozygosity, followed by Berners Bay and Yukon Flats (Table 1).
Loss of heterozygosity is a type of mutation that happens when one chromosome is lost, leaving you with only one working chromosome.
95 criterion), average number of alleles per locus (A), and average heterozygosity over all loci and subpopulations were calculated by hand using standard formulas (10).
Genotype summary data from 28 individuals (in both species) are given in Table 2; data for each microsatellite include number of alleles, size range of alleles detected, expected and observed heterozygosity, and probability of conformity to Hardy-Weinberg equilibrium expectations.
Mean observed heterozygosity tended to be lower than expected heterozygosity in 22 populations, suggesting that there is a deficiency of heterozygotes in those populations, as would be the case when there has been inbreeding.
Rogan and Knoll state that "Often many regions of the genome show amplification or loss of heterozygosity by aCGH.
These condominant markers will then be used to examine levels of heterozygosity as well as breeding and mating patterns in Epidendrum conopseum.
Blood samples from a captive flock of game-farm bred wild turkeys were subjected to random amplified polymorphic DNA (RAPD) analysis in order to ascertain the degree of general heterozygosity present.
Maynard, MA; 978-897-2800) announced the issuance of its fifth United States Patent 5,928,870, titled "Methods for the Detection of Loss of Heterozygosity.